Getting Tula 75 gr. HP to run in PSA upper

[TwoEyedJack]

I recently got a new upper from PSA with a 20" FN barrel. It prints the Tula 75 gr. HP rounds into pretty nice groups. The problem is that every other round fails to chamber. I think it is pretty close, since the hammer is usually cocked. I tried hosing down the bcg with rem oil to no effect. I also cleaned the chamber. Any tricks to getting this round to run? This upper has only about 200 rounds through it. Maybe it just needs to break in?

 

[Ditch-Tiger]

It very well might just need to be broke in.
I would also try some FMJ's and see if they feed better as the flat on the HP might be catching on a small lip where the extension feed ramps meet the lowers feed ramps.
I have a rifle that does this with HP's and USGI mags. Feeds fine out of magpul mags though. They must sit a hair higher in the lower.
Any way, you've now got 3 things to try.

Mags
Ammo
Break in the rifle

 

[helotaxi]

I have the same upper and have run almost nothing but handloaded 75gn Hornady HPBT through it without so much as a bobble.

Hard to help diagnose without knowing exactly what it's doing. Is it short stroking? Is the mag known to be good? Is it overriding the top round completely or trying to strip it from the middle of the case and jamming?

 

[TwoEyedJack]

Here is what happens. I am using a Colt 10 rounder since that is the only thing that does not stick down too far to preclude usage of my Outers rest. I pull the trigger, gun goes bang. Pull the trigger again, gun goes click sometimes, sometimes the hammer is not cocked, and sometimes it goes bang again. I have not had any failures to eject. It feels like the round may not have enough gas volume to work the action, but this is conjecture.

I got a 20 round Pmag today to try out. These rounds are on the verge of hitting the front of the mag.

 

[helotaxi]

As long as they don't hit the front of the mag you're OK. No factory rounds should be an issue in that regard.

It does sound like it's short stroking. Have you tried any other ammo? How does it run with quality fodder?

 

[husker]

I dont care what Russian ammo I run in my Colt sporter. I have the same cycle probs as you.
I have run 1000 & 1000 of PMC bronze without one hiccup,& all my reloads as well.

 

[Stack]

Full auto bolt carrier? H2 or H3 Buffer? What buffer spring are you running? IMHO rem oil sucks for the bolt carrier rails. Try something a little heavier. Of course that probably wont have any effect on the short stroke problem. What do your feed ramps look like? M4 extended? Rifle or carbine stock? The whole thing has to work together.

 

[helotaxi]

Feed ramps have nothing to do with a short stroke, but the PSA upper has them. It sounds to me like it is an ammo problem, not a rifle problem. The simple solution is to find better ammo.

 

[gotigers]

TULA is junk. I get to many failures with it. Use wolf or brass. The best steel case is the Hornady steel match.

 

[jsimmons]

IMHO rem oil sucks for the bolt carrier rails. Try something a little heavier.

I use synthetic wheel bearing greas on mine.

 

[jsimmons]

TULA is junk. I get to many failures with it. Use wolf or brass. The best steel case is the Hornady steel match.

What you probably meant to say is "Tula is junk in *my* rifle."

I have two ARs (a S&W and a home-made) and Tula works fine in both of them.

 

[greyling22]

gotigers, you know tula and wolf are the same thing right? well, depending on which line of wolf. the military classic is made by ulyanovk or something like that.

 

[Stack]

Feed ramps have nothing to do with a short stroke, but the PSA upper has them. It sounds to me like it is an ammo problem, not a rifle problem. The simple solution is to find better ammo.

You're right, feed ramps don't have a thing to do with a short stroke however they do effect feed reliability. A lot of people run Tula and find it reliable and cheap. If I build an AR that wont feed Tula I can easily remedy the situation. I don't use it but it really doesn't take a rocket scientist to tune an AR to function properly and that means even with Tula should you choose.

 

[TwoEyedJack]

As long as they don't hit the front of the mag you're OK. No factory rounds should be an issue in that regard.

It does sound like it's short stroking. Have you tried any other ammo? How does it run with quality fodder?

Runs great with Federal 55 gr. FMJ and 62 gr. FMJ. Also, all my brass cased loads run without a bobble including some that are on the other side of warm.

 

[TwoEyedJack]

Full auto bolt carrier? H2 or H3 Buffer? What buffer spring are you running? IMHO rem oil sucks for the bolt carrier rails. Try something a little heavier. Of course that probably wont have any effect on the short stroke problem. What do your feed ramps look like? M4 extended? Rifle or carbine stock? The whole thing has to work together.

I'm not exactly sure which buffer spring and buffer weight I have. This lower is from Bushmaster and started life with a 24" bushmaster A2 upper. It has standard feed ramps AFAIK. I tried the rem oil since that is what was in the truck. It was pretty cold that day, so I would think heavier oil would make the problem worse if it is short stroking.

 

[TwoEyedJack]

Ditch-Tiger nailed it. I ran 20 rounds through the pmag without a hitch! Problem solved.

 

[Stack]

Very nice. I run PRI and PMags but I'm switching out all the PMags eventually. It's taking some time at $40.00 per mag.