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Steve in PA
08-07-12, 15:20
The rifle is a 16" BM, running an "H" buffer along with the BCM bolt upgrade. The rifle runs 100% with any ammo I care to feed it.

I did some video running a patrol rifle course and noticed something I can't say I ever noticed before; marks on the backside of the brass deflector. I would expect some on the front but I don't remember noticing the marks on the back. Thoughts?

http://i35.photobucket.com/albums/d159/Steve_in_PA/Misc/marks.jpg

This is a very short video of the rifle in action.

http://youtu.be/0yHiOlZJRbk
Meth0d
08-07-12, 15:30
My guess would be, as the ejected casing flies out, it is flipping and can hit the back of the deflector.
sinlessorrow
08-07-12, 16:02
Being a BM its probably overgassed.
davidjinks
08-07-12, 16:14
Did you happens to grab any of the spent brass after shooting? If so, did you notice any marks/swirls on it?

Are you the Steve in W-B Pa by any chance?



The rifle is a 16" BM, running an "H" buffer along with the BCM bolt upgrade. The rifle runs 100% with any ammo I care to feed it.

I did some video running a patrol rifle course and noticed something I can't say I ever noticed before; marks on the backside of the brass deflector. I would expect some on the front but I don't remember noticing the marks on the back. Thoughts?

http://i35.photobucket.com/albums/d159/Steve_in_PA/Misc/marks.jpg

This is a very short video of the rifle in action.

http://youtu.be/0yHiOlZJRbk
Steve in PA
08-07-12, 17:55
Did you happens to grab any of the spent brass after shooting? If so, did you notice any marks/swirls on it?

Are you the Steve in W-B Pa by any chance?

I have not noticed any marks on the brass.

And yes, this is me. Have we met?
Steve in PA
08-07-12, 17:58
Being a BM its probably overgassed.

Overgassed as too much gas pressure??

Bump up to a H2 or H3 buffer?
Eric D.
08-07-12, 20:24
My BCM 16" middy does the same thing running an H buffer. Non-issue IMO
Iraqgunz
08-07-12, 20:53
I would probably run an H2 with a BM carbine.
davidjinks
08-08-12, 09:13
I agree with IG. Switch your buffer out for an H2.

PM sent.

Edited to add: Are you using the O ring with the upgrade?



I have not noticed any marks on the brass.

And yes, this is me. Have we met?
davidjinks
08-08-12, 09:18
IG,

Is it possible that the extractor is holding onto the spent case too long upon extraction and isn't releasing it until the bolt starts to go home?

Basically hammering the rim of the case causing it to hit the back of the BD...



I would probably run an H2 with a BM carbine.
C4IGrant
08-08-12, 10:22
Overgassed as too much gas pressure??

Bump up to a H2 or H3 buffer?

H2 and a SpringCo Blue CS spring is what I would go with.


C4
brownfam
08-08-12, 11:27
How long have BM carbines been considered as "over gassed"?

Michael
C4IGrant
08-08-12, 11:41
How long have BM carbines been considered as "over gassed"?

Michael

Day 1 would be my guess.



C4
sinlessorrow
08-08-12, 12:07
How long have BM carbines been considered as "over gassed"?

Michael

Since day 1.

The issue is depending on where you hang out they are either overgassed and told like they are, or they are just as good as Colt and Mil-spec....
Steve in PA
08-08-12, 14:43
I agree with IG. Switch your buffer out for an H2.

PM sent.

Edited to add: Are you using the O ring with the upgrade?

I'll bump up to the H2 and see what happens. Yes, I'm running the O-ring that came with the kit.
sinlessorrow
08-08-12, 15:06
I'll bump up to the H2 and see what happens. Yes, I'm running the O-ring that came with the kit.

Take out the o-ring, its generally not needed and can cause issues
Steve in PA
08-08-12, 15:42
Take out the o-ring, its generally not needed and can cause issues

I had thought of that. I won't get my new buffer until next week, but this weekend I will run it minus the o-ring and see what happens.

Thanks.
davidjinks
08-08-12, 15:57
I have an H2 that's a spare. I'd more than happy to give it to you.



I had thought of that. I won't get my new buffer until next week, but this weekend I will run it minus the o-ring and see what happens.

Thanks.
FeltaDorce
08-08-12, 16:19
I tend to prefer my setups on the "over gassed" side of things. If the rifle operates with 100% reliability with all ammo types, I don't mess with it. I have increased the buffer weight on one of my S&W 15's, and now it is 5.56 only. It will short stroke .223 all day long. Each rifle seems to react slightly differently, but if you get 100% out of it, and the recoil and gas blowback is acceptable/normal 'don't fix what ain't broke.'
PA PATRIOT
08-08-12, 18:02
I also used a "O" ring with my older Bushmaster in the past and seen the same markings on the side and rear of the deflector. Once I removed it and installed a Wolff extra power extractor spring with black insert the strange markings on the deflector stopped

Just a side note I had damaged the front sight on my Bushmaster M-4 upper which was said to be from a canceled military contract after Colt sued Bushmaster over a patent infringement dispute. Any how while the front sight was off and I cleaned the carbon out of the port the gas port was measured by a friend who does precision machining and the port measured out at .0627 if I remember correctly.

I have to look it up but does this rounded up measurement of .063 fall within normal spec?

So far this rifle has 19,000rds fired and has been excellent with my favorite training load of Wolf 55gr Copper H/P's and handles 5.56 without issue using a "H: buffer and standard Mil-Spec spring which is changed out every 3500rds.

.