Need advanced advice/help: AR Pistol reloading issue

[skiutah02]

Slightly embassased to even ask for help, but this one really has me scratching my head.

Put together a fun 223 pistol. My first AR build from parts. Thought it would be a fun project.

You'll want to read all of this before giving me a knee-jerk answer as I probably have tried most everything obvious that I can think of.

Shot 5 round of factory ammo. No issues. Tried some reloaded ammo (for my AR rifle). About 75% ftf. Tried 10 more factory rounds of federal 55 gr ammo. Worked perfectly. Changed course and reloaded some range brass to meet the specs of the unfired factory ammo. Also issues. Reloaded the factory brass fired in that chamber. Still about 75% ftf. About 25% of the 75% ftf would fire if I manually loaded into chamber and closed bolt from locked open position. Changed primers. Same. Swapped BCG from my other rifle. Same problem. Put BCG in my other rifle worked fine with reloads. Swapped lowers, same problem. Swapped firing pins. Same problem. Took ftf rounds and put in AR rifle all fired/cycled even after 3 primer hits in pistol. Bought small base fl sizer. Didn't help. Cleaned and lubed BCG, fp, bolt. Changed bullets/brass/primer/powders/dies. No joy.

So I'm here. Pistol only works with factory ammo and is unreliable with reloads. Even reloads of brass fired in that chamber and reloads that work in two other ARs and three other barrels.

I'm sure there is other stuff I have tried but forgot to mention. Any other thoughts?

I feel pretty strongly after methodically moving suspected parts/components that it is the barrel, but I cannot for the life of me think how factory ammo works flawlessly (75 rounds 0 issues) but reloads do not work even if brought back to the dimensions of factory brass.

Thanks,

 

[jepp2]

Many things you haven't covered.
- what do the impressions of the firing pin look like on the primers of the brass that didn't fire in your pistol?
- what is the case head to datum length on the brass that did fire in your AR pistol? And how does that compare with the fired brass in your AR rifle, and the factory loaded ammo.
Let's start with that.

About 25% of the 75% ftf would fire if I manually loaded into chamber and closed bolt from locked open position.

Really not supposed to load this way, potentially increases the risk of a slam fire without the chambering action stripping the round from the magazine. For these rounds, if you separate the upper from the lower (or swing it open) can you close the BCG with your finger shoving it forward to chamber the round? Is your bolt fully closing on these rounds?

 

[skiutah02]

There is a clear firing pin hit on most of the primers. On about 10% the first hit is a bit lighter impression than it should be imo. But when retried a better hit. The it fires ok in the other rifle.

The factory brass is 1.751 to datum
The pistol fired ones are 1.753-54
My other AR is 1.754-55


The bolt does seem to close well and the forward assist does not move it at all.

Had not tried the separation and BCG closure by hand. A good suggestion. Will when I get home.

Thanks

 

[Uncle Ed]

Since your ammo fired the second time I would guess your primers are not fully seated.

The primers should be seated with a slight preload on the anvil.

 

[Falfan2017]

Are you using crimped primer pocket brass like lake city? If you are reloading that without fixing the crimp by swaging or reaming it sounds like the primers aren’t fully seated.

 

[skiutah02]

Since your ammo fired the second time I would guess your primers are not fully seated.

The primers should be seated with a slight preload on the anvil.

I've actually been thinking the opposite. Seated too deep or cup too hard (450) Conveniently a new CPS seater arrived and I can control that now. But seems a bit overkill for an AR pistol.

 

[skiutah02]

Nope brass is fiocchi, ppu or fc so far.

 

[Falfan2017]

Nope brass is fiocchi, ppu or fc so far.

I believe fc is crimped too. Ppu May be as well

 

[skiutah02]

I believe fc is crimped too.

If the FC had a crimp I removed it before reloading for my other AR but that was loaded 3-4 years ago. I only tried FC for the original reloads after the very first 5 factory shots then moved to GPL. The other 100+ have been Fiocchi (GPL) with 5-6 PPU for a different try

 

[Ned Ludd]

I don't have a direct answer to your question Drew, but just thinking out loud here. If I understood your post correctly, factory ammunition has always fired, reloads have a significant FTF rate. In the most simplistic terms, it seems then as though there must be a measurable difference between the two. Have you taken and compared measurements up and down the length of both types of loaded rounds, as well as the more obvious BTS dimension? I understand you tried a small base die, but that won't necessarily cover the entire case. Another thing you might try is to empty out a few of the [unfired] loaded factory rounds, removing the powder, primers, and bullets, then reload the [unfired] brass with your components and see if the [re-loaded] brass fires. If it is solely some aspect of the external brass dimensions, I would expect [re-loaded] virgin factory brass to fire with your components exactly like it did straight out of the box. Good luck with it!

 

[Highpower-FClass]

Drew, you have tried a lot of the things I could think of but out of curiosity, have you gauge checked the headspace in the AR pistol? Since the only common factor seems to be the barrel in the AR pistol, perhaps the chamber is too generous causing the reloads to sit too far forward in the chamber / being nudged forward by the firing pin, causing the anvil not to be struck sufficiently for ignition.

I am not sure as to why that would not affect factory ammo, other than perhaps the FL resizing making the base, or some other part of the case smaller than on the factory ammo. Some minute difference which causes the reloaded rounds scoot just a smidge further forward in the chamber where the firing pin cannot get a proper anvil strike.

 

[Ggmac]

Check your sized reloaded ammo in a go /no go gauge . Wilson sells the , teasonable . Worth every penny . You drop in your ammo , its either flush , deep or long

 

[Rustytigwire]

Wilson gauge

 

[Dusty Stevens]

If you like you can mail your barrel to me and ill give it a checkout and proper chamber finish. I think thats your issue. Ive seen it before- on parkerized/chrome lined barrels mostly. No charge with return shipping included of course. The barrel is your only issue it seems and it can be hard to figure out just why

 

[skiutah02]

Some good responses thank you.

Greg: I'll decompose and recompose a round or two per your suggestion. I've been so sure that it's the brass since the rounds fire in my original AR didn't think about this option. A good one.

Fredrick:. Without casting the chamber I've been left with measuring one fired virgin brass to approx the dimensions and perhaps this is too simple. I agree with many that it is probably the chamber, just cannot figure how factory work when resized back to factory dimension (measured) doesn't.

Wilson Case Gage crowd: I own and have checked the reloaded ammo with my Wilson Case Gage. I agree worth every penny, but not helping solve my mystery this time.

Dusty a mighty generous offer and I may take you up on it if this can't be figured out, but the barrel was about what shipping would be.

 

[Coyotefurharvester]

You have cross checked the lower, bcg and the reload components. You have to check headspace as mentioned. 20 bucks round trip priority mail to Dusty, send the bolt with.

 

[Sandstorm]

I like Dusty's idea...its in the barrel or a combo with the primers..Your firing pin may be shorter than the one in your rifle as well. Never mind that you swapped bolt carriers,,%*^@@
Just something else to think about...I have built a few of them but thats a new one on me..

 

[GuitarmanNick]

When reloading for any semi-automatic firearm, you should full length size your brass to insure reliable feeding and that your bolt will close. Neck sizing cases should only be done for bolt guns!

Definitely check your hand loads with a case gauge. If it passes the plunk test and does not chamber, then look at the rifle.

I have not experienced issues with my hand loads in any of my ARs, and rarely shoot factory ammunition in any of my tools.

 

[TheOtherZilla]

Here's my take. Have you tried resizing with a small base die?

 

[Richard Coody]

Two suggestions. Compare headspace and check case dimensions at intervals from base to shoulder between your sized brass and a factory round. That should identify your problem.

You have a perfect case gauge. Separate your.upper and lower, best if you remove the extractor, take a piece of your sized brass, not loaded round, and put it in the chamber. You should be able to close the bolt with just thumb pressure.

If not then your headspace is too long or your die is not sizing the base enough.

If it.chambers easily you may be setting the shoulder back too much and the firing pin can't ignite the primer.