BCM Barrels Over Gassed

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[ARCHIVED THREAD] - BCM Barrels Over Gassed

Posted: 8/28/2014 10:26:19 PM EDT

Was talking with one of my local smiths who informed me that BCM barrels have larger than normal gas ports. Anybody have any experience to back it up?

Posted: 8/28/2014 10:32:01 PM EDT

[#1]

My 11.5 bcm barrel had a smaller than normal gas port.

ETA:

This was on a new BCM upper with carbine gas and LW barrel. It would correctly cycle unsuppressed about 10% of the time. Stovepipes and doublefeeds were what I got most of the time. It ran better suppressed, but still only 50%. Tried all the different buffers and springs and BCG's and it still wouldn't run. Checked the gas port and it measured .065". Opened the port to .080 and she runs 100% suppressed or not.

Posted: 8/28/2014 10:46:12 PM EDT

[#2]

My 11.5 needs a Tubb flat wire recoil spring and a Spikes H3 to run smooth, also must add a Tubb CWS to shoot suppressed.

Posted: 8/28/2014 11:03:05 PM EDT

[#3]

so that implies that it's over-gassed?

Posted: 8/28/2014 11:18:14 PM EDT

[#4]

My 11.5" BCM upper ejects at 4:30ish with lighter reloads(23.5gr H335, CCI #41, 55gr FMJ) using an H2 buffer and standard spring so I would say mine has a smaller port than say DD would.

Posted: 8/29/2014 12:49:02 AM EDT

[#5]

My 14.5 BCM mid will not cycle lower powered ammo like Tula with a carbine buffer.

UNDERgassed.

Posted: 8/29/2014 1:20:51 AM EDT

[#6]

I have a BCM 14.5 LW carbine, 14.5 M4 carbine, 11.5, and 16" midlength barrels and they all run 100% with the same lower having a standard buffer. 55's, 69's, 75's. They all work for me.

Posted: 8/29/2014 6:02:43 PM EDT

[#7]

BCM M4 carbine here. Shoots everything with an H buffer just fine. Thinking of moving up to an H2.

Posted: 8/29/2014 9:19:19 PM EDT

[#8]

My 11.5" (now 10.75") runs great on any quality ammo, both suppressed and unsuppressed.

Standard BCM carrier, standard spring, BCM H2 buffer.

Posted: 9/1/2014 1:11:53 AM EDT

[#9]

So what I'm seeing so far is that one's over gassed, two are over gassed, and three are just right. Sounds like Goldielocks found her way into barrels. Just received a BCM fluted lightweight 14.5 and looking to change over to a spikes 14.5 enhanced profile CHF for running suppressed. Even if BCM's are "just right" not sure the lightweight would be able to handle the increased pressure of an attached suppressor.

Posted: 9/1/2014 2:35:59 AM EDT

[#10]

My 16" BCM middy eats anything you can feed it supressed or not. H3 buffer and sprinting blue spring.

Posted: 9/1/2014 6:52:18 PM EDT

[#11]

Quote History

Quoted:
So what I'm seeing so far is that one's over gassed, two are over gassed, and three are just right. Sounds like Goldielocks found her way into barrels. Just received a BCM fluted lightweight 14.5 and looking to change over to a spikes 14.5 enhanced profile CHF for running suppressed. Even if BCM's are "just right" not sure the lightweight would be able to handle the increased pressure of an attached suppressor.

View Quote

I think you're over thinking it... Just run the BCM, I bet it'll be fine.

[ARCHIVED THREAD] - BCM Barrels Over Gassed

AR-15 » Rifles, Uppers, Lowers, Barrels, and more

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