Since BCM doesn’t offer a 12.5 LW I was thinking of buying a 14.5 with carbine gas system; sending it off to Rainier Arms to have a gas block pinned and while it was there, having the barrel chopped to 12.5 and threaded. Would the gas port need to be enlarged for it to run unsuppressed?
My hope is that the gas port would still be large enough for the weapon to run reliably unsuppressed with a C or H buffer as this would be a really sweet shooting setup both suppressed and unsuppressed.
Won’t matter if you’re running unsuppressed. You’ll be able to compensate easily most of the time with buffer/springs. Just have Rainier check it - they can fix if it is funky before assembly.
If the 14.5" barrel is reliable, cutting it down and not changing the gas port should make it less reliable.
It might run but the concept of a smaller port being good for suppressed and unsuppressed is flawed. If it really was reliable with less gas all guns would be made than way, less recoil and wear on the rifle.
The Gov profile is LW under the handguards, for a few oz forward of the FSB you pay for the cut/thread and may loose reliability in adverse conditions. Also LW barrels have a step up at the muzzle for enough shoulder for the flash hider to seat against, if you cut down a LW barrel you may need a flash hider that stops on the muzzle (and longer threads to allow it).
Thanks Todd. I reckon I’ll pass on cutting it then.
First, I would double check the thickness of a LW barrel before cutting it (as it might be to small to thread).
The GP size would be fine for running suppressed, but there is a good chance that the bolt won’t lock back on the last round when not suppressed.
C4
Rainier should be able to estimate opening up the port IF needed on inspection.
Doh, good point on the step - most LW have no taper so they’ll never work BUT why not a standard M4 since you’re going to remove most of the heavy front end anyway and stop just close enough to leave a shoulder before the cut out. You’d have plenty to thread as well. I am sure a this has been tried many times before by people here. If you were totally obsessed with saving a fraction of an ounce you could turn down that inch in front of the gas block, too. Seems like a butt load of work though.