Suppressor optimized gas port?

[usbp379]

Has anyone here played with cutting a 14.5" or 16" barrel down to ten or eleven inches for suppressor use?

If so, did you leave the gas port alone or drill it? What ammo and suppressor are you running?

On a related note, who else other than Sionics is making a dedicated short barrel for use with a can?

[gatordev]

Has anyone here played with cutting a 14.5" or 16" barrel down to ten or eleven inches for suppressor use?

If so, did you leave the gas port alone or drill it? What ammo and suppressor are you running?

On a related note, who else other than Sionics is making a dedicated short barrel for use with a can?

I've had two 16" (Colt) barrels cut down to 10.3 by ADCO and both run like sewing machines with and without suppressors. ADCO has the spec on what to drill the port to. It's public knowledge (it's whatever the MILSPEC is), I just can't remember off the top of my head. I also run a Centurion Arms 12.5" that's been problem free in both configs, as well. BCM seems to be configured correctly, as well.

For a "dedicated short barrel for use with a can," I'll defer to others. Personally I like the ability to run in both modes (without blowing the gun out and/or causing malfunctions), so that's been my focus.

[usbp379]

Sionics currently makes an 11.5" barrel that's got a small-ish gas port. That barrel is supposed to be spec'ed to work best with a can attached.

"Work" is a somewhat relative term here too. If we can come up with a gas port that'll allow the rifle to feed and eject but maybe not lock the bolt back without a suppressor that might be preferable to a gun that runs violently and blows excess gas all over the place like some SBR's do once the can is screwed on.

[Former11B]

Has anyone here played with cutting a 14.5" or 16" barrel down to ten or eleven inches for suppressor use?

If so, did you leave the gas port alone or drill it? What ammo and suppressor are you running?

On a related note, who else other than Sionics is making a dedicated short barrel for use with a can?

I cut a 16" FN barrel down to 10.5" and I run it suppressed with no adjustment to the gas block. I've got the factory fixed front sight post (carbine length gas and I believe the port size is .071" with a .750" gas block seat) and the only gas mitigation I have on that rifle is RTV silicon in the charging handle. The rifle itself could probably use a heavy buffer to reduce carrier speed a little but I don't get gas in the face.

[gatordev]

I believe the Crane spec for a 10.3" barrel is .071" with a H2 buffer. I don't know what the spec is for a 11.5", but I'm guessing it's exactly what BCM uses, since they tend to run without issues.

[mtdawg169]

I believe the Crane spec for a 10.3" barrel is .071" with a H2 buffer. I don't know what the spec is for a 11.5", but I'm guessing it's exactly what BCM uses, since they tend to run without issues.

I beleive that the 11.5 BCM is ported a little bigger than that, maybe 0.076. The Sionics reduced gas port barrel is right at 0.070 of I recall correctly.

[voodoo_man]

Buy a Gemtech 556 SBC and you don't have any problems regardless of length...

[gatordev]

Buy a Gemtech 556 SBC and you don't have any problems regardless of length...

According to my fans, I haven't had any problems with length without the SBC. Maybe it's just you.

[Former11B]

According to my fans, I haven't had any problems with length without the SBC. Maybe it's just you.

I see what you did there

[mtdawg169]

Buy a Gemtech 556 SBC and you don't have any problems regardless of length...

I know a lot of guys are using the gemtech carrier with good results and are happy with it. But I just can't get behind it. Having to remove it to gain access to the switch isn't ideal to me. And at the same time, I've never really been happy with the idea of restricting gas flow at the carrier. Same goes for adjustable gas keys.

I ultimately went a different route, via the Sionics reduced gas port barrel, LMT enhanced carrier and Vltor A5 buffer system.

[Slippers]

I know a lot of guys are using the gemtech carrier with good results and are happy with it. But I just can't get behind it. Having to remove it to gain access to the switch isn't ideal to me. And at the same time, I've never really been happy with the idea of restricting gas flow at the carrier. Same goes for adjustable gas keys.

I ultimately went a different route, via the Sionics reduced gas port barrel, LMT enhanced carrier and Vltor A5 buffer system.

The Gemtech SBC isn't like an adjustable gas key because it vents excess gas directly out the side of the carrier. This is somewhat similar to what the LMT enhanced carrier does, but on a greater scale when set to suppressed.

Voodoo has recommended the SBC since the beginning of the year, and I finally switched over to one a couple months ago when I got my LMT MRP 10.5. Having to remove the carrier to change the setting has yet to bother me because it's basically tool-less (just use the rim of a casing), and I shoot 99% suppressed. It makes for a very pleasant suppressed shooting experience, so I now have an LMT enhanced carrier sitting lonely in the parts box.

Also, you can access the toggle without completely removing the carrier from the upper. It's not too involved to shotgun the receivers apart, pull the bolt back without touching the charging handle so the carrier can't fall out, and change the setting.

If I had the ability to use an adjustable gas block, I probably would, but it's not an option with the LMT monolithic receiver platform.

[mtdawg169]

The Gemtech SBC isn't like an adjustable gas key because it vents excess gas directly out the side of the carrier. This is somewhat similar to what the LMT enhanced carrier does, but on a greater scale when set to suppressed.

Voodoo has recommended the SBC since the beginning of the year, and I finally switched over to one a couple months ago when I got my LMT MRP 10.5. Having to remove the carrier to change the setting has yet to bother me because it's basically tool-less (just use the rim of a casing), and I shoot 99% suppressed. It makes for a very pleasant suppressed shooting experience, so I now have an LMT enhanced carrier sitting lonely in the parts box.

Also, you can access the toggle without completely removing the carrier from the upper. It's not too involved to shotgun the receivers apart, pull the bolt back without touching the charging handle so the carrier can't fall out, and change the setting.

If I had the ability to use an adjustable gas block, I probably would, but it's not an option with the LMT monolithic receiver platform.

10-4. Part of my goal with that build was a tooless gun that was set up to run well suppressed, but require no changes when the suppressor comes off. Granted, that's not often though. I've pretty much set all my guns up the same way now, with the enhanced carrier and A5. I could obviously get even more gas reduction with an AGB or the gemtech carrier. But I just can't get past my hang up with needing to have tools available or fooling with the switch. But that's just me being anal.

[usbp379]

That's kind of my idea. Build a gun that's supposed to be suppressed most of the time. The only time the can comes off is when the gun needs cleaned or just to break the carbon loose.

With regard to the SBC; does the "selector switch" get fouled or jammed with extended use? That's one of the complaints I've seen with most everything that restricts gas flow.

[alamo5000]

The Gemtech SBC isn't like an adjustable gas key because it vents excess gas directly out the side of the carrier. This is somewhat similar to what the LMT enhanced carrier does, but on a greater scale when set to suppressed.

Voodoo has recommended the SBC since the beginning of the year, and I finally switched over to one a couple months ago when I got my LMT MRP 10.5. Having to remove the carrier to change the setting has yet to bother me because it's basically tool-less (just use the rim of a casing), and I shoot 99% suppressed. It makes for a very pleasant suppressed shooting experience, so I now have an LMT enhanced carrier sitting lonely in the parts box.

Also, you can access the toggle without completely removing the carrier from the upper. It's not too involved to shotgun the receivers apart, pull the bolt back without touching the charging handle so the carrier can't fall out, and change the setting.

If I had the ability to use an adjustable gas block, I probably would, but it's not an option with the LMT monolithic receiver platform.

I've always wondered about over doing it or if it would be worth it... I am running an adjustable block, a heavy buffer, a extra power spring, and a griffin snach as is... the buffer and the spring did miracles to make my SBR run smooth as ice.

If I toss in a Gemtec bolt I'm almost scared that it will screw up what I've accomplished so far! LOL

[Slippers]

If you have an adjustable gas block there's no real need for the SBC.

Fouling: hasn't happened yet. Voodoo might be able to tell you. I believe he ran a multi day course and got to 800 rounds with a suppressor and SBC before it started to slow down from fouling. I'm curious about the selector after that, as well.