PSA AR9 BCG Key screw issue

[Troublesbrewin]

I was at the AGC today, and after running about 50 rounds through my AR9 the bolt key socket head cap screw broke and of course the gun would not cycle anymore. When I got home and disassembled the upper from the lower - pulled the BCG and saw the broken cap screw. I was a little surprised that there was only one screw holding the key in place, but now I need to extract the screw from the bolt without buggering the bolt threads. I have small screw extractors but what’s the best way to get a small bit to bite into that hardened screw without messing the bolt threads up?

 

[outrider58]

I was at the AGC today, and after running about 50 rounds through my AR9 the bolt key socket head cap screw broke and of course the gun would not cycle anymore. When I got home and disassembled the upper from the lower - pulled the BCG and saw the broken cap screw. I was a little surprised that there was only one screw holding the key in place, but now I need to extract the screw from the bolt without buggering the bolt threads. I have small screw extractors but what’s the best way to get a small bit to bite into that hardened screw without messing the bolt threads up?

Was the key screw a true grade 8 screw? I'd probably send it to PSA and have them deal with it.

 

[44man]

Was the key screw a true grade 8 screw? I'd probably send it to PSA and have them deal with it.

This right here

They will most likely send you another BCG

 

[Troublesbrewin]

I hadn’t even considered that outride58....I’ll give ‘em a ring tomorrow.
I don’t think I can drill that little screw without the bit walking all over the threads.

 

[RRomig]

I was at the AGC today, and after running about 50 rounds through my AR9 the bolt key socket head cap screw broke and of course the gun would not cycle anymore. When I got home and disassembled the upper from the lower - pulled the BCG and saw the broken cap screw. I was a little surprised that there was only one screw holding the key in place, but now I need to extract the screw from the bolt without buggering the bolt threads. I have small screw extractors but what’s the best way to get a small bit to bite into that hardened screw without messing the bolt threads up?

I had a problem with a bolt of theirs and they just sent a replacement.

 

[outrider58]

This right here

They will most likely send you another BCG

I had a problem with a bolt of theirs and they just sent a replacement.

Yup. They have piles of these things.

 

[Troublesbrewin]

Ya think that’s why their on gen 4 of their BCG?

 

[outrider58]

Ya think that’s why their on gen 4 of their BCG?

It's probably the screw(s). If they aren't grade 8 and the 'key' isn't properly mated and sealed to the BCG, it could happen again.

 

[4g64loser]

I've gotten key screws out of various bcgs before but it's not something I suggest trying without some tools at your disposal.

I flat the sheared surface with an endmill then touch it with a center drill so the actual bit won't walk. Once drilled all the way through to relieve it, I typically get the remnant of the screw hot with a small tip on the torch since a lot of idiots like to use thread locking compounds on these fasteners. If an extractor won't get it moving, step up in drill bits until an extractor will budge the remnant.

To OP: do what others have suggested and contact the MFG before attempting any extraction.

 

[Troublesbrewin]

I've gotten key screws out of various bcgs before but it's not something I suggest trying without some tools at your disposal.

I flat the sheared surface with an endmill then touch it with a center drill so the actual bit won't walk. Once drilled all the way through to relieve it, I typically get the remnant of the screw hot with a small tip on the torch since a lot of idiots like to use thread locking compounds on these fasteners. If an extractor won't get it moving, step up in drill bits until an extractor will budge the remnant.

To OP: do what others have suggested and contact the MFG before attempting any extraction.

It’ll be on it’s way to Palmetto tomorrow, unless they say “we’ll send you a new BCG”.

 

[4g64loser]

It’ll be on it’s way to Palmetto tomorrow, unless they say “we’ll send you a new BCG”.

Definitely for the best.

What I described is not something most people have the equipment to do. And there remains the element of risk even when done by a machinist.

 

[Troublesbrewin]

sent in a warranty request this morning, here’s a pretty good photo of the problem.

 

[4g64loser]

Chad will probably want to murder me for saying this, but I used to GTAW gas keys or charging handle abutments (9mm like this or the old colt SMGs) to carriers because this has happened before. The 223s would get loose due to bad staking or lousy screws. The 9mms liked to shear, as you have now seen.

 

[Troublesbrewin]

Do you know if the shear occurs due to the screw loosening, creating a gap which makes shearing more likely?

 

[outrider58]

Do you know if the shear occurs due to the screw loosening, creating a gap which makes shearing more likely?

It could be anything. If there is a gap or bow in the flat of the key, that might have a negative affect on the screws. Substandard screws can't handle the proper torque factor applied to them and can snap. Also, with an AR, you should always manually insert the bolt carrier into the buffer tube(while the buffer and spring are installed) and push it all the way in til it stops. You want there to be a small gap between the end of the gas key rear and the lower receiver extension. You never want the key slamming into the lower receiver extension. Bad things will happen.

 

[4g64loser]

Usually crap hardware.

 

[Troublesbrewin]

Just got an email from PSA warranty replacement BCG is in the mail!

 

[outrider58]

Just got an email from PSA warranty replacement BCG is in the mail!

Good deal.

 

[John from MD]

I was at the AGC today, and after running about 50 rounds through my AR9 the bolt key socket head cap screw broke and of course the gun would not cycle anymore. When I got home and disassembled the upper from the lower - pulled the BCG and saw the broken cap screw. I was a little surprised that there was only one screw holding the key in place, but now I need to extract the screw from the bolt without buggering the bolt threads. I have small screw extractors but what’s the best way to get a small bit to bite into that hardened screw without messing the bolt threads up?

I doubt it is hardened throughout.

 

[Troublesbrewin]

I got the new Gen4 BCG today, this one has two screws holding the key in place. Lubed it up with some synthetic motor oil and put ‘er back together. Better than new! Ready for pinging some steel.