First Optimum Charge Weight test, Varget in AR 223

[gregj]

Attached target is 4 groups of 5 rounds each @ 100yds from bench, 25.1gr Varget, 69g SMK @ 2.260. Best group was 3rd from top, .647" / .618MOA. It a lot winder today than yesterday. I might not have been on my best game today either. Either way, this looks like a good load for my AR.

 

[helotaxi]

Curious how you arrived at 0.146" for that group.

 

[gregj]

That's what the OnTarget software calculated. I just double-checked it.

 

[Tim the student]

I got much more than that for that group. How are you figuring it?

It still is a good group that I'd be happy to shoot, but it sure doesn't look like .146".

 

[gregj]

You guys are right, it just hit me I didnt set a reference. Sorry, still learning the software. I'll recalc and update the post. Thanks for bringing my error to my attention.

(I feel like such a dummy :banghead: )

 

[helotaxi]

It happens. Being a natural skeptic helps sometimes.

 

[kelbro]

Looks pretty good. If you load up 10 at 25.0 and 10 at 25.2 and they shoot the same, you can confirm that it's an OCW load.

 

[gregj]

If you load up 10 at 25.0 and 10 at 25.2 and they shoot the same, you can confirm that it's an OCW load.

4 targets, 5 rounds each, round robin ? Will load them up and test next week. Thanks

 

[oldfortyfiveauto]

This is what I've been doing and it seems to work well. This target was done at 100yds, but I usually prefer to do the same thing at 200yds. I fire one shot per target dot. That way there is no confusion as to which shot is which. I usually do 8 steps from min to max recommended charge. With the grid lines it's easy to see how the bullet moves. All charges are weighed.

This particular rifle settled in at 21grs, which gave me a easy +/-0.5gr tolerance on the charge. Pretty hard to screw up the charge. Depending on how things go I also try the load at different bullet seating depths. Then I finish up with 4 to 8 five shot groups to verify for consistency.

The bottom line is typically within 8 shots or so I know if the bullet/powder combination is worth pursuing.

 

[kelbro]

4 targets, 5 rounds each, round robin ? Will load them up and test next week. Thanks

One target. 3-5 of each, mixed up. If it's OCW, it shouldn't matter.

 

[gregj]

If you load up 10 at 25.0 and 10 at 25.2 and they shoot the same, you can confirm that it's an OCW load.

Here's the target from today. First two are 5 rounds ea @ 25.0gr Varget, next two are 25.2gr Varget. Not sure about the vertical stringing on #3, I know my breathing was under control.

Comments/suggestions?

Spread:
.685"
.660"
1.040"
1.385"

 

[kelbro]

That tells me that you are close but that 25.1 is probably not your OCW. Maybe it's 25.0?? If you try 24.9, 25.0, and 25.1 and keep it under .75", you will then have a good, resilient load at 25.0.

A load that shoots well +/- .1gr is ideal as it accounts for powder measure inconsistencies and lot variations in powder and primers.

 

[gregj]

Thanks! I'll work them up and try again thurs am.

 

[gregj]

Here's the latest results. I think I'm nearing the end of my quest. 5 rounds each @ 100 yds, round robin, bags front and rear, Varget with 69gr SMK @ 2.260 Temp was about 40*, cloudy, calm.

Grain / Spread
24.9gr / .682"
25.0gr / .452" (.431 MOA)
25.1gr / 1.214

 

[arizona98tj]

gregj,
What is the size of the orange dots?

Edit: Never mind....I too was trying to determine where you were getting those very small numbers from....I now see that you have adjusted your software.

 

[kelbro]

Looking good. Now start tweaking your OAL.

Finding an OCW can be both good and bad. Seems like once I find one, I load up a couple hundred rounds, put that rifle in the safe and then start looking for another 'project'.

 

[gregj]

I'll try some variations from 2.260 to 2.250. Given I'm using a mag, cant go much longer, and not sure I should go shorter. Thanks again Kelbro.

 

[Captaingyro]

Finding an OCW can be both good and bad. Seems like once I find one, I load up a couple hundred rounds, put that rifle in the safe and then start looking for another 'project'.

I do exactly the same thing. It's like each rifle has a secret, and when I've figured out the secret, I move on to the next one.

 

[Clark]

There are a million guys doing a ladder test to find an accurate load.

That does not work for me. What ever best powder charge I find is not repeatable by me at a later date. So I give up.

I have low standards, low equipment, and low skills. I am happy with a big game rifle that shoots a 1" 3 shot group more than half the groups.
I am happy with a varmint rifle that shoots 0.5" 5 shot groups more than half the groups.

Bench rest competitors with $4k 6mmPPC rifles are operating at a higher level, and worry about things that have no effect on my situation.

Here are a list of things I do not do anymore for accuracy, because I do not see a benefit:

1) Find an accurate powder charge
2) True the action
3) weigh the brass
4) weigh the charge
5) turn the necks
6) de burr the flash hole
7) chase the threads
8) lapp the lugs
9) crown the muzzle

Things I can detect a tiny improvement, but probably not worth it.
1) 40X scope
2) glass bed the action
3) speed up the lock time
4) 1 ounce target trigger


Things that made a huge improvement:
1) Heavy barrel.
2) Clean barrel with no Copper fouling
3) keep skinny barrels cool
4) No wind
5) No expander ball
6) bullet touches lands
7) practice dry firing until cross hairs stay on bullseye
8) No shaky benchrests
9) use a rear bag with a bipod when prone
10) double check scope mount screws are tight

 

[kelbro]

As with many things, YMMV but there is a lot of wisdom in Clark's post. I have the same feelings about a lot of it but differ on some of the others. I won't elaborate on all of them but if you shoot A LOT and track the 'on target' results, you can't help developing some of the same opinions. But hey, some folks like to piddle and the only way you can find out if something works for you or not is to give it a try.

 

[gregj]

Thanks all for the input. I had a couple objectives for this endeavor, to learn more about developing a rifle load, and to see what else I can coax out of my RRA AR. I know it's still way more accurate than I am, but hey, it's fun trying to find the best load, and learn what I can along the way.

I thought I would focus on testing OALs next. Here are my results to date. It looks like the OALs to focus on next are 2.280 and 2.320. The round outside the group @ 2.320, I may not have followed through with the trigger, and may have pulled it slightly. It was brisk and windy today. I'll work up some loads around these two next.

5 rounds on each target, round robin, 100 yds, 25.0 gr Varget, 69gr SMK, PMC brass, CCI #400 primers.

The rounds at 2.360 were too long to be fed from mag, so they were dropped into chamber, pushed halfway in, and then released the bolt. This was the max OAL I selected as the distance to the lands is right at 2.365 All others were single fed from mag.

Tested 12/31/11
OAL / Spread
2.245 / .998"
2.250 / .989"
2.255 / .848"
2.260 / 1.019" (normal OAL)

Tested 1/2/11
OAL / Spread
2.260 / .843"
2.280 / .679" (4 @ .297" .283 MOA)
2.320 / .894" (4 @ .534" .510 MOA)
2.360 / 1.605"

 

[kelbro]

Try a Google search for mag mods that will allow you to load your AR at more than 2.26.

 

[oldfortyfiveauto]

From what I'm seeing here you guys are doing more work than necessary to get a good load. There also seems to be some misconceptions about ladder loads. If you can't get to a load that is repeatable and consistent, then you probably have a hardware problem; i.e. barrel, bedding, trigger, etc.

One of my Remington 700's was that way. I sent it back to Remington and they put in a new barreled action and returned it with a test target that was worse than I was complaining about. It still shot crappy. Finally rebarreled it with an older, but new Remington barrel and now it shoots.

You also have to ask yourself what kind of accuracy you are looking for. I want consistency and repeatability for prairie dogs. But a deer rifle only needs to shoot well for 2-3 shots. I've found most all rifles will shoot a good 3 shot group reasonably often, but constant 5 or 10 shot groups only come with some work.

This AR load is making some nice groups, but if you have to load to a tolerance of +/-0.1 of grain to do that you have a problem. It's difficult to produce lots of ammo to that quality level. Ladder loading will almost always give you a load that will work at +/-0.3 grains or more to work with. I can almost load them with a spoon. This type of load tends to be more forgiving in other areas as well. Both of my 223 bolt guns will work with their loads in pretty much any case I pick off the ground and any primer.