Ejection

**mullet eater** · 03-12-18, 18:43

Hey! I’ve been lurking around for a while but have a question about ejection, I’ve searched and can’t really find what I’m looking for. I have an ar15 parts gun that ran perfect with a semi auto bcg and standered buffer ejection was between 3 and 4 o’clock, I wanted to increase reliability and dependability so I installed a bcm bcg and now it looks like ejection is at the 2oclock range but I have brass marks on my casing deflector so I’m not sure what’s going on if the casing is bouncing off or what

So my question is to make the gun operate properly do I need a heavier or lighter buffer...

Thanks David

**markm** · 03-12-18, 18:58

Sounds like it's running just fine. BCM bolt probably has the proper ejecter spring tension, and thus pops the brass out more assertively.

**MegademiC** · 03-12-18, 22:07

Sounds like it is running properly. Ejection pattern can help diagnose an issue if you have one, but in and of itself is meaningless IME.

**countryboy27012** · 03-12-18, 22:12

If it will lock the bolt back on the last round, it's probably good to go. As stated before the BCM ejector spring is probably stiffer causing a different ejection path.

**Iraqgunz** · 03-13-18, 04:18

Man, it would be really helpful if we could get some more information about the rest of it.

Originally Posted by mullet eater

Hey! I’ve been lurking around for a while but have a question about ejection, I’ve searched and can’t really find what I’m looking for. I have an ar15 parts gun that ran perfect with a semi auto bcg and standered buffer ejection was between 3 and 4 o’clock, I wanted to increase reliability and dependability so I installed a bcm bcg and now it looks like ejection is at the 2oclock range but I have brass marks on my casing deflector so I’m not sure what’s going on if the casing is bouncing off or what

So my question is to make the gun operate properly do I need a heavier or lighter buffer...

Thanks David

**mullet eater** · 03-13-18, 18:30

Thanks for the help guys, sorry I didn’t really give much info on the rifle itself... it’s a 14.5 nitride coated barrel with pinned comp, yankee hill upper, BCM bcg, lower reciver is a Anderson arms with alg act single stage. The buffer and tube are a no name brand standard carbine buffer.

I did email Bravo Company today and they said all of there 14.5 uppers with the auto bcg use H buffer which I think would be a step up from what I have and it would calm down my rowdy gun lol but I’m still interested in what you guys have to say. If I left any info about the gun out let me know.

**bamashooter** · 03-13-18, 19:18

Originally Posted by mullet eater

Thanks for the help guys, sorry I didn’t really give much info on the rifle itself... it’s a 14.5 nitride coated barrel with pinned comp, yankee hill upper, BCM bcg, lower reciver is a Anderson arms with alg act single stage. The buffer and tube are a no name brand standard carbine buffer.

I did email Bravo Company today and they said all of there 14.5 uppers with the auto bcg use H buffer which I think would be a step up from what I have and it would calm down my rowdy gun lol but I’m still interested in what you guys have to say. If I left any info about the gun out let me know.

What kind of "rowdiness" are you experiencing with a 14.5" barrel? This is a .223 / 5.56?

**mullet eater** · 03-13-18, 20:06

Originally Posted by bamashooter

What kind of "rowdiness" are you experiencing with a 14.5" barrel? This is a .223 / 5.56?

The gun is real snappy, imo excessive recoil I guess with my old bcg it was real smooth.

**26 Inf** · 03-13-18, 20:48

Originally Posted by mullet eater

The gun is real snappy, imo excessive recoil I guess with my old bcg it was real smooth.

Are you shooting the same ammo?

Here is what I'm thinking with some questions thrown in: You say you replaced the SA BCG with a BCM BCG to increase reliability, not saying that isn't a good move, but just wondered, had you been having problems with the SA carrier?

The 'auto' bolt carrier should be heavier than the SA bolt carrier. I don't know exactly how much because there are variations between manufacturers, but I'd guess anywhere from .25 to 1 oz from what I've read.

So I'm thinking replacing that SA carrier with a BCM BCG added some weight which should have slowed things down a bit, thus moving your ejection pattern a bit towards the 5:00 from where it had been. Instead it did the opposite. Taking that into consideration, moving the ejection pattern from 4:00 to 2:00 would seem to indicate you are getting more gas to operate the system.

If BCG's were the only thing you swapped it would seem the BCM BCG is a much more effective piston than the old SA BCG/ Could be a number of things with your old BCG - gas key leaking a little, worn gas rings, etc.

One way to fix this, and soften recoil, is to add buffer weight, as BCM already told you. A carbine buffer weighs around 3 oz, an H weighs around 3.8 oz, the H would probably do you fine. If it was me, and I had the money, I'd buy an H and an H2 (the H2 weighs about 4.7 oz) and see if it ran reliably with the H2 for the softest recoil.

You should also measure your buffer spring, it should be between 10 and 10.5 inches long, if it is shorter than 10 inches replace.

JMO