Need advanced advice/help: AR Pistol reloading issue

[Uncle Ed]

Below are a Wilson, Dillon, and a JP Enterprise case gauges with .223/5.56 cases put in base first. And the Wilson and Dillon gauges are at or over max SAAMI case diameter. The JP Enterprise gauge is closer to SAAMI minimum diameter. And if the resized case and loaded round passes a plop test in the JP Enterprise gauge it will chamber in any AR15 rifle.

Below a "FIRED" Lake City 7.62 case in a Dillon case gauge and showing its larger diameter.

Below the same "FIRED" Lake City 7.62 case in a JP Enterprise gauge.

Meaning even if the case shoulder has been set back .003 to .006 the case body may drag on the chamber walls. And the case shoulder may not be touching the shoulder of the chamber. And the cartridge may need a second hit of the firing pin to make it go bang. And range pickup brass fired in another chamber will spring back after sizing and may cause problems. And the OP is using range pickup brass that is causing his problems.

Bottom line, a full length resized case should be .003 to .005 smaller in diameter than its fired diameter. This allows the cartridge case body to chamber without binding. And also allows the case body to spring back from the chamber walls and extract reliably.

 

[Knotwild]

If you haven't already (I didn't see that you did) I suggest a small base sizing die.

 

[Uncle Ed]

If you haven't already (I didn't see that you did) I suggest a small base sizing die.

Ex Boy Scouts are always prepared for any type rifle.

NOTE, the black RCBS box below is a small base die, and I size all my once fired brass with this die for my AR15 rifles.

The Lyman type "M" expander below is like having Uniroyal Tiger Paw tires, they grrrip your bullets.

 

[Knotwild]

Ex Boy Scouts are always prepared for any type rifle.

Sorry about that, I didn't know you were the original poster.

 

[skiutah02]

If you haven't already (I didn't see that you did) I suggest a small base sizing die.

It's in there, I did try small base die, but thanks for the try.

 

[skiutah02]

A lot of cycling issues can be solved with correct weight buffers and recoil springs. With the pistols it seems they do better with heavier weight buffers.
And sufficient lubrication..
Most AR's (85% or better) that come into my shop with cycling issues are solved with lubrication especially brand new builds.

Www.sprinco.com
Www.heavybuffers.com
It takes time and effort but I would bet your ammo is not main issue

OK, thanks.

 

[Twdmar]

Drew,
I know you know how to load ammo and troubleshoot. If the headspace is ok, the firing pin is correct spec is it possible the hammer spring is too weak? Or if it's a cheap lower could the location of the pins be out of spec and cause in improper hammer strike. Try that lower on a different upper that you know works.
You've done everything else. What happens if you load some bullets long and jam them slightly so you know the case head is firmly seated against the bolt face?

 

[mgunderson]

This is fun to read. I will be surprised if we find it to be your reloading!

 

[Metal God]

This is fun to read. I will be surprised if we find it to be your reloading!

It is the reloading . If factory ammo works fine there is no other cause but the reloaded rounds . I've not read everything in this thread because many of the things suggested I believed were not the issue so If that's what the poster was saying I skipped it .

I believe it is the pistol has a small/short chamber and the OP is not bumping the shoulder back enough . Looks like to me you are just short of full battery and getting FTF . When you let the BCG fly home the momentum of the bolt slamming the case into the chamber is bumping the shoulder that extra .001 to .002 you need to go into full battery allowing the gun to fire .

I've tested this and purposely sized cases a tad long to see if letting the BCG fly home would actually set the shoulder back . My results showed that the shoulder will be set back anywhere from .0005 to .0015 every time you repeat the process . It continued until I had a total of .0035 of set back from my original base to datum measurement when chambering the same round over and over again .

First I'd check the factory ammo's base to datum measurement and compare that to my reloaded cases . You will need your reloaded cases to be at least as short head to datum as the factory ammo . Take your small base die and screw it down to allow for full hard contact or hard cam over . If that does not work put a shim/feeler gauge of .002 under the head of the case while in the shell holder and resize the case again this will bump the shoulder even more then the die will allow normally . Remove the decapping pin or you'll poke a hole in the shim

 

[Scott Harris]

A lot of cycling issues can be solved with correct weight buffers and recoil springs. With the pistols it seems they do better with heavier weight buffers.
And sufficient lubrication..
Most AR's (85% or better) that come into my shop with cycling issues are solved with lubrication especially brand new builds.

Www.sprinco.com
Www.heavybuffers.com
It takes time and effort but I would bet your ammo is not main issue

^^^^^^^The voice of experience here. pistol AR...probably a cycling issue. Rifle length gas systems work flawlessly. Short carbine-length can be very finicky.

PS. since you are using a small base die ans sizing it well, I doubt it is a sizing issue.

 

[Oleg S]

A lot of cycling issues can be solved with correct weight buffers and recoil springs. With the pistols it seems they do better with heavier weight buffers.
And sufficient lubrication..
Most AR's (85% or better) that come into my shop with cycling issues are solved with lubrication especially brand new builds.

Www.sprinco.com
Www.heavybuffers.com
It takes time and effort but I would bet your ammo is not main issue

^^^^ Keith knows what he’s talking about. He build and fixed quite a few AR’s.

 

[Nick Caprinolo]

Sounds like the round is not completely seated in the chamber.

Using a small base die, requires you run the ram all the way up, and screw the die till it is snug against the ram. Then you lover the ram and turn the die in another half turn. When you run the back up, you will feel a bump.

The cartridge in an AR is not fully seated in the barrel and this causes the lower part of the brass to expand.

Notice that you won't be able to reinsert a fired piece of brass in you chamber until it has been formed in your die. In a bold action rifle the cartridge is fully supported by the chamber and is fireformed, which allows you to just neck size if you desire to.

The light strike you are seeing on the primer simply be the primer going forward when the bolt stops, which will make a slight indentation on the primer. With the cartridge not fully seated in the chamber you won't be able to pull the trigger but when you extract the cartridge, you will see a slight impact from the firing pin.

 

[Metal God]

FTF

Oh , failure to feed.... I read it as failure to fire . If it has cycling issues it can be all kinds of things in a pistol . I'm still perplexed about factory ammo working and not the reloads . Still sounds like a sizing issue .

 

[dellet]

Have you checked headspace and a sized case for fit?

By that I mean a stripped bolt, sized case in the chamber and bolt will rotate into position? This should also pick up a case that is tight or sticking in the chamber wall.

Will an empty sized case w/bullet chamber?

Measure a factory round base to datum before and after chambering. Look for a collapsed shoulder.

Are your handloads compressed or 100% density?

A factory round with low powder fill has room for the shoulder to compress. A handload with higher density may not. If I under stood correctly, the handloads where the bolt was dropped from lock position, fired More often. It’s possible that more carrier speed is setting the shoulder back allowing full battery.

If the bolt is not fully into battery, it is not firing by design.

 

[Nick Caprinolo]

Have you checked headspace and a sized case for fit?

By that I mean a stripped bolt, sized case in the chamber and bolt will rotate into position? This should also pick up a case that is tight or sticking in the chamber wall.

Will an empty sized case w/bullet chamber?

Measure a factory round base to datum before and after chambering. Look for a collapsed shoulder.

Are your handloads compressed or 100% density?

A factory round with low powder fill has room for the shoulder to compress. A handload with higher density may not. If I under stood correctly, the handloads where the bolt was dropped from lock position, fired More often. It’s possible that more carrier speed is setting the shoulder back allowing full battery.

If the bolt is not fully into battery, it is not firing by design.

I know of no powder that would compress a load in a 223 round unless you were trying to use a long heavy bullet and seating it to SAMMI specs. In most cases putting enough powder in a 223 to compress a load in 223 would blow the rifle apart.

The OP has stated he has no problem with factory rounds. That only leaves his loading process as suspect. A pair of calipers could easily solve his problem. I wonder if he is trying the various solutions that have been offered here.

 

[dellet]

I know of no powder that would compress a load in a 223 round unless you were trying to use a long heavy bullet and seating it to SAMMI specs. In most cases putting enough powder in a 223 to compress a load in 223 would blow the rifle apart.

The OP has stated he has no problem with factory rounds. That only leaves his loading process as suspect. A pair of calipers could easily solve his problem. I wonder if he is trying the various solutions that have been offered here.

They are plenty of compressed loads that will fit a 2.260 length. I would offer Varget as an example.”

Its an AR pistol, it is most likely over gassed. That automatically points at the base diameter.

 

[Metal God]

Just about all my match 223 loads are compressed .

 

[rebel]

All my 3031 loads for 223 are "crunchy". OP, dellet troubleshoots for a living and knows his way around an AR and its many configurations. I think he is on to it.
For what it's worth .........

 

[Depart123]

Lots of posters here not bothering to read the OP.

 

[Metal God]

The OP said he measured the cases in a case gauge and brought the reloaded rounds to factory dimensions. Although that sounds self explanatory, it may not fully describe what he has done .

When measuring with the gauge did he actually measure with calipers or just observe where the case head sat in relation to the steps ? Observing is not as accurate as actually measuring as described in this video .

I prefer comparators like the Hornady or Sinclair