BRT or BCM now or wait for Geissele?

[titsonritz]

The BCM will only be overgassed at best

My BCM 14.5" mid-length gas port pin gaged at .076", does not seem over-gassed to me. What size port should they use?

[17K]

My BCM 14.5" mid-length gas port pin gaged at .076", does seemed over-gassed to me. What size port should they use?

.076” is fine on a 14.5” mid but there’s something going on with their barrels that make them cycle hard.

[HCrum87hc]

I’d go BRT all day every day over the other two. The BCM will only be overgassed at best and Geissele has no clue what they’re doing with their standalone barrels. No. Clue.

This is the correct answer. BRT is the best option. BCM is good, but I agree will be overgassed. G should stick to triggers and rails.

[kwelz]

Looks like BRT is the winner. I already have one of their 12.5 and love it. For that matter I also have an 11.5 Geissele. I am just pretty out of the loop lately on how quality has been, so I figured it was better to ask around than waste money and time on something I will end up having to fight with.

[1168]

.076” is fine on a 14.5” mid but there’s something going on with their barrels that make them cycle hard.

Was yours an ELW?

[crowkiller]

First world problems here.

I just picked up a Radian Builders kit and have everything to finish it except the barrel.

I want to keep this build fairly light so I am looking at either a BCM ELW barrel or a Black River Tactical 16". I know both are great barrels. However the other option would be to wait for Geissele to get more in stock.

Any real Pros or cons on any of these choices that you all can think of that I may be missing?

This will actually be my only 16 inch AR. It will have a Tango6T on top but most of my shooting is within a couple hundred Yards.

Have you considered Centurion Arms?

[17K]

Was yours an ELW?

I had a pair of ELW uppers I bought from them in ‘17 that cycled so hard they mangled the BCM and Colt firing pin retaining pins, and tore up rims on cases.

Since then I’ve been around quite a few BCM guns at work and I’ve made a pretty serious effort to shoot them side by side with whatever 6920s I have on the line and they invariably kick harder. Especially with heavy A5 garbage behind them. But most midlengths do.

[1168]

I had a pair of ELW uppers I bought from them in ‘17 that cycled so hard they mangled the BCM and Colt firing pin retaining pins, and tore up rims on cases.

Since then I’ve been around quite a few BCM guns at work and I’ve made a pretty serious effort to shoot them side by side with whatever 6920s I have on the line and they invariably kick harder. Especially with heavy A5 garbage behind them. But most midlengths do.

I usually get told I’m an idiot when I post this, but a gas port diameter that works well on a .750 journal might not work as well on a .650 journal, because the length of a tube affects flow at any given pressure.

[georgeib]

I usually get told I’m an idiot when I post this, but a gas port diameter that works well on a .750 journal might not work as well on a .650 journal, because the length of a tube affects flow at any given pressure.

I don't know who's calling you an idiot, but you're absolutely correct. You would need to go down one port size from a .750 to a .625 journal.

I think Clint was the one who gave the example of blowing through a long straw, and then cutting that straw in half and blowing again. It immediately becomes obvious how much less resistance there is with the shorter straw.

[17K]

I usually get told I’m an idiot when I post this, but a gas port diameter that works well on a .750 journal might not work as well on a .650 journal, because the length of a tube affects flow at any given pressure.

Colt agrees. They do .071” on their .625” journal 16” mids.