OCW method , my first honest try . Come take a look and help .
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Metal God
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Thanks Andrew that was an interesting read .
My questions and or observations are not challenges but rather me just thinking out loud .
You'll need to read more of the paper to understand the quotes below
This makes me wonder how much of an effect rifle hold has on this because the barrel may be bedded in the stock but the stock is being held by a person and that person is sitting , standing or laying on something that is contacting the ground . How the rifle is being held must have an effect on the shock wave .
Think of it like this , when shooting a heavy recoiling rifle from a bench with front and rear bag. The felt recoil is huge to the shooter in comparison if the shooter was standing . Why ? because the shooter standing absorbs and disperses the shock wave through out his body while the shooter at the bench takes the full brunt right into his upper body .
After reading the whole paper . I see he gave great detailed graphs measurements and other detailed info on his "THEORY" . He then only said he ran the test with a strain gauge but did not give the same detailed info that actually confirms the "THEORY" I was expecting to see his Theory graphs side by side with the actual stain gauge graphs/data showing they were the same .
It was very interesting to read and seem to explain what many have known for decades . They just did not know the specifics as to why .
My questions and or observations are not challenges but rather me just thinking out loud .
You'll need to read more of the paper to understand the quotes below
This makes me wonder how much of an effect rifle hold has on this because the barrel may be bedded in the stock but the stock is being held by a person and that person is sitting , standing or laying on something that is contacting the ground . How the rifle is being held must have an effect on the shock wave .
Think of it like this , when shooting a heavy recoiling rifle from a bench with front and rear bag. The felt recoil is huge to the shooter in comparison if the shooter was standing . Why ? because the shooter standing absorbs and disperses the shock wave through out his body while the shooter at the bench takes the full brunt right into his upper body .
After reading the whole paper . I see he gave great detailed graphs measurements and other detailed info on his "THEORY" . He then only said he ran the test with a strain gauge but did not give the same detailed info that actually confirms the "THEORY" I was expecting to see his Theory graphs side by side with the actual stain gauge graphs/data showing they were the same .
It was very interesting to read and seem to explain what many have known for decades . They just did not know the specifics as to why .
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Andrew Leigh
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If the where the rifle barrel meet the receiver is not considered to be enough mechanical coupling then neither will your grip or the bedding.
The graphs are exactly that. The scale on the vertical axis is the measurement of the opening and closing of the muzzle. So when you operate QL this becomes real evident.
I have done numerous loads for friends using the OBT theory and we have managed to reach accurate loads within sometime as little a 6 rounds.
Tell you what, PM me an e-mail address. I will then send you a form to complete with the QL parameters and lets see what QL says about your loads.
The graphs are exactly that. The scale on the vertical axis is the measurement of the opening and closing of the muzzle. So when you operate QL this becomes real evident.
I have done numerous loads for friends using the OBT theory and we have managed to reach accurate loads within sometime as little a 6 rounds.
Tell you what, PM me an e-mail address. I will then send you a form to complete with the QL parameters and lets see what QL says about your loads.
Metal God asks me:
I’ve used the same lots of Federal, Hornady and Remington .308 Win match ammo in match conditioned M1 and M1A rifles with different twist and bore/groove dimensions that shot well under MOA through 600 yards. Same ammo in three different Win M70 based bolt guns with 3 different barrel lengths as well as bore/groove diameters that shot near ½ MOA through 600 yards properly tested. To say nothing about military teams using the same lot of ammo across a dozen or more rifles all tested well under 1 MOA through 600 yards with service rifles and magnum rounds testing under 1 MOA at 1000 in half a dozen different rifles; they win and set records with such stuff.
My questions:
When the shock wave goes back and forth in the barrel while the bullet goes through it and expands the bore .0001" at it's position, what happens to the high pressure gas behind the bullet? That wave will cross the bullet several times while it's in the barrel. Does that high pressure gas squirt around the bullet then go out of the barrel in front of it?
That shock wave has the same cycle time for a given barrel length regardless of the bullet's speed in the barrel or how the barrel's held. In a barrel with a tuner on it's front end, that tuner changes the whip frequency of its last several inches so bullets leave at the optimum point. Does that have to happen at the same time that shock wave is not at the muzzle?
Type? No. But the barrel has to wiggle and whip the same for each shot. If the barrel’s not free floated, receiver well fixed in its stock position (properly bedded) and the bolt face squared up with the chamber axis, it won’t flex the same from shot to shot and that masks the accuracy the ammo and barrel itself are capable of because of these unacceptable variables. Bullets have to be at least the diameter of the groove; smaller and accuracy is not all that good in any barrel.
I’ve used the same lots of Federal, Hornady and Remington .308 Win match ammo in match conditioned M1 and M1A rifles with different twist and bore/groove dimensions that shot well under MOA through 600 yards. Same ammo in three different Win M70 based bolt guns with 3 different barrel lengths as well as bore/groove diameters that shot near ½ MOA through 600 yards properly tested. To say nothing about military teams using the same lot of ammo across a dozen or more rifles all tested well under 1 MOA through 600 yards with service rifles and magnum rounds testing under 1 MOA at 1000 in half a dozen different rifles; they win and set records with such stuff.
Yes, but there’s four other things that have to be very good. Rifle mechanical fit and tolerances, ammo uniformity, test methodology that’s statistically significant and shooter marksmanship quality. Ever wonder why there’s thousands of “best accuracy” loads for a given cartridge?
My questions:
When the shock wave goes back and forth in the barrel while the bullet goes through it and expands the bore .0001" at it's position, what happens to the high pressure gas behind the bullet? That wave will cross the bullet several times while it's in the barrel. Does that high pressure gas squirt around the bullet then go out of the barrel in front of it?
That shock wave has the same cycle time for a given barrel length regardless of the bullet's speed in the barrel or how the barrel's held. In a barrel with a tuner on it's front end, that tuner changes the whip frequency of its last several inches so bullets leave at the optimum point. Does that have to happen at the same time that shock wave is not at the muzzle?
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Update
So I finally got out there to test the seating depths of the 43gr charge I had chosen as my OCW . There were very mixed results that I'm not sure what to make of . I started .040 off the lands and worked my way closer . The original test were .050 off the lands and .005 longer then the manuals 2.800 .
Here's a pic of two targets . These represent the first and last groups I shot or .040 off the lands (left) and .010 off the lands (right) NOTE : THESE WERE ALL 5 SHOT GROUPS AT 300 YARDS
I chose these two targets because as I got closer to the lands the tighter the groups got . As you can see the .030 difference in seating depth made a pretty big difference in group size . I was actually quite surprised there was that much of a noticeable difference . A 1.3 moa to a .66 moa is pretty big IMO .
OK that's great right ? It appears everything is going exactly as it is supposed to . " find the OCW then adjust seating depth to shrink your group is need be . Well yes buuuut my velocities were WAY out of wak . The worst group (left target) had an avg velocity of 2693fps with a ES-13 SD-5.9 . WOW that's great I was thinking , my first shots after a few foulers and this OCW thing is kicking butt . The target was 300yds away so I could not make out the group size through the spotting scope but knew I was on target .
So now I'll just post the Velocities of each group
OAL 2.815 - 2693fps , ES-13 SD-5.3 , 1.3 moa
OAL 2.825 - 2660fps , ES-104 SD-39 , 1.1 moa
OAL 2.835 - 2735fps , ES-97 SD-40 , .985 moa
OAL 2.845 - 2589fps , ES-165 SD-76 , .66 moa
What's up with that ?? As my velocities went to crap my groups shrank to well into the sub moa area . I have to say these were the worst ES/SD I've ever had .
At the range I knew those numbers were coming up but I had not measured the groups yet or really annualized any of the data so I had no idea the significance of those numbers . I like to wait until I get home so I can have all the data written out so to be easier to compare but I was expecting to see the opposite in terms of group size to velocity numbers .
Once I get home I start measuring and writing all the comparable data down . I like to right down each shots velocity but for what ever reason I did not right down the last groups individual velocities just the avg and the ES/SD .
So I'm looking at all this and I think maybe I had a huge internal case volume difference from case to case so I measured the H2O volume of each case from the first group (left target) and the third group ( target not shown ) but was just under moa .
Here's what those were
FIRST TARGET/GROUP with a ES-13 SD-5
2695fps - 55gr H20
2700fps - 54.8gr H2o
2689fps - 54.7gr H20
2687fps - 55.1gr H20
2692fps - 55.1gr H20
THIRD GROUP with ES-97 SD-40
2746fps - 55.2gr H20
2763fps - 55.3gr H20
2677fps - 56.3gr H20
2775fps - 55.8gr H20
2714fps - 55.1gr H20
I thought I was on to something when that third shot had the lowest velocity and a extra 1.0gr of H20 compared to the low avg but the very next case which was the highest velocity of the group also had about .5gr extra of H20 then the low avg . You think the highest velocity case might have a slightly lower volume then the avg low not higher .
And then you have that last group with an avg velocity 100+fps slower then the rest with an ES of 160 SD of 75 . anybody thinking chronograph problem ??? I'm not sure but I likely had the bullets flying over the top by only 2 or 3 inches . It was set , height wise the closest I may have ever had it . Not sure if that had an effect .
So interesting results for sure IMO . I'll be giving those at a COAL of 2.845 another try but this time I'll shot two 10 shot groups . Also , The fact The groups got better the closer the bullets was seated to the lands . I'll likely load a few at a COAL of 2.855 which should have the bullet just starting to press into the lands and see if that shrinks the group even more .
What do you all think of all that ??
Quick loads guys
168gr Hornady BTHP
Bullet length 1.233"
trim -2.005
OAL intended 2.815 and 2.845
Max OAL 2.855
Barrel length 23-13/16"
H20 see above measurements - Note OAL of 2.815 is the first set , 2.845 is the second set
So I finally got out there to test the seating depths of the 43gr charge I had chosen as my OCW . There were very mixed results that I'm not sure what to make of . I started .040 off the lands and worked my way closer . The original test were .050 off the lands and .005 longer then the manuals 2.800 .
Here's a pic of two targets . These represent the first and last groups I shot or .040 off the lands (left) and .010 off the lands (right) NOTE : THESE WERE ALL 5 SHOT GROUPS AT 300 YARDS
I chose these two targets because as I got closer to the lands the tighter the groups got . As you can see the .030 difference in seating depth made a pretty big difference in group size . I was actually quite surprised there was that much of a noticeable difference . A 1.3 moa to a .66 moa is pretty big IMO .
OK that's great right ? It appears everything is going exactly as it is supposed to . " find the OCW then adjust seating depth to shrink your group is need be . Well yes buuuut my velocities were WAY out of wak . The worst group (left target) had an avg velocity of 2693fps with a ES-13 SD-5.9 . WOW that's great I was thinking , my first shots after a few foulers and this OCW thing is kicking butt . The target was 300yds away so I could not make out the group size through the spotting scope but knew I was on target .
So now I'll just post the Velocities of each group
OAL 2.815 - 2693fps , ES-13 SD-5.3 , 1.3 moa
OAL 2.825 - 2660fps , ES-104 SD-39 , 1.1 moa
OAL 2.835 - 2735fps , ES-97 SD-40 , .985 moa
OAL 2.845 - 2589fps , ES-165 SD-76 , .66 moa
What's up with that ?? As my velocities went to crap my groups shrank to well into the sub moa area . I have to say these were the worst ES/SD I've ever had .
At the range I knew those numbers were coming up but I had not measured the groups yet or really annualized any of the data so I had no idea the significance of those numbers . I like to wait until I get home so I can have all the data written out so to be easier to compare but I was expecting to see the opposite in terms of group size to velocity numbers .
Once I get home I start measuring and writing all the comparable data down . I like to right down each shots velocity but for what ever reason I did not right down the last groups individual velocities just the avg and the ES/SD .
So I'm looking at all this and I think maybe I had a huge internal case volume difference from case to case so I measured the H2O volume of each case from the first group (left target) and the third group ( target not shown ) but was just under moa .
Here's what those were
FIRST TARGET/GROUP with a ES-13 SD-5
2695fps - 55gr H20
2700fps - 54.8gr H2o
2689fps - 54.7gr H20
2687fps - 55.1gr H20
2692fps - 55.1gr H20
THIRD GROUP with ES-97 SD-40
2746fps - 55.2gr H20
2763fps - 55.3gr H20
2677fps - 56.3gr H20
2775fps - 55.8gr H20
2714fps - 55.1gr H20
I thought I was on to something when that third shot had the lowest velocity and a extra 1.0gr of H20 compared to the low avg but the very next case which was the highest velocity of the group also had about .5gr extra of H20 then the low avg . You think the highest velocity case might have a slightly lower volume then the avg low not higher .
And then you have that last group with an avg velocity 100+fps slower then the rest with an ES of 160 SD of 75 . anybody thinking chronograph problem ??? I'm not sure but I likely had the bullets flying over the top by only 2 or 3 inches . It was set , height wise the closest I may have ever had it . Not sure if that had an effect .
So interesting results for sure IMO . I'll be giving those at a COAL of 2.845 another try but this time I'll shot two 10 shot groups . Also , The fact The groups got better the closer the bullets was seated to the lands . I'll likely load a few at a COAL of 2.855 which should have the bullet just starting to press into the lands and see if that shrinks the group even more .
What do you all think of all that ??
Quick loads guys
168gr Hornady BTHP
Bullet length 1.233"
trim -2.005
OAL intended 2.815 and 2.845
Max OAL 2.855
Barrel length 23-13/16"
H20 see above measurements - Note OAL of 2.815 is the first set , 2.845 is the second set
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Knowing the most accurate rifles have a 4X to 5X extreme spread across many 5-shot groups at 300 yards, I don't consider any of them to represent the real accuracy any load produces.
That said, if several charge weights produce single groups about the same size (within 10 to 20 percent), there's a good chance the rifle shoots those loads half that of what the group measures. Us humans' variables add to those of the ammo; especially with hand held rifles resting atop bags on a bench top. I cannot shoot very accurate with a rifle held against my shoulder as it rests on bags atop a bench I'm sitting at. A Nat'l Champion suggested I test ammo slung up in prone with a bag under the stock fore end and heel. Testing that way, my groups were half to a quarter the size of those shot with a hand held rifle atop a bench. Benchresters know their rifles shoot most accurate in free recoil untouched by them except for a finger on the 2-ounce trigger. If they shoulder them, they shoot much larger groups.
The left group shows a lot of horizontal shot stringing. And I note you're using LC-12-LR cases. Did you get those cases in a once fired state (surplus)? If so, there's a good chance they were fired in a military firearm whose bolt face isn't square with the chamber axis. Their case head's are out of square with their long axis. That causes horizontal shot stringing in 2-lug bolt guns whose lugs are at 12 and 6 o'clock when in battery. Tests show it causes 1/2 to 2/3 MOA horizontal stringing.
That said, if several charge weights produce single groups about the same size (within 10 to 20 percent), there's a good chance the rifle shoots those loads half that of what the group measures. Us humans' variables add to those of the ammo; especially with hand held rifles resting atop bags on a bench top. I cannot shoot very accurate with a rifle held against my shoulder as it rests on bags atop a bench I'm sitting at. A Nat'l Champion suggested I test ammo slung up in prone with a bag under the stock fore end and heel. Testing that way, my groups were half to a quarter the size of those shot with a hand held rifle atop a bench. Benchresters know their rifles shoot most accurate in free recoil untouched by them except for a finger on the 2-ounce trigger. If they shoulder them, they shoot much larger groups.
The left group shows a lot of horizontal shot stringing. And I note you're using LC-12-LR cases. Did you get those cases in a once fired state (surplus)? If so, there's a good chance they were fired in a military firearm whose bolt face isn't square with the chamber axis. Their case head's are out of square with their long axis. That causes horizontal shot stringing in 2-lug bolt guns whose lugs are at 12 and 6 o'clock when in battery. Tests show it causes 1/2 to 2/3 MOA horizontal stringing.
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Metal God
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BartB said:
I think on the whole I agree but what about the groups getting consistently smaller as the seating depth changed . Does that represent anything in the test ? I'd think If there were no true representation through out the groups . I would not have got a consistent shrinking of the group sizes as I consistently increased COAL ??
I'm going to breakfast right now but when I get back I'll post all the targets so to compare . Should be an hour-ish
Metal God,
Run that same test again. If the results are within 10% of what that first one shows, then odds are the test is valid. You need more than one 5-shot group per load specs to validate it. If you do that complete test 3 times with almost the same results, then it's getting closer to really showing you what each load spec does.
Run that same test again. If the results are within 10% of what that first one shows, then odds are the test is valid. You need more than one 5-shot group per load specs to validate it. If you do that complete test 3 times with almost the same results, then it's getting closer to really showing you what each load spec does.
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Metal God
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Here's all four targets in order top left to bottom right COAL , 2.815 , 2.825 , 2.835 , 2.845 . The bottom right target has a significant POI shift from the others . How ever I'm not 100% sure that's not do to a scope adjustment . I also ran a ladder test the same day that needed a slight scope adjustment to the right . That could explain the shift but I don't remember if that's the case for sure .
All four still too close to the same size for me.
Shoot 3 or 4 groups atop each other on the same target for each COAL then see what happens,
5-shot groups don't impress me. 5 or more atop each other using the same aiming point says a lot.
Shoot 3 or 4 groups atop each other on the same target for each COAL then see what happens,
5-shot groups don't impress me. 5 or more atop each other using the same aiming point says a lot.
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That's a good idea using the same targets or over laying them but I don't have the turret adjustments written down so I don't think that will help . I did just confirm I'll be shooting again with a buddy later this week . I'll load that same test as well as a extra set of loads with the bullet touching the lands .
If they come out pretty much the same I'll likely consider that confirmation . It's unlikely I'll do it a third time If the results are the same the second time around .
I'll also try to narrow down the ladder test I did .
If they come out pretty much the same I'll likely consider that confirmation . It's unlikely I'll do it a third time If the results are the same the second time around .
I'll also try to narrow down the ladder test I did .
Andrew Leigh
Member
Hi,
Barrel time on Load 1 COL 2.815" 55.0gr H2O average
OBT Node 1.093 - Actual 1.185 - OBT Node 1.219
Barrel time on Load 2 COL 2.845" 55.5gr H2O average
OBT Node 1.093 - Actual 1.202 - OBT Node 1.219
I have modelled your two loads in QL. QL confirms your targets in that your second group is the better of the two and that this is the group closest to the node for your barrel. Moving closer to the lands has increased the pressure due to the additional inertia required to overcome the lands when this close. This is evidenced in the increase in velocity.
This is a model of a .308 Win with 165gr. Hornady's. You can see that the effect of intertia picks up from 1.0mm (0.040") from the lands.
The bullet I have used is part number #30501 please confirm if this is correct.
So if you use the SAME components for each respective load and COL, and you wish to be at 1.219ms OBT then;
COL 2.815" the charge weight should be 42.1gr.
COL 2.845" the charge weight should be 42.5gr.
And this should achieve the same result.
A final note, two sets of shots within a grouping is more often than not indicative of the barrelled action moving in the stock. If you are bedded then please make sure that your action screws are suitable tight.
Barrel time on Load 1 COL 2.815" 55.0gr H2O average
OBT Node 1.093 - Actual 1.185 - OBT Node 1.219
Barrel time on Load 2 COL 2.845" 55.5gr H2O average
OBT Node 1.093 - Actual 1.202 - OBT Node 1.219
I have modelled your two loads in QL. QL confirms your targets in that your second group is the better of the two and that this is the group closest to the node for your barrel. Moving closer to the lands has increased the pressure due to the additional inertia required to overcome the lands when this close. This is evidenced in the increase in velocity.
This is a model of a .308 Win with 165gr. Hornady's. You can see that the effect of intertia picks up from 1.0mm (0.040") from the lands.
The bullet I have used is part number #30501 please confirm if this is correct.
So if you use the SAME components for each respective load and COL, and you wish to be at 1.219ms OBT then;
COL 2.815" the charge weight should be 42.1gr.
COL 2.845" the charge weight should be 42.5gr.
And this should achieve the same result.
A final note, two sets of shots within a grouping is more often than not indicative of the barrelled action moving in the stock. If you are bedded then please make sure that your action screws are suitable tight.
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Metal God
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Double groups in the same sting ??
WAIT what , how could this be . I can't believe that's even possible 
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OK fine it's VERY possible 
I had these same problem and it turned out to be loose action screws . Those groups were shot maybe 2k rounds ago now with the same rifle I'm running the test with .I have not had double groups in all that time . I did think the same thing when looking at the second group . It sure looks like two separate groups but I've not checked the action screws yet . If they came loose ,that would SUCK so bad because I'd have to throw this whole test out . Reason IMO is that I have no idea if they came loose when that was . Maybe I'll go check that now Do you mean 2.815 is 42.5 and 2.845 is 42.1 . The other way as you posted it should put MUCH more pressure on the 2.845 load then the other because of the bullet is closer to the lands ????
Will you run those numbers again but this time with the bullet right at the land . So a COAL of 2.855 and that should be just starting to press into the lands . ( it's NOT a full jam )
Bullet number #305016
EDIT : Just checked the action screws . They're GTG nice and tight .
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Andrew Leigh
Member
Remember that the case capacity has increased due to seating further out and that the average capacity on the 2.845" was 0.5gr H2O more. I did double check as I had the same initial concern as you did. Then on the 2.815" load is have the converse 0.5gr H2O less and you seated further in. In effect a double whammy and we have not taken into account the effect on pressure through engaging the rifling.
Not easy due to the exponential pressure curve, I would have to take and educated guess using the QL Shot Start Initialisation Pressure (SSIP) of 7 200psi. The SSIP I used for your 2.845" load was 4 550psi (this I arrived at by keeping the powder burn rate the same and modifying the SSIP to get your recorded velocities.
So using the components from the 2.845" load (i.e. larger internal volume) if you are kissing the lands load to 41.0gr. Never underestimate the effect of inertia when engaging the lands.
Cheers
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Update
well I finally got back out to do my final testing of the Dan Neberry OCW method . If you have followed this thread you know I was trying to keep my test as true as I could to the original method .
I have this thread going on a couple different forums so I'm not completely sure who has said what where so I'll just post my conclusions here as I see them .
First as I stated when I started this thread . I did not have much faith in this method . Upon running these test I have concluded that I was indeed WRONG . this method (to this point) has been one of the best ways to find a load I've used . I'll admit I have some final confirming but believe my test have shown that The OCW test per Dan's instructions worked quite well .
summary
Savage 308 model 10
168gr Hornady BTHP
IMR-4895
LC-12-LR cases , sized .002 short of fired cases using bushing die "NO" expander
Fed match primers
First test was the 3 shot groups in charge weight increments of .4gr to find a common set of charges that had the least amount of vertical stringing from the triangulated center of each 3 shot group .
First targets shot at 200yds
It's been documented in earlier post what the triangular centers were and why I chose 43gr as my OCW . I got other suggestios as to what charge to use and there were a couple . I only really considered one and that was 42gr . More on the 42gr charge later
After deciding on 43gr as my OCW I went ahead and loaded 4 different 5 shot lots of 43gr with different seating depths .
43gr seating depth test at 300 yards
As you can see as the seating depth changed ( seated longer each test ) the groups got consistently smaller . At that point I was starting to be encouraged about this method .
So it took awhile but I finally got out to confirm the seating depth choices were in fact valid . Long story short . I'll either be going with 43gr at 2.845 or 2.855 . They both shot equally well but the 2.855 did not have as good a ES/SD
3rd test at 300yards 43gr at 2.855 COAL The black is a 2.6" circle
That's very close to 1/2 moa out to 300yds which would likely be one little tiny hole at 100yds . So IMHO this method works quite well . I shot two 5 shot groups at that seating depth and they both shot the same . The only issue was my velocities . Through out the day regardless as to the charge the 2.855 COAL shot the best but also had the worst ES/SD .
As I said above I also shot 2 groups of the 42gr charge . Although it did OK right at 1 moa at 300yds . It did not do as well as the 43gr charge .
Also , I'm not sure if I mentioned it here but I also was running a ladder test using some of the same components .
Ladder test
168gr Hornady BTHP
IMR-4895
LC-14 cases , sized to GO-GAGE length using bushing die "WITH" expander
Win standard LR primers .
I had already run the first part of the ladder test firing one shot of each charge moving up in increments of .4gr the last time I was out .42.2gr was the highest I could go with these components with out pressure signs . I came up with 40.6gr , 41.0gr , 41.4gr as having the least amount of vertical stringing at 300 yards . I chose 41gr as the charge I'd try . I then tried 41gr at multiple seating depths at 300 yards
Ladder test seating depth target
As you can see once again as the seating depth grew the groups shrank-ish . I how ever agian had VERY bad ES/SD at the seating depth of 2.855 even though it's a very good group of .6 moa at 300 yards
My conclusion is at this point is that both the OCW and Ladder test methods work good . I am how ever slightly confused as to why my COAL of 2.855 continued to show erratic velocities regardless as to which method or charge I used while still grouping the best .
Any thoughts ?
well I finally got back out to do my final testing of the Dan Neberry OCW method . If you have followed this thread you know I was trying to keep my test as true as I could to the original method .
I have this thread going on a couple different forums so I'm not completely sure who has said what where so I'll just post my conclusions here as I see them .
First as I stated when I started this thread . I did not have much faith in this method . Upon running these test I have concluded that I was indeed WRONG . this method (to this point) has been one of the best ways to find a load I've used . I'll admit I have some final confirming but believe my test have shown that The OCW test per Dan's instructions worked quite well .
summary
Savage 308 model 10
168gr Hornady BTHP
IMR-4895
LC-12-LR cases , sized .002 short of fired cases using bushing die "NO" expander
Fed match primers
First test was the 3 shot groups in charge weight increments of .4gr to find a common set of charges that had the least amount of vertical stringing from the triangulated center of each 3 shot group .
First targets shot at 200yds
It's been documented in earlier post what the triangular centers were and why I chose 43gr as my OCW . I got other suggestios as to what charge to use and there were a couple . I only really considered one and that was 42gr . More on the 42gr charge later
After deciding on 43gr as my OCW I went ahead and loaded 4 different 5 shot lots of 43gr with different seating depths .
43gr seating depth test at 300 yards
As you can see as the seating depth changed ( seated longer each test ) the groups got consistently smaller . At that point I was starting to be encouraged about this method .
So it took awhile but I finally got out to confirm the seating depth choices were in fact valid . Long story short . I'll either be going with 43gr at 2.845 or 2.855 . They both shot equally well but the 2.855 did not have as good a ES/SD
3rd test at 300yards 43gr at 2.855 COAL The black is a 2.6" circle
That's very close to 1/2 moa out to 300yds which would likely be one little tiny hole at 100yds . So IMHO this method works quite well . I shot two 5 shot groups at that seating depth and they both shot the same . The only issue was my velocities . Through out the day regardless as to the charge the 2.855 COAL shot the best but also had the worst ES/SD .
As I said above I also shot 2 groups of the 42gr charge . Although it did OK right at 1 moa at 300yds . It did not do as well as the 43gr charge .
Also , I'm not sure if I mentioned it here but I also was running a ladder test using some of the same components .
Ladder test
168gr Hornady BTHP
IMR-4895
LC-14 cases , sized to GO-GAGE length using bushing die "WITH" expander
Win standard LR primers .
I had already run the first part of the ladder test firing one shot of each charge moving up in increments of .4gr the last time I was out .42.2gr was the highest I could go with these components with out pressure signs . I came up with 40.6gr , 41.0gr , 41.4gr as having the least amount of vertical stringing at 300 yards . I chose 41gr as the charge I'd try . I then tried 41gr at multiple seating depths at 300 yards
Ladder test seating depth target
As you can see once again as the seating depth grew the groups shrank-ish . I how ever agian had VERY bad ES/SD at the seating depth of 2.855 even though it's a very good group of .6 moa at 300 yards
My conclusion is at this point is that both the OCW and Ladder test methods work good . I am how ever slightly confused as to why my COAL of 2.855 continued to show erratic velocities regardless as to which method or charge I used while still grouping the best .
Any thoughts ?
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The only question I would have is why you are doing the OCW test at 200 yards, when Dan Newberry specifies that the testing should be done at 100 yards to eliminate any issues with wind drift, etc. 100 yards is the preferred distance for this test.
Also, you should not be looking for vertical stringing, but rather you should be looking for POI. Loads that cluster around the same POI are where you want to begin by choosing a load in the middle of groups that are at the same POI. Then you can experiment with charge weights and bullet seating depth.
The point behind the OCW test is to find a load that will be most resistant to increases and decreases in pressure...i.e. weather conditions. For example, working up a load during the summer, then using that load in the winter to hunt deer.
Hope this helps...
Also, you should not be looking for vertical stringing, but rather you should be looking for POI. Loads that cluster around the same POI are where you want to begin by choosing a load in the middle of groups that are at the same POI. Then you can experiment with charge weights and bullet seating depth.
The point behind the OCW test is to find a load that will be most resistant to increases and decreases in pressure...i.e. weather conditions. For example, working up a load during the summer, then using that load in the winter to hunt deer.
Hope this helps...
OP
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Your questions have been answered in detail in this thread .
I chose 200yds to clearly define the 3 shot groups . I felt I can shoot well enough and that at 100yds I my have some groups that were just one hole . 200 yds seemed like a good choice and was sure to shoot in morning with little to no wind .
In my first post it shows the measurements as to where each 3 shot POI in relation to POA . 42.6 , 43 , 43.4 all were with in .22" vertically and .47" horizontally at 200yds so that would have been .11" vert and .23" horiz at 100 yds . I'd think those would have been hard to see a difference at 100yds seeing how my holes are .308 in size . Either way the three charges were by far the most consistent per Dan's instructions and is why I choose the the middle charge of 43gr
By choosing the 43.0gr charge I believe I did just that . Unlike many that said I should now start testing in .2gr increments to narrow down the charge . Dan does not mention anywhere to do that . . If you are seing changes in your POI , group sizes with .2gr increments . I believe you have not found your OCW . My results should give me a .8gr swing of pressures that will not effect POI which is the point of the OCW method . I believe all this has been discussed in great detail in this thread . I know when I see 4 pages in a thread I sometimes skip to the end . In this case there has been a lot discussed and why each poster felt the way they do .
Do you feel you see another charge/charges that should have been my OCW ?
I chose 200yds to clearly define the 3 shot groups . I felt I can shoot well enough and that at 100yds I my have some groups that were just one hole . 200 yds seemed like a good choice and was sure to shoot in morning with little to no wind .
In my first post it shows the measurements as to where each 3 shot POI in relation to POA . 42.6 , 43 , 43.4 all were with in .22" vertically and .47" horizontally at 200yds so that would have been .11" vert and .23" horiz at 100 yds . I'd think those would have been hard to see a difference at 100yds seeing how my holes are .308 in size . Either way the three charges were by far the most consistent per Dan's instructions and is why I choose the the middle charge of 43gr
By choosing the 43.0gr charge I believe I did just that . Unlike many that said I should now start testing in .2gr increments to narrow down the charge . Dan does not mention anywhere to do that . . If you are seing changes in your POI , group sizes with .2gr increments . I believe you have not found your OCW . My results should give me a .8gr swing of pressures that will not effect POI which is the point of the OCW method . I believe all this has been discussed in great detail in this thread . I know when I see 4 pages in a thread I sometimes skip to the end . In this case there has been a lot discussed and why each poster felt the way they do .
Do you feel you see another charge/charges that should have been my OCW ?
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jwrowland77
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I'm going on Monday to test the charge weight swing claims of the OCW method . I went a head and loaded up 20 rounds but instead of weighing each charge I just threw them from my Hornady powder measure . While setting up for the throw I was seeing .6gr swing in charges . The target weight was 43gr and I was getting 42.7 through 43.3 . This should be interesting . I also change one thing on the load .
I was getting those inconsistent velocities at 2.855 so I went ahead and seated these to 2.850 . I was getting good groups with 2.845 but better with 2.855 , thought I'd split the difference and see if I could stabilize the velocities .
me said:
I was getting those inconsistent velocities at 2.855 so I went ahead and seated these to 2.850 . I was getting good groups with 2.845 but better with 2.855 , thought I'd split the difference and see if I could stabilize the velocities .
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