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Discussion Starter · #1 ·
About once in 25-30 rounds the action will fail to go fully into battery and will lock up. (The gun is a Bula with a 19 in. match barrel.) I initially thought it might be a feeding problem and isolated to a single mag. But that is not the case. The gun functions well otherwise and I can shoot 2-inch groups over iron sights at 100 yds with the PMC (domestic loads) X-TAC 147 gr. Ball M80 7.62 NATO rounds.

When this happens, the action locks up. I clear the mag and have to free the bolt by either hitting the operating rod handle with a mallet or using the bench to engage the rod handle and applying force on the butt of the stock to open the action.

There is no indication of any obstruction on either the mags or the feed ramps to the chamber. I have not tried other ammunition.
 

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A lot of the time recommendations will to be to ensure the chamber is fully scrubbed clean. Then you need to question the headspace tolerances of the ammunition vs. the chamber. The M1A is supposed to have a 'tighter' match chamber. In a Bula build ask if their chambers are such as well? Do they give a measurement of the H.S.? I realize that if you are not the original owner you might not have all the info.
 

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Discussion Starter · #3 ·
A lot of the time recommendations will to be to ensure the chamber is fully scrubbed clean. Then you need to question the headspace tolerances of the ammunition vs. the chamber. The M1A is supposed to have a 'tighter' match chamber. In a Bula build ask if their chambers are such as well? Do they give a measurement of the H.S.? I realize that if you are not the original owner you might not have all the info.
I am the original owner. The gun only has about 200 rounds down the pipe. The chamber is clean, but I don't know about headspacing with this ammo. It is cheap range ammo. There could be some inconsistencies in the loads. I could try some Sierra Match loads to see if the problem repeats.
 

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I am the original owner. The gun only has about 200 rounds down the pipe. The chamber is clean, but I don't know about headspacing with this ammo. It is cheap range ammo. There could be some inconsistencies in the loads. I could try some Sierra Match loads to see if the problem repeats.
If you have a Sheridan gauge, drop those offending rounds into that gauge and I’ll bet they don’t drop all the way in.
 

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Discussion Starter · #6 ·
I don't have a Sheridan gauge, but it may be time to add one.
I don't have a Sheridan gauge, but it may be time to add one.
I don't have a Sheridan gauge, but it may be time to add one.
Thanks for the tip. Sounds reasonable and likely the next step. I wonder if anyone else has had similar issues with PMC 7.62 rounds -- these are from Texas and not Korea. My Mini 14 eats them with alacrity.
 

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Do you see a bunch of "rings" in the chamber from the chambering process? I own several Bula rifles and I had to polish the chamber on several of them made several years apart because the chamber was extremely rough. It was like the tooling was worn or whoever chambered the barrel just rammed the reamer in there really hard and fast and it didn't do a real clean job. There's a lot of guys on here smarter than myself that may chime in. For what it's worth I've shot thousands of those PMC rounds with no problems. Of course it's possible you have a bad lot or something.
 

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The PMC ammo is like military grade ball ammo that might function ok in a chamber that may be on the 'long' side as far as headspace goes. This allows for more reliable function with military ammo that could be sourced from many different manufacturers that are supposed to follow a certain spec. So if you get a minimally reamed/headspaced chamber, done so to tighten up tolerances for 'match' function you might get 'too long' ammo not cycling properly. So Kurt's test in Post#7 might work because the FGMM has more consistent match grade tolerance in its production.
 

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From personal experience, I think your rifles safety bridge may be restricting the firing pins return to resting thereby not allowing the bolt to unlock properly. A little deburing or replacement of the firing pin with USGI usually frees things up.
One test you can do to see if it is the firing pin, when it is locked up, remove the mag, point the muzzle directly up, tap the receiver and see if the op rod will now pull to the rear and eject the spent case.
 

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Discussion Starter · #11 ·
From personal experience, I think your rifles safety bridge may beIf restricting the firing pins return to resting thereby not allowing the bolt to unlock properly. A little deburing or replacement of the firing pin with USGI usually frees things up.
One test you can do to see if it is the firing pin, when it is locked up, remove the mag, point the muzzle directly up, tap the receiver and see if the op rod will now pull to the rear and eject the spent case.
When it locks up when close, but not totally in battery, a solid hit with a mallet on the op rod handle, does free it. I always remove the mag when this happens. I'll take a look. Thanks for the suggestion.
 

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How does the chamber look. Have you tried known good ammo like gmm. These things can sure be finicky, but once things smooth up , they are a joy and truly dependable.
 

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Discussion Starter · #14 ·
How does the chamber look. Have you tried known good ammo like gmm. These things can sure be finicky, but once things smooth up , they are a joy and truly dependable.
How does the chamber look. Have you tried known good ammo like gmm. These things can sure be finicky, but once things smooth up , they are a joy and truly dependable.
How does the chamber look. Have you tried known good ammo like gmm. These things can sure be finicky, but once things smooth up , they are a joy and truly dependable.
The chamber is clean and smooth. I use a chamber brush after each trip to the range.
 

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Factory PMC ammo is usually sized correctly for use in semi-autos. But ... try finger-chambering a box of them.
Push each cartridge firmly into the chamber with thumb pressure on the base of the case - no need to close the bolt. Then an easy flick with finger nail (or maybe small flat-blade screwdriver) should be enough to extract the cartridge. If any of the cases are wedged tight in the chamber then there's a problem with the ammo or the chamber.
 

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Discussion Starter · #20 ·
Thanks. I will check each round before loading into a mag. I no longer hand load. Even though I'm 80 years old, I still work about 60 hours a week. I try to get out to spend a day at the range a couple of days a month -- weather permitting. With limited spare time, I'm shooting factory loads and buying in bulk.
 
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