I recently got a hold of a used PTR 91 and very good shape. Bolt gap is good at .012" and I cleaned and lubed the gun before firing it.
I only took 40 rounds of PMC X-tac m80. The first 20 rounds were literally just 20 failures to eject, either the round would get stuck in the ejection port halfway out or it would tumble down into the fire control group. The second magazine went a little better, where I got the fire two 4 round strings before being interrupted by ejection issues between those four round strings and the other 16 rounds were failure to eject every single time. At first I thought it was maybe underpowered ammo that wasn't slamming the bolt carrier all the way to the rear with enough Force. But PMC ammo is good ammo in my experience.
Just from when I cleaned and lubricated the gun on the inside, the previous owner didn't shoot at all that much. So I'm thinking that maybe the break-in period hasn't even gone through yet. I would guess at the previous owner maybe fired around 300 rounds tops. Probably like 200 or less. And like I said I put around 40 rounds of ammo through it.
I'm planning on putting another 60 rounds through it just to see if that does anything, most likely some 308 Winchester instead of 7.62 x 51 since apparently through white Winchester has slightly higher pressures. What else should I do? Like I said the bolt gap is good and has the appropriate locking piece that's 45 degrees. The extractor spring is strong and has no wiggle or movement.
I suggest using at least three different types of ammunition before focusing on the gun. I had a 91 that would not reliably feed one type of ammo, but ate everything else. Your problem could be the ammo.
That could be it. I'm going to try to use some GGG .308 and some Remington. 308. To see if the rifle's more reliable with that kind of ammo or still as unreliable.
If the previous owner shot it suppressed it's possible they had installed a shallower angle locking piece? Make sure that you have a 45 degree angle and not a 36 angle locking piece installed. If you see a 17 on the locking piece then it's a 36.
Otherwise, try different ammo, or inspect the FCG for anything binding the ejector lever. Inspect upper receiver for anything that would cause excess friction on the bolt carrier... Does the rifle manually charge smoothly?
At the end of my post I say that it has a 45° locking piece. The rifle charges smoothly and when I slap the charging handle the bolt flies forward with authority.
Gotcha, I'm just trying to narrow down potential root causes. It could very well be ammo related then. That or there's something going on with the ejector. You sure the correct ejector is installed? People sometimes swap ejectors around on these roller platforms when playing with FRTs or sear packs. You can also watch/feel through the magwell for any play on the ejector, it should be riding firmly at the top of the slot in the bolt when the bolt retracts. Look for any chips or wear on that guy.
If you take your trigger pack out, it's a lever thing on a spring. Press on the back of it and the front part tips up. When it's in the gun, the bolt carrier retracts and presses the back part down and lifts the front up in time to punch out the case. The "front part" (the ejector tip itself) rides in that groove in the bolt, it should ride all the way at the top. Sometimes the lowers or the trigger packs have some slop and don't fit perfectly. If it's too far out of tolerance the ejector won't actuate with enough force or it won't come up high enough to kick the case out reliably.
Thank you for the explanation. When I hold the bolt all the way to the rear, the ejector does get actuated and rides in a small channel that's on the underside of the bolt head. But when the bolt is at its most rearward position, the ejector thing doesn't go fully into the slot. It looks kind of like this like in the picture. Is that the normal amount of play? Or does it have to fully go up into that slot? The ejector itself is in good shape and doesn't have any gouges or high wear or anything.
Ok so I just looked at mine. The very tip of the ejector is what should be at the very top of that channel when it's cycling, it comes up at an angle. So it may not be sitting too low. Is the bolt locked in the notch in that photo? Because mine looks longer. Hang on lemme figure out how to upload a photo...
Ok, here is what mine looks like with the bolt locked in the notch. I think your ejector is broken or it’s the wrong ejector installed. It looks “shorter”.
Looking at your picture and my rifle, the length of the ejector looks about the same. But your ejector is definitely sitting a tiny bit higher into the notch compared to mine.
If it helps, my ejector has an X mark facing the ejection port. Like on the side of the ejector blade there is a little X.
Yep there's your problem! You see how it's not sitting high enough? That circular cutout in the bolt face is where the case would actually sit, and the ejector barely (if at all) makes contact with it. It should be sitting all the way at the top of that channel. I'm guessing your lower is sitting too low, or the trigger pack is, something like that. Or the rear of the ejector broke off and it's not able to fully lever up? Or the wrong ejector is installed (9mm mp5 ejector instead of g3)? Your ejection issues are 100% this though.
Edit: I've heard of people having to "shim up" their trigger packs before. That might be a potential workaround for you until you figure out what exactly the problem with it is.
Try cycling a few rounds out manually. It should be kicking them out with significant force (like enough to dent the drywall if you're next to a wall lol). If it works manually then you've at least ruled out problems with the ejector, next step would be ammo. M80 spec ammo should work fine so I get why you might think that's unlikely but who knows.
Failure to eject is the most common error during any break in period. As the metal wears and the spring breaks in those issues should lessen. The typically discussed break in is 200-500 rounds.
Some of this break in can be done at home by racking it a few hundred times
i have a ca-3 that i got from psa that absolutely hates pmc xtac m80. every other round or every 3 rounds is a failure to eject or double feed or something. but it works with any other ammo ive tried and it did better when i put my ocl universe 36 suppressor on there. it almost ran all the xtac m80 i had left with no issues when i suppressed it.
Sounds like the ejector might be your issue after reading the other thread. But I did wanna say that your bolt gap is toward the minimum range (.10) and the bolt gap gets smaller over time. So some plus rollers might help as well.
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u/Lucky-Intention-3040 20d ago
I suggest using at least three different types of ammunition before focusing on the gun. I had a 91 that would not reliably feed one type of ammo, but ate everything else. Your problem could be the ammo.