WHY is my first shot high?

[docsleepy]

OK. In the quest of reducing velocity dispersion. (I'll get to the OCW effort a bit later)

No way to get "new" cases, so for Group 1, I gathered 5 "once fired" .308's Remington that I had on hand for another gun. FL size, trim, bevel, neck size, prime, 41.2 gr Varget from Chargemaster, seat bullet. Note I generally always neck down .308's for 7mm08 so I end up with a tighter fit in the neck region in my sporter barrel.

Group 2: 5 previously fired cases: necksize, no trim, prime, 41.2 gr Varget from Chargemaster, seat bullet (these felt much less neck tension)

Group 3: 5 previously fired cases: FL size, prime, trim, bevel, no neck size, 41.2 gr Varget from Chargemaster, seat bullet.

Gave up on heading 29 miles to the range this late (spent most of day working on an engine), may be able to anneal some cases tonight, create another test group, head to range tomorrow. If I do, I will run them into the FL sizer only ONCE.


Discoveries so far:
1. My Lee bullet seater was seating much less precisely than I had remembered. These are light-for-caliber 120 grain Sierra spire points. The cases group in group three (tighter neck tension) tended to have too-long COAL by .005 or more ; the cases from group two (much looser neck by my "feel" of the press) tended to have too-short COAL (by roughly .004) ....this was unexpected. And, since I'm near "lands" -- this might be very significant. [In 6PPC, my Lee did just about as good as a Wilson! so this is a useful discovery for me. Perhaps I need a better or custom seater......] I readjusted the worst outliers....by COAL.

2. I have a simple Hornady comparator set, may check that on them, if so, perhaps adjust for similar comparator readings?

3. Note that I switched to the Chargemaster to avoid issues of powder variabilities.

 

[BullfrogKen]

What do you mean, "No way to get "new" cases"?

Midway has some available right now -


http://www.midwayusa.com/product/1311133737/norma-reloading-brass-7mm-08-remington


That stuff is still factory produced. Buy some and I'll be shocked if using it doesn't reduce that huge velocity spread.

 

[docsleepy]

What do you mean, "No way to get "new" cases"?

Midway has some available right now -

http://www.midwayusa.com/product/1311133737/norma-reloading-brass-7mm-08-remington

That stuff is still factory produced. Buy some and I'll be shocked if using it doesn't reduce that huge velocity spread.

BullfrogKen:
Yes, I saw that, this afternoon, put it in my "cart" even, and then took it back out. [You are right, 7mm08 is available (at $1/case) ; I should have said that what I PREFER isn't...]
I prefer Hornady match 308 to neck down, and besides, I simply can't be dependent on "new" brass for every shot!! (Lapua .308 is also available....at a price) I worked with 50 ppc cases for months and months; I've read that many competitors use the same brass for the entire life of one competition barrel; hopefully this can be done with this rifle also with some form of reloading....
....I don't have money to burn and I settled on getting some more bullets for 7mm and 6.8SPC, until I have the results of this current test to see if indeed less-worn brass is better....

I still don't get why these are "huge velocity spreads" when they are similar to some "match" ammunition that I cited in the article published online?

If indeed I am "overworking" the brass, then wouldn't annealing the neck and simply full-length sizing it once be adequate to address your concerns?

And besides, does this have ANYTHING to do with the "first shot" problem? How would it be that my brass knew which one was destined to be FIRST to be shot, during reloading? I think it would be great if I could improve my process, but the major improvement (to date) has been to grease-patch that barrel.

Why don't you give us a rundown on how YOU handload and perhaps I might learn something? That would probably be VERY helpful!

 

[Andrew Leigh]

It may or may not have something to do the the first shot flying but first we need to get the velocity spread down. This is a variable that we know that is higher than it should be and must therefore be taken out of the equation before proceding. There is a direct correlation between velocity spread and accuracy, in my loading experince that is. I like mine below +-15fps and get real warm and fuzzy when they are below +-10fps.

 

[murf]

so, how does factory ammo work in that gun?

shoot a five shot group of that factory ammo over a chrony. easier to discuss your quest if you have a baseline for comparison.

murf

 

[BluegrassDan]

I think you're over complicating this. There should be no need to overwork the brass so much. I don't spend nearly that much time on brass prep and my Kimber groups sub-MOA.

The grease thing should not be necessary.

Inconsistant velocities could be a culprit. I still think you need to check the torque with a real torque wrench.

 

[docsleepy]

BluegrassDan -- I just had to chuckle reading your post! Yep, I think we are over complicating it....but then again, if **I** had a KIMBER, then I probably wouldnt be having the problem!!!


I think everyone is going to be much happier with the velocity data that I collected today.

Today was a completely overcast day here. I am just not an expert at getting my chrony to work, except on overcast days: it worked perfectly today. Where I shoot is bordered by trees and hills, and on sunny days (like the day I collected the past data that drove everyone crazy), it is just really difficult to get that chronograph to work well. A diffuser helps, but still some shots it just won't register. I have to wonder about its accuracy on those days.

ANYWAY: I made up different batches of rounds as above; the 4th group was my usual technique, but only ONE FL resize. The usual technique is: Deprime, Anneal neck, dry, lube, FL resize (1 or 3), trim, bevel, smooth, necksize/prime, Lee powder thrower, bullet seat, wipe off lube.

Each group differs in some way, as noted below.

 

[docsleepy]

The first set to be shot was Group 4: my much-used Hornady brass, annealed, FL sized (only once this time), trim, bevel, smooth, necksize, Chargemaster 41.2 grains Varget, seat 120gr Sierra SP, trying to keep Hornady .28 comparator measurement between 2.272-2.276. This took some doing.

Average velocity is 2881, SD is 27.1 The first shot is a bit high, and I dunno exactly what is happening with that last shot.

Prior to doing all this, I re-measured the COAL to the lands, Hornady device. Couldn't find my test shell, had to make another one....took a while. Lands are at a comparator length of 2.273. COAL of 2.769-2.772.

Loaded round neck dia is .312. From a fired shell necked up and down until it would JUST BARELY go into the throat, my rifle's throat is just over .316, meaning I have .002 on each side.

 

[docsleepy]

The second group shot is Group 1 -- "once fired" RP brass .308, "new" to me, not annealed, FL sized x 1, necksized x 1, chargemaster 41.2 grains, bullet seated to similar specs as above.

Average 2898, SD 10.1 ( much better). Note the zero is moving.

 

[docsleepy]

The third group shot is supposed to be old cases, annealed, FL size, skip the neck size (Group 3). Unfortunately, the first shot (#11) I picked up a case that belonged to Group 2 (neck size only).

For the shots #12-#16 in Group 3 (skip the neck size) the average velocity is 2918, SD 8.43.

Also note, that prior to this group, I noticed that the chrony had been turned approximately 5 degrees (which would give slightly erroneously low velocities) and I fixed that prior to this group.

I shot a total of 20 shots over about 45 minutes, and the barrel gained some warmth. The zero is now lower and leftward of where it started.

 

[docsleepy]

The final group is old cases, annealed and neck sized only. Shot #11 in the previous photo should belong to this group, so I have pencilled in where it would have been on this photo. The average velocity is 2901, and the SD is 6.6 fps.

These cases have obviously lower neck tension when you seat the bullet. The zero is lower.

One of the rounds is pretty short -- comparator 2.263, and it groups lower than the others.


I'm sure you figured this out by now, but each shot is numbered, and the comparator length (Hornady .28 comparator, zeroed with the comparator between the jaws) is listed first, and the velocity is listed second.


OK guys, what do we learn from these? Despite the grease, that first shot (#1 in previous photo) is still a tiny bit high....although much much better than the 2-3" I had been seeing when I first started this thread.

 

[docsleepy]

Murf: Don't actually know how store bought works in this gun. Haven't ever bought any, since they often want $30+ for twenty rounds. With the good velocity data achieved today maybe ill be ok with just my handloads


Andrew Leigh sent me very helpful stuff to do an ocw analysis. My next chance for that wont come until the weekend or later. But good idea. I still don't have a FAT so all I can say is those screws were TIGHT.

 

[Andrew Leigh]

Great stuff Doc,

I feel that you have made real progress here. Those last std d's are looking awesome. Methinks that neck tension was a major culprit which you now have a better handle on.

I think that when you are through with the OCW that you will be able to see if indeed you load was on an "accuracy node" which I don't think it is. Please fire 3 fouling shots before starting with the OCW. From a load development perspective let's not allow the first one or two flyers to influence that. Let's first make sure the load is correct and then sort out the flyer.

I think you mentioned elsewhere in the thread that you were able to do sub MOA groups on other rifles. If it were not for that fact I would mention breathing control. I have e-mailed you another document to read, go down an have a look at figure 8, you may have a deja vu moment. Or as my friend say a deja moo moment ...... where have I seen this BS before .

 

[docsleepy]

OK, I'm going to attempt the OCW process [strongly urged by Andrew Leigh] tomorrow, weather permitting.

It should be sunny, and that probably means my chrony will give screwy results.

I will shorten the COAL by .010 to back off the lands a tiny bit, and attempt to use exactly the same reload techniques and quality that I used in the most recent efforts. I'll attempt about 6 or so 3-shot groups differing by 0.4 grains, using a Chargemaster to create the loadings. Three foulers at the beginning, grease patches at the beginning.

Weather is supposed to be cold here, in the high 50's. I'll attempt to let the gun cool fairly well between groups.

 

[Andrew Leigh]

Hey Doc,

wish you well with your loads. Just a thought, the three foulers will take care of the shooting high syndrome so I would not use the grease for now. I still think it is treating the symptom and not the cause. I do not know of anyone who uses such a practice when developing loads.

Do you have a beam scale and powder trickler? Personally my chargemaster is not accurate enough. If you have the beam scale I think for this exercise that you will get better results.

Don't forget to the order in which to shoot. Load 1, Shot 1, Target 1 and then Load 2, Shot 1, Target 2 thaen Load 3, Shot 1, Target 3 etc. This is important 'cause as you barrel warms slowly the POI shifts, at least this way it shifts the same for the three different sequences of shots so you should get great repeatability. The POI is not crucial, the group size and pattern is.

Good luck, can't wait for the results.

 

[docsleepy]

Well, too late, all the charges are already made on the charge master. Find has the original algorithm and works reasonably well.

I'll skip the grease if you think that best. I understood the round robin technique

 

[Andrew Leigh]

Yip skip the grease for now.

 

[docsleepy]

Results of Optimal Charge Weight Tests

Here are the results of the OCW tests:

Temp in the 60's and 70's, hence able to go up to 42.2 grains Varget, 120 grain Sierra SP. Seated approx .010 deeper, thus approx .010 off the lands, Hornady comparator roughly +/- .002 variation. 0.4 grain steps. I did run a modest number of lightly greased patches, and then shot 3 foulers -- but the 2nd and 3rd were not on the same line, so I shot one or two more until it seemed really consistent. It was a bright sunny day, and I had several sheets of paper attempting to create a diffuser for the chrony....which promptly caused the rods and diffuser-paper to fall over....so I gave up on the chrony.

I had two more Hornady Match Brass show signs of separation, so I had to use some RP brass (same brass that were used in the last test above). Shots fired with this brass are outlined in blue sharpie.

My educated estimation of the geometric center of each group is marked with a red circle. The third photo shows where the centers moved with each set of powder.

The shots were done "round robin" (as per the OCW instructions), NOT all three at one powder level at a time. 16X scope, 100 yards, 7mm08 caliber.

 

[docsleepy]

Here is the compiled set of "estimated geometric centers"

So which is the best powder charge to use??? What do I do with the anomalous results (strangely low) at 41.6 grains??

 

[docsleepy]

Midway today has Hornady .308 match cases available.....restocking my supply!

 

[Andrew Leigh]

I am unable to view the first target larger when clicking on it. The second one is fine as is the one in the next post. Could you upload the first one again please?

 

[Andrew Leigh]

Ok Doc,

Firstly nice shooting. My initial observation would be that your last load at 42.4 is approaching the accuracy node.

The way you have triangulated it correct but unfortunately it would appear as if you have not yet reached the accuracy node which I believe is closer to the 42.4gr. You should have been around the 2900fps mark?

Unless you had signs of pressure you may have stopped the process a little short in terms of the load. That is why I load over by two or three load increments, these may not be fired if there are signs of pressures or if the velocities exceed allowable limits.

If it was me, and had I not observed no signs of pressure, I would load 5 each of 42.0 / 42.4 / 42.8 / 43.2 and throw those down the range after the mandatory three fouling rounds. 5 because you can then compare them to where you were as you were able to pop three into one hole with your previous load lets see if the other two don't fly. Have you a beam scale to throw these charges with? I think that you may well settle on 42.4 or 42.8. The 120gr. Sierra SPT has a maximum vargret load of 43.8gr (according the the Sierra Infinity Software) so you should be OK.

On the fouling rounds may I suggest that you load them at 42.4gr. and shoot them on a target to see if, with the once formed brass and the slightly larger load, wheather the first round still prints as high. That way you can kill two birds with one stone.

That last two groups are great, looks like .75 and 0.50" respectively, these in my opinion are approaching or at the accuracy node, we need one or two groups on the other side to see if they get better or open up again. The final two loads POI print almost on top of each other which is great.

Generally it would appear as if the brass has made a difference, do you concur?

Did you happen to measure velocities or not, it would appear as if your std devaitions have improved.

How are you feeling about the latest round, do you feel like you are getting anywhere or just going around and around? The 5 shots groups will be telling.

Cheers

 

[docsleepy]

Here is the first set of groups (lowest powder charges) uploaded again:

 

[docsleepy]

Ok Doc,

Firstly nice shooting. My initial observation would be that your last load at 42.4 is approaching the accuracy node.

The way you have triangulated it correct but unfortunately it would appear as if you have not yet reached the accuracy node which I believe is closer to the 42.4gr. You should have been around the 2900fps mark?

Unless you had signs of pressure you may have stopped the process a little short in terms of the load. That is why I load over by two or three load increments, these may not be fired if there are signs of pressures or if the velocities exceed allowable limits.

If it was me, and had I not observed no signs of pressure, I would load 5 each of 42.0 / 42.4 / 42.8 / 43.2 and throw those down the range after the mandatory three fouling rounds. 5 because you can then compare them to where you were as you were able to pop three into one hole with your previous load lets see if the other two don't fly. Have you a beam scale to throw these charges with? I think that you may well settle on 42.4 or 42.8. The 120gr. Sierra SPT has a maximum vargret load of 43.8gr (according the the Sierra Infinity Software) so you should be OK.

On the fouling rounds may I suggest that you load them at 42.4gr. and shoot them on a target to see if, with the once formed brass and the slightly larger load, wheather the first round still prints as high. That way you can kill two birds with one stone.

That last two groups are great, looks like .75 and 0.50" respectively, these in my opinion are approaching or at the accuracy node, we need one or two groups on the other side to see if they get better or open up again. The final two loads POI print almost on top of each other which is great.

Generally it would appear as if the brass has made a difference, do you concur?

Did you happen to measure velocities or not, it would appear as if your std devaitions have improved.

How are you feeling about the latest round, do you feel like you are getting anywhere or just going around and around? The 5 shots groups will be telling.

Cheers

Thanks.
Wow, this is getting into "hot" loadings! I had previously avoided them to increase brass life. I HAVE had some pressure signs at these charge levels, just on hot days (85 F) -- yesterday was cool (60's 70's F).... Willing to give it a go a bit here; accuracy node should move to lower powder charges on summer days and I can adjust.

My next chance to try several loads won't be until next weekend or later.

Was not able to measure velocity--wind & shots knocked over my sun-diffuser. Perhaps we'll have a cloudy day by luck.

On the brass/velocities -- this is ironic to me. The only changes I really made were to
a) individually measure each load rather than using powder thrower
b) pay more attention to bullet seating depth (probably the key element, since I was loading right around the lands' depth)

Things do appear to be doing well, and I did think those last two loads' POI were nicely on top of each other!

I'll try the foulers at the same level and see what happens (that would be nice!).

The new Shilen match barrel should be on its way at some point.....things should be MUCH better then.

 

[Andrew Leigh]

Hi

The barrel may be an improvement but nothing like a problem to focus the mind on the basics again. Still 0.5" is nothing to be sneezed at many would give a delicate part of their anatomy to do that.

My first hunt this year is planned for 26th June to the 2nd July. I will need to get out onto the range myself soon.

I have 3 accuracy nodes on my 6.5mm but generally load to the the middle one. As we will be going for Springbuck (amongst others), I wanted to chase 120gr. in the 6.5mm hard to get minimal drop over distance. These are little buggers normally shot at 200m+.

Looks like you may have a node at 40.8gr.

I am a hunter so my loads genearally tend to be conservative, a nice slowish 180gr in the 30-06 and a 140gr slowish in the 6.5mm assures minimal meat damage. Not normally in favour of shooting a grain of rice at the speed of sound.