Perplexed with 5.45x39 AR

[ABNAK]

Synopsis: had a S&W MP15R complete rifle. Bought ~ 3K rds of Wolf 60gr FMJ. Put an Osprey piston on it and it worked fine. Decided to make an AR pistol so cut the barrel down to 11", recrowned and rethreaded, put a Vortex on it, and got a pistol buffer tube (of course also bought a new lower so it was all legal and such). Still used the Osprey but had to not only open up the gas port a tad but also cut a coil at a time from the buffer spring until it functioned properly (that is of course a fine line between less resistance and enough "oomph" to strip a new round and return to battery).

In the current ammo madness/idiocy I decided that I'd hold onto the 5.56 that I had and use the 5.45 as "training" to maintain proficiency. Therefore I wanted to convert the pistol back to a carbine. Ballistic Advantage had (in stock) a 14.5", midlength, pencil profile barrel that is nitrided. Put it on and perm-attached a BCM A2X extended FH. Moved the Osprey over once again. Also made sure the orange extra power hammer spring was in place.

Now, Ballistic Advantage says that a piston system may require opening up the gas port a bit. Figured I'd try it as is and see how things went.

Well............

Went to zero today, both irons and Aimpoint T1. Had bolt-over FTF, a few solid primer strikes but apparent duds, as well as short stroking and closing on an empty chamber. Also (disturbingly) couldn't extract an unfired round manually; if fired it would extract fine but on the "duds" I couldn't get it out unless I pulled back HARD on the CH while simultaneously gently prying the front of the bolt carrier back with a screwdriver. Started to get pissed........

Switched the buffer spring to the one I had cut down for the pistol AND opened a different case of Wolf just to see. No more bolt-overs or inability to extract an unfired round. However, still had a few "clicks" on an empty chamber and *apparent* duds, but overall much better.

First, is Wolf really that crappy and hit-or-miss from lot to lot that something as simple as manually extracting a round can be an issue? Also, are there that many duds? I'm talking solid primer strikes, and most of those fired on a second chambering.

Secondly, while I wondered if the cut-down pistol buffer spring would "overgas" the gun it is obvious that there is still an occasional eject-but-not-pick-up failure (the "click" on an empty chamber). I checked the tail end of the buffer to see if it was getting beat up and there wasn't a mark on it so even with the cut-down spring it is still borderline on impulse.




Right now I'm leaning towards Wolf being feces ammo.

[Todd.K]

No drop in piston system can possibly work optimally across every barrel length and especially different calibers. I'd consider it the most likely problem here.

I never consider cutting the action spring the right thing, it is too likely to cause feeding malfunctions.

See if it will run DI or as it's a training only gun, open the gas port with the piston until it runs with a normal spring.

[ABNAK]

No drop in piston system can possibly work optimally across every barrel length and especially different calibers. I'd consider it the most likely problem here.

I never consider cutting the action spring the right thing, it is too likely to cause feeding malfunctions.

See if it will run DI or as it's a training only gun, open the gas port with the piston until it runs with a normal spring.

I tend to agree, coupled with Wolf's inconsistent performance from one lot to another. And yeah, that cutting of coils walks a VERY fine line that one more might be enough to make it extract/eject but too weak to strip another round and go into battery. Rather precarious. However, I already had one from the pistol conversion so I figured I'd give it a whirl.

I'm gonna call Ballistic Advantage and see what size they recommend opening up the gas port to.

[MistWolf]

Once you open up the gas port there is no going back unless you get an adjustable gas block.

Wolf is steel cased and I believe the 5.45 is corrosive. Steel cases do not seal the chamber very well and allow gases to leak past the neck and leave residue. Clean the chamber thoroughly and with the right type of cleaner before opening up any gas ports. Clean the gas block thoroughly as well

Littlelebowski's thread on cleaning the 5.45- https://www.m4carbine.net/showthread.php?t=87949

[Littlelebowski]

I don't understand adding a piston to a "low cost training setup" but what is the most likely answer? Wolf 5.45 ammo won't run at all and you've uncovered the hidden truth of it or moving around that piston to different setups is not a good idea?

[Littlelebowski]

I'd convert back to DI, pronto. You've caused yourself all sorts of problems in what is a turn key setup.

[ABNAK]

I'd convert back to DI, pronto.

I've been thinking about it. Need to find a bolt carrier first, and in this environment it's slim pickins'! I can take one from another AR but then I'm still short one. IIRC the one I had I put with another 5.56 bolt and traded off some time ago as the Osprey comes with it's own carrier.

[ABNAK]

I don't understand adding a piston to a "low cost training setup" but what is the most likely answer? A)Wolf 5.45 ammo won't run consistently and you've uncovered the hidden truth of it or B)moving around that piston to different setups is not a good idea?

I think it's "C", all of the above.

[Clint]

I'd convert back to DI, pronto. You've caused yourself all sorts of problems in what is a turn key setup.

I have to agree.

With the proper size gas port, gas system length for the barrel and a heavier buffer, DI is an extremely reliable system.

[Suwannee Tim]

I assembled Adams Arms stuff into a piston 5.45, it wasn't long before I converted it to DI. The DI works perfectly, how can a piston top that? With DI there is no piston assembly that must be cleaned every time you shoot with corrosive milsurp ammo, a significant savings of time. I hung on to the AA piston stuff, I will make an SBR with it when my papers arrive, otherwise I would have sold it.