My 5.56 testing

[Ponder_MD]

I have a 16" 1x7 twist barrel. I made up 3 small batches of cartridges using 62gr Hornady (3037B bullets) and H335 powder. 3 velocities. I shot at a 3" target at 100 yards using a 1x6 optic.
Some weirdness ensued but I think I'm on solid ground.

- The first and slowest batch made an acceptable grouping, about 1.5 MOA.
- The second batch was mid-velocity and had a wild flier and 2 faulty primers. I used CCI #41 military primers. One cartridge fired on the second attempt, one absolutely failed. Lousy grouping.
- The third and fastest batch made a slightly sub-MOA grouping.
- I shot a 62gr commercial batch as a "control." My 3rd/fastest batch was equal or slightly better than the commercial ammo.

The faulty primers really surprised and irked me.

 

[chriskat]

The primer thing is odd. How many in a small batch? I don't bother with military primers in AR's, M1's or M1 carbines. Generally use Winchester of whatever size.

 

[chilipeppermaniac]

The primer thing is odd. How many in a small batch? I don't bother with military primers in AR's, M1's or M1 carbines. Generally use Winchester of whatever size.

WINCHESTER Small Rifle?

 

[John from MD]

Are you using an original AR15 type fire control system? If not, your hammer spring may not set off a #41 primer.

 

[Rockzilla]

Hmm.. faulty primers.thats interesting
All the same primers for all load development?
Primers consistent seating? Pockets cleaned? One round fired on second attempt? Possibly not seated fully, first attempt seated the primer more, second attempt it fired.
Load details, please. Are you using a Chrono for your data? To obtain your velocities?
What were the charge weights for the 3 loadings.
Just asking questions....

No AR expert..there are some here who are.
But hammer spring, firing pin protrusion, etc
May not have enuff force to ignite the primer

As mentioned above, I've never used any military primers, its either CCI-200's or 400's
for "decades" various semi platforms. No issues, but..then again now that I mentioned it that may change. Have used Winchester / Remington small rifle no issues either.

But as mentioned earlier about the primer not fully seated, I have run across that, where it took more than one attempt to set it off. Re-adjusted some things, me, the press. Even used the old LEE Autoprime to check a few, yeah I know bad idea, loaded rounds, but mainly had to do with the primers not seated correctly. Or and to just "throw" this out there, primer contamination, oils, cleaners etc. Just a thought

-Rock

 

[Uncle Duke]

I suspect primer seating depth as being the most likely culprit.

 

[Rockzilla]

I suspect primer seating depth as being the most likely culprit.

^^^ agreed..
Just happened to remember there was a discussion in another thread about difficulty in seating primers,.plus removing crimp, etc.
What you mentioned just now and remembered your name, the "lite bulb" came on a little dim but came on.
Post #4149 in the "What did you do at your bench today" outlined the details by OP in seating primers.
Suggestion would be start with new load development. Start fresh..Use the current ammo as plinking.

-Rock

 

[Ponder_MD]

I suspect primer seating depth as being the most likely culprit.

too deep or not deep enough? The dimple from the firing pin was deep, especially after 3 tries.

 

[Ponder_MD]

Information:

- Yes, same primers for all rounds.
- Bravo Company ACT for my trigger group.
-Primers seated using my Rock Chucker. I do my best not to touch them with my fingers at all. (oils and dirt)
- 3 batches of 5 rounds each, plus 5 commercial rounds of 62gr.

22.2gr of H335
23.3gr of H335
24.4gr of H335 (all per the Hornady Reloading Guide)

- I visually and tactile inspected all primers to ensure that they were slightly below flush with the case.
- I do not own a chronograph

All I can say is that this was the first dud I've ever experienced with this rifle so either I got a few faulty primers or I seated them improperly.

 

[trickg]

What rifle were you using?

I don't know about anyone else here, but I'm not sure I could shoot a sub-MOA group at 100 yards with a 6x optic, and I sure as heck can't do it with an AR.

What was your rifle setup? What kind of rest were you using? Just typical range bench bags? What was the wind like?

Seriously - I can shoot sub-MOA with my precision rifle at 100 utilizing my 5-25x scope, but that rifle is designed to do it. If you're getting sub-MOA with an AR type rifle at 100 yards with a 6x scope, you're a heck of a lot better shooter than I am.

 

[Ponder_MD]

What rifle were you using?

I don't know about anyone else here, but I'm not sure I could shoot a sub-MOA group at 100 yards with a 6x optic, and I sure as heck can't do it with an AR.

What was your rifle setup? What kind of rest were you using? Just typical range bench bags? What was the wind like?

Seriously - I can shoot sub-MOA with my precision rifle at 100 utilizing my 5-25x scope, but that rifle is designed to do it. If you're getting sub-MOA with an AR type rifle at 100 yards with a 6x scope, you're a heck of a lot better shooter than I am.

I'm using a rifle that I made out of Del-Ton parts with a PA 1x6 optic. 16" barrel.
There was little to no wind.
I was using a "hard" bench rest that I borrowed out of the gun club closet. It's just a little metal tripod with an adjustable jackscrew and a "V" for the barrel.

I'm not putting bullets through the same hole, but they're very close together.
The mid-velocity batch was wild even without the faulty primers. Like, several MOA's. Not sure what happened there. Maybe my charges got screwed up.

Question: Do you shoot 3 or 5 rounds when evaluating a group?

 

[Rockzilla]

too deep or not deep enough? The dimple from the firing pin was deep, especially after 3 tries.

Bad primer or if using the Rock Chucker priming system, there could be some residual oil from the plug that seats the primer. Just thinking out loud. Gonna still have to go with seating. With the comments about the "second batch" something in the process changed. This may sound like a big Pita..but weigh every charge, then shoot, if you are using a powder measure, you want consistency from stop to stop, some double tap as they hit each stop, not hard, lightly
Look at the primers after you primed are they flattened, from to much force or do they still have the rounded edges.? Some people get carried away, and with the linkage on the Rock Chucker you can apply to much and not realize it. I use some of my Rock Chuckers for bullet making / swaging sometimes using 22LR cases to make 22 cal bullets or using copper jackets to make bullets. So with the leverage, and all. Went to the off press priming, using the old Round tray Autoprimes. Better feel, and if it dont feel.right .stop there is a reason

development wise is 5 rounds per powder step, mostly all my testing is with 5 rounds. Now the powder increases/ amounts would be depending on case capacity. It wouldn't be practical to do 1.0 gr increments in say a 338LM or a 17 Remington. Now once a load was developed and starting to dial in say in the 338LM fine tune it. The 220 Swift was .3 once I achieved the results, then down to .1
But we're talking 5.56 here. Sure don't know it all, everyday is a learning experience. Sometimes the answer to the problem is right there in front of us, we tend to "over think" things, some of it is obvious. Me in that case is walk away, go do something else, something different, come back with a clear mind, start from scratch. Just an opinion.

-Rock

 

[Park ranger]

I suspect primer seating depth as being the most likely culprit.

This

 

[trickg]

I'm using a rifle that I made out of Del-Ton parts with a PA 1x6 optic. 16" barrel.
There was little to no wind.
I was using a "hard" bench rest that I borrowed out of the gun club closet. It's just a little metal tripod with an adjustable jackscrew and a "V" for the barrel.

I'm not putting bullets through the same hole, but they're very close together.
The mid-velocity batch was wild even without the faulty primers. Like, several MOA's. Not sure what happened there. Maybe my charges got screwed up.

Question: Do you shoot 3 or 5 rounds when evaluating a group?

I shoot 5 rounds. IMO it's a better indicator of both the accuracy of the round and my skills as the shooter.