New .300 Blackout Shell Ejection Questions

[Squaregrouper]

I took my new .300BO 8.5" PSA upper out today. I put it on to a new lower and an existing buffer tube w/Sig Brace. The buffer assy. functioned flawlessly on a 5.56 pistol that is now a SBR.
Anyway, I have a few questions and a problem:
1- I fired one 30rd mag and noticed significant "brass dust" on the face of the shell deflector, especially for only shooting 30rds. When I collected my brass, I noticed the case neck's tips were all bent inward. I believe the brass was hitting the shell deflector with enough force to damage the brass.
All brass was landing around 5:00, ~6' away. I have never had this issue with 5.56 AR's. Should I get a heavier buffer or spring to solve the "problem"?
2- After the last round, the BCG locked back and the CH was flopping around. I was able to (safely) drive the barrel tip into the bench and the BCG released and appears normal. I took it down and found nothing out of the ordinary.

I figured I should stop shooting and start asking questions. Google ain't cutting it and MDS tends to provide good answers/solutions.

 

[Klunatic]

Its completely normal. When you reload the necks will resize just fine. The larger diameter neck I think accounts for the dents in the neck. Are your running a Tubbs Flat wire spring in the lower? If not that will cure most of the noise and any other BC problems in the .300blk. Not sure why the carrier handle would be flopping around, can you describe it more detail?

 

[Squaregrouper]

Its completely normal. When you reload the necks will resize just fine. The larger diameter neck I think accounts for the dents in the neck. Are your running a Tubbs Flat wire spring in the lower? If not that will cure most of the noise and any other BC problems in the .300blk. Not sure why the carrier handle would be flopping around, can you describe it more detail?

Only after the last round was fired. The bolt locked "too far back" and I couldn't get it to move forward. At the same time, the CH was acting like it was in the upper sans a BCG- just rattling around.
I remembered the military emergency method of smacking the barrel's bore tip on the ground (2x6 for me) to release the bolt. It worked, but I felt there was a problem and ended my shooting session.
Upon disassembly, I was expecting something funky with the buffer retainer pin and spring, but they were fine.

I don't remember who made the retainer spring, other than the buffer was a slightly larger OD designed specifically to fit tightly on a Sig Brace. The buffer tube, spring and buffer came as a kit. I fired >500rds in 5.56/.223 with no problems in a 10.5" carbine gas system.

EDIT- I now have a pistol gas system. Should have thought of/posted this info earlier.

 

[Sticky]

It is perfectly normal for the empty shells to deflect off the deflector (that's what it's there for!). They will leave brass residue and slightly dent the necks. No biggie. If you don't like it, just take a piece of fuzzy side velcro (or stickyback felt) and stick it on the deflector surface.. no more brass marks and it will minimize neck dents too..

You should probably check to see if the bolt carrier is being driven all the way back against the lower receiver... separate the upper and lower, remove the buffer itself from the buffer tube, put a small dab of grease on the rear (bumper pad) of the buffer and reinstall it carefully as to not smear the grease on the pad. Take your BCG and by hand, insert it into the buffer tube, depress it allllll the way down til it won't go any further. Check to see that it isn't making contact with the lower receiver in the buffer threaded section of the lower (smacking into the lower with the gas key, or any other area of the bcg. It should be bottoming out about 1/8" or so before the gas key strikes the lower receiver. Now remove the buffer again and see if the dab of grease on the buffer pad was smeared against the back of the buffer tube when you bottomed the bcg out. The pad should bottom out in the buffer tube when the spring is fully compressed by the buffer driving rearward. If it's not, the spring may be loading up and not to spec, or in some cases, the pad on the buffer won't bottom out before the bcg makes contact with the rear of the lower receiver. This can be remedied with shims (or quarters in a pinch) to 'shim' the back of the buffer tube a bit. Just remove the buffer and buffer spring and add a quarter or two at a time, put it back together and retest it to ensure the bcg isn't traveling too far rearward..

 

[John from MD]

+1 on the velcro, it really does stop dents. As far as your BCG getting stuck, I would check to see if your BCG retainer is out of spec or damaged and is getting jammed. This could be caused by screwing in the butt stock tube too much.

 

[teratos]

Thanks for the velcro tip! Genius!

 

[Squaregrouper]

It is perfectly normal for the empty shells to deflect off the deflector (that's what it's there for!). They will leave brass residue and slightly dent the necks. No biggie. If you don't like it, just take a piece of fuzzy side velcro (or stickyback felt) and stick it on the deflector surface.. no more brass marks and it will minimize neck dents too..

You should probably check to see if the bolt carrier is being driven all the way back against the lower receiver... separate the upper and lower, remove the buffer itself from the buffer tube, put a small dab of grease on the rear (bumper pad) of the buffer and reinstall it carefully as to not smear the grease on the pad. Take your BCG and by hand, insert it into the buffer tube, depress it allllll the way down til it won't go any further. Check to see that it isn't making contact with the lower receiver in the buffer threaded section of the lower (smacking into the lower with the gas key, or any other area of the bcg. It should be bottoming out about 1/8" or so before the gas key strikes the lower receiver. Now remove the buffer again and see if the dab of grease on the buffer pad was smeared against the back of the buffer tube when you bottomed the bcg out. The pad should bottom out in the buffer tube when the spring is fully compressed by the buffer driving rearward. If it's not, the spring may be loading up and not to spec, or in some cases, the pad on the buffer won't bottom out before the bcg makes contact with the rear of the lower receiver. This can be remedied with shims (or quarters in a pinch) to 'shim' the back of the buffer tube a bit. Just remove the buffer and buffer spring and add a quarter or two at a time, put it back together and retest it to ensure the bcg isn't traveling too far rearward..

Backwoods brilliance at its finest.

 

[Squaregrouper]

+1 on the velcro, it really does stop dents. As far as your BCG getting stuck, I would check to see if your BCG retainer is out of spec or damaged and is getting jammed. This could be caused by screwing in the butt stock tube too much.

Does this have another name? I don't know what a BCG retainer is.

 

[John from MD]

My mistake, we were talking about BCG's and my brain locked on it. I meant the buffer retainer. It is the spring loaded piece in the threaded portion of the lower receiver.

Sorry,

 

[outrider58]

If you are saying the charging hand had play in it when you drew it rearward on a locked back bolt, all CHs do that to some extent. It's normal because, with the bolt locked back, there is no load on the charging handle. I would also inspect your bolt catch. That may be damaged as well causing the bolt to lock further back than what is required.

 

[Squaregrouper]

I checked/tested every previous post and everything seems fine.
I will head to Michael's and get some velcro while I'm at Hong Kong freight getting a cut off saw for converting 5.56 brass.

 

[John from MD]

Make sure you clean the brass deflector with alcohol before applying the velcro. Also, the fuzzy part works better than the plastic loop part.

 

[bigjohn]

I put black rtv silicone on the brass deflector instead of the Velcro. Little more permanent. It works the same.

 

[outrider58]

I like the patina.

 

[teratos]

I like the patina.

This. Not that any of my guns are beat up, but I'm not worried about scratches on my tools.