First Optimum Charge Weight test, Varget in AR 223

[gregj]

Would like options on my first attempt at an OCW using Varget in my RRA AR 20" Predator Pursuit, 1:8, RRA 2 stage match trigger, Millet 4.5-16 scope, bags front and rear, using 69gr SMK, OAL 2.260. All the brass was once fired PMC in my AR, except somehow I let 6 brass of other headstamp get into the mix. I dont think they skewed the results too badly though.

I fired two fouling shots first, using my normal load of 22.5 gr H335, same bullet, same OAL. I used the OnTarget Precision Calculator to determine the spread of each group. After shooting all the OCW test rounds, I fired two more fouling shots (I had them left over) of my normal H335. These 4 rounds had a spread of .809" (three almost in same hole).

For the OCW, 3 rounds each weight, round robbin, all rounds at 100 yds, temp 35*, no wind.

Looks to me like 25.1gr Varget is the OCW.

gr / Spread
23.3 / .751"
23.5 / .518"
23.7 / .604"
23.9 / 1.724"
24.1 / 1.272"
24.3 / 1.613"
24.7 / .823"
24.9 / .816"
25.1 / .508" (.485 MOA) <<<<
25.3 / .792"
25.5 / .679"
25.7 / .608"
25.9 / .695"
26.1 / .692"


Next, I plan on seeing how my current load of H335 compares against the Varget. (I really dont care for the Varget, as it goes through my powder drop like dirt!!)

 

[kelbro]

The 25.1 load does look good but are you sure you understand how OCW works? It's not the smallest group that you are looking for. You should re-read the process. Also, moving out to 200yds would give you more dispersion and eliminate some of the confusion from having so many groups clustered in the same general location of the target.

Had you shot 26.3, I would say your OCW is around 26.1. Funny thing is, that was my OCW for 3 different 223s shooting the same bullet.

 

[rcmodel]

Regardless of how many groups you shoot on one target.
(Which has nothing to do with anything anyway.)

You can't pick a load based on one 3-shot group out of 15 3-shot groups, shot in one setting on one target.

Nobody can shoot that many groups, or shots, without pulling a few shots, or getting so tired they can't concentrate well enough to shoot that many "perfect" groups.
That right there spoils the whole process and you have to start over again.

Or shoot more of each charge to level the playing field somewhat.

One 3-shot group with each load is statistically meaningless.

rc

 

[snuffy]

OCW is a bunch of hooey, it's supposedly a better version of the Audett ladder method, which in itself is smoke and mirrors too. They're a waste of components and wear and tear on the rifle and the brass.

5 shot groups shot over a chronograph AND at a target will tell you a lot more with the same amount of components. People have to keep re-inventing the wheel. The old ways still work.

 

[rjfunk]

RC and the others have it right. Take this as someone who was just there. I thought I had my load with one test. Was getting 1/2 moa groups in my first 3 shot tests with some charges (I was also doing OCW)! I was told repeat it to see if it holds. It varied a fair bit in different tests.

If you're looking for an moa up to 100 or 200 yard load, I think you have it. If you want more, you've got a lot more playing around to do. Enjoy.

 

[gregj]

Unfortunately, I am limited to 100 yds, as that is the most distance at any area range, within reasonable driving distance. So given this restriction, I am trying to learn how to improve my loads. I know I personally have a lot to work on as far as my skills, and will continue to work on them. But I do enjoy the challenge of trying to find the best load for my rifle, given my current distance limitation.

The range of loads I used, was based on my Sierra manual, 26.1 being the max load. 25.3 was their accuracy load.

I'm sure I dont fully understand OCW, but I have read and re-read it several times. I tried to replicate as I undstood the process, and the examples provided.

Guess it's back to the bench and the range.

 

[MtnCreek]

One 3-shot group with each load is statistically meaningless.

+1.

Try 5 shot groups on paper and keep in mind (1) 5 shot group does not mean much either; it has to be repeatable. When shooting over a chrony for variations, I use 20 shot groups.

BTW, ½” group @ 100yds is good shooting!

 

[Ky Larry]

No powder-bullet-primer- C.O.L.-charge weight is ever going to shoot exactly the same every single range trip. There are too many external variables. Wind, temp, humidity, fatigue, barrel wear, and bench technique will all affect group size. As a diabetic, I've found that my blood sugar level affects my eye sight which affects my shooting. Also, Varget and H-335 may not be the best powders for your rifle. I've had good results with both but I've found AA-2460 to shoot better in my .223 rifles.
Don't get discouraged if you don't find your "go-to" load immediately. Load developement is the fun part of shooting. The combinations of powder, case, primer, and bullet for a .223 are almost limitless. I have several very accurate loads. I have an old Ruger-77V twotone in .223 I bought in 1987. It's on its third barrel and I'm still finding new combinations. Some work, some don't.

 

[gregj]

Last night I loaded up 25 rounds of 25.1gr of Varget, and will shoot some 5 or 10 shot groups, along with 25 rounds of my usual 22.5gr H335. I just wanted to see a comparison between the two.

Santa will be be bringing me a Geissele SD-E trigger group for X-mas, which should help tighten my groups a little, but I wont be adding this variable into the mix just yet.

I'll try and pick up some AA-2460 this weekend and give it try over the holidays. I started this quest last winter. My warm weather weekends are usually spent at USPSA matches with my son, or practicing for an upcoming match. Now that the weather has turned cold, it's time to start the quest up again. Thanks guys.

 

[gregj]

Ok guys, another (dumb) question. Given my initial 3 shot group results, does it make sense to a) select 25.1gr as my potential optimum charge, and b) load 10 rounds at this charge, 24.9, and 25.3 for comparison?

 

[Captaingyro]

Everyone seems to be anxious to tell you what they think you're doing wrong, but no one has really attempted to give you a short and sweet explanation of how to do OCW correctly.

Your target contains valuable data, so let's teach you how to use it. First, as someone pointed out, forget about group size. What you need to compute is the geometric center of each group. That means pick a single point on the target which is the average of the three shots. You can do it right on the target, but sometimes it helps to plot these points on a separate piece of paper with duplicate targets.

When you've plotted these points, step back and take a look at the trend. As your charge increases from target to target, the centerpoints of your groups will move, sometimes erratically. But at some place in your series, you'll see about three targets in a row (possibly more) where the centerpoint is about the same direction and distance from the center. This means that, within that narrow range of charge weights, your results are very consistent (on average) and slight variations in charge won't have much effect on your bullet flight. Your OCW is the middle of that range.

Just eyeballing your target, it appears you have one node between 24.9 and 25.3. The centerpoints of those groups all seem to be at about 11 o'clock and 1.5 inches. You've got another node between 25.7 and 26.1. All of those seem to be centered about 10:30 and 1.7 inches.

You may have picked the correct OCW (25.1) but for the wrong reason!

Once you've found your OCW, you adjust for best group size by varying seating depth.

Expect some frustration, and some ambiguous results, but more tests and more data will eventually lead you to a pretty good load.

 

[W.E.G.]

I can recall reading in the gun rags through the ages that best accuracy is usually achieved at near "maximum" load.

Your 25.1 grains is right there.

(This data from Quickload. Subtract ~100 FPS for AR-15 actual velocity - as AR-15 has extra hole in the barrel)

 

[helotaxi]

Everyone seems to be anxious to tell you what they think you're doing wrong, but no one has really attempted to give you a short and sweet explanation of how to do OCW correctly.

Your target contains valuable data, so let's teach you how to use it. First, as someone pointed out, forget about group size. What you need to compute is the geometric center of each group. That means pick a single point on the target which is the average of the three shots. You can do it right on the target, but sometimes it helps to plot these points on a separate piece of paper with duplicate targets.

When you've plotted these points, step back and take a look at the trend. As your charge increases from target to target, the centerpoints of your groups will move, sometimes erratically. But at some place in your series, you'll see about three targets in a row (possibly more) where the centerpoint is about the same direction and distance from the center. This means that, within that narrow range of charge weights, your results are very consistent (on average) and slight variations in charge won't have much effect on your bullet flight. Your OCW is the middle of that range.

Just eyeballing your target, it appears you have one node between 24.9 and 25.3. The centerpoints of those groups all seem to be at about 11 o'clock and 1.5 inches. You've got another node between 25.7 and 26.1. All of those seem to be centered about 10:30 and 1.7 inches.

You may have picked the correct OCW (25.1) but for the wrong reason!

Once you've found your OCW, you adjust for best group size by varying seating depth.

Expect some frustration, and some ambiguous results, but more tests and more data will eventually lead you to a pretty good load.

On-Target from Berger can help plot all this out for you and eliminate a lot of the guesswork.

 

[kelbro]

Captaingyro gave a very good explanation.

FWIW, I have used this method on 8 or 9 rifles and it worked on all but one of them. To be fair, I sold that one before I was able to spend much time on it.

I think that a lot of people discount the OCW method without really understanding it. They try it and it doesn't give them the results that they expected. My luck has been good with it.

 

[wanderinwalker]

gregj,

Aw geez, you could have short-cut the Varget/69gr Sierra load work-up and asked a bunch of Highpower shooters. It's 25.0gr of Varget and a 69gr Sierra and go shoot... :banghead: Start at 24.5 and work up, but you've done that. And don't use Winchester primers, the brass colored ones will pierce.

Having never done the OCW method myself, my understanding is that you are attempting to find a node where slight changes in charge weight give negligible changes on the target. Basically, you could set your powder measure to throw 25.1gr of Varget and even if it's 25.0 or 25.2, those changes aren't going to completely blow you group. (Somebody correct me here if I'm wrong. I will also add I absolutely will not tolerate a load combination that is so fussy it has to be trickled to exact weight.) Part of the reason many shooters like extruded powder is some of them seem to have a wider sweet-spot for accuracy.

 

[TexasShooter59]

gregj: I have done a couple of OCW series on .223. What I did was to run increments of 0.3 grains on the first one. Then, narrow down to a couple of nodes. Then I would do another set with 0.1 grains with the "center" of each node in the middle of those charges. (hope that makes sense!)

snuffy: What technique would you use? I'm not being a smart aleck; I am interested because I want to work up a magnum load and want to keep the expensive components and recoil to a minimum. I do not want to use OCW or ladder with this test.

 

[snuffy]

snuffy: What technique would you use? I'm not being a smart aleck; I am interested because I want to work up a magnum load and want to keep the expensive components and recoil to a minimum. I do not want to use OCW or ladder with this test.

The time honored method of choosing a load from a manual, figuring the increments you want to try, then loading 5 rounds at each increment. Then firing those 5 rounds at individual targets.

Suppose a load has a powder spread of 52.0 to 58.0. What I do is throw out the lower half of the load data, load beginning at 55.0 and end at 58.0. Using 1.0 increments will result in 4 loads X 5 for 20 bullets. I most always set up my pact chrono to test velocities at the same time I'm shooting groups. I use a caldwell "rock" front tripod rest and sand bags in the rear, set on a heavy wood bench on concrete.

There should be one group that substantially smaller than the other three. You may want to repeat the process by loading some more on either side of that best group, maybe slim it down to .3 increments looking for the best of 3-4 more tests.

This would be for a cartridge in the .308 class of shell capacity. .223 would require much smaller increments, maybe as small as .3 grain increments.

If a rifle and cartridge is new to me, I would start lower in the load range because Max in the book might be over max in the new rifle. Makes no difference if the rifle is older than I am, it's still new-to-me.

Using the chronograph, you can see the increase in velocity as the charge increases. If the increase levels out IOW goes up less per increase in powder weight, you're running into pressure. Push it too hard, the velocity can become less, even though there's an increase of powder charge! You've gone over the burn rate of that powder.

 

[gregj]

Snuffy:

This would be for a cartridge in the .308 class of shell capacity. .223 would require much smaller increments, maybe as small as .3 grain increments.

I assume you meant .1gr increments for .223 instead of .3?


wanderinwalker:

Aw geez, you could have short-cut the Varget/69gr Sierra load work-up and asked a bunch of Highpower shooters.

I thought that's what I was doing??

It's 25.0gr of Varget and a 69gr Sierra and go shoot...

I assume this accepted load is for a 1:8 barrel.

I think my next step will be as wanderinwalker and TexasShooter59 suggested, and try 25.0, 25.1, 25.2 next. Then I'll start varying OALs.

Thanks all for the input!

 

[snuffy]

Snuffy:
Quote:
This would be for a cartridge in the .308 class of shell capacity. .223 would require much smaller increments, maybe as small as .3 grain increments.
I assume you meant .1gr increments for .223 instead of .3?

Nope! I've never gone under .3 for anything, not even the tiny 22 hornet. If I can't see a "node" with .3, that load combo just isn't going to work. We're not talking benchrest here. At least I'm not. I'm talking powder charges thrown with a measure once I have a load, and I'm using a pretty much stock bushmaster,(as far as the barrel goes). I do have a jewel trigger and fiber fore-end, 4x picitinny gas block, Nikon 4.5 x 14 x 50 scope.

You're talking about trickled charges to get down to .1 difference. Most rifles won't know that small a difference. I do have the pact dispenser system that can fine it down to .1 increments, but that would slow down production too much. I run my .223 on a dillon 650, using a Hornady measure in a case activated die.

A good bolt gun would be another subject entirely. Or even one that's been assembled by a gunsmith that knows how to blueprint an action with a carefully cut chamber in a good barrel blank.

Expecting a run-of-the-mill-factory gun to perform to benchrest standards is wishful thinking.

 

[TexasShooter59]

The time honored method...

Thanks, I appreciate it!

 

[beatledog7]

You're talking about trickled charges to get down to .1 difference. Most rifles won't know that small a difference.

A 0.1 grain change might as well be no change.

For example, you can have that much in variance (say 24.95 to 25.05) and still have the scale say 25.0gr.

Even with a 2.0gr charge of some really fast handgun powder, 0.1gr is just 5%, a difference that 99.5% of shooters won't be able to detect.

 

[gregj]

A 0.1 grain change might as well be no change.

Not sure if my results today will agree with that. I tested a few more loads of Varget this am, and for the first time, I had 5 rounds all touching @ 100 yds! I'm going to load up 20 @ 25.1 and see if I get similar results.

gr / Spread
25.0 / .293"
25.1 / .097" .092 MOA <<<<<<
25.3 / .141"

 

[NeuseRvrRat]

looks like 25.1 gr with that bullet should be good enough for any hunting or plinking duties

 

[Tim the student]

Not sure if my results today will agree with that. I tested a few more loads of Varget this am, and for the first time, I had 5 rounds all touching @ 100 yds! I'm going to load up 20 @ 25.1 and see if I get similar results.

Yup, repeatability is key.

 

[helotaxi]

One group doesn't mean a thing. If you've actually found an OCW node, 0.1gn really doesn't mean a thing. That's the whole point of OCW, you have a load that isn't terribly sensitive to a couple tenths of a grain variance in powder charge.