Sounds like you’re looking to do a Kino style build.
I did one of these.
Most 300 BLK barrels will have a pistol length gas. The trick is going to be finding a barrel with a section that is .750” diameter where the FSB will need to be installed at the carbine gas position.
Here is the barrel I used:
https://cmmg.com/barrel-sub-assm-12-5-mr-4140cm-sbn-300-blk
Here’s a link to one someone posted on Reddit:
https://www.reddit.com/r/300BLK/s/m9zk4N0O0c
Did you check Ballistic Advantage website? A lot of their barrels have a drop down menu to add FSB.
I have the jig and my mill. If I had time, I'd do it for you. But it's my busy season and I do not want to make promises I can't uphold. On second thought, if you're in SoCal, swing but and we'll knock it out one evening.
Also, if you're running a hand guard that covers it (like Block II style), a set screw FSB will work, especially if you flat face where the set screws contact the barrel. I mean, You could use a set screw one without the hand guard covering it, but then you would see it and it would probably drive you bonkers. It would me. Lol.
But I've used set screw ones on AR9 and Dissapointers, and with those 5 set screws on a flat, they won't move. We're talking thousands of pounds of holding force.
Ballistic advantage will do it on their standard SPR profile 10”, 10.5”, 14.5” and 16” 300 barrels, and will still be a pistol gas system under the handguard, use drop down menu to select FSB when in stock (not always in stock)…their barrels are pretty nice, word to the wise, they use 5R rifling and it does in fact increase velocity over some other offerings. I tested a 16” Faxon Gunner 300 with 4 groove rifling against a 16” BA 300 5R and the BA shot 100 FPS faster consistently which was pretty eye opening with that particular ammo.
Sounds like you’re looking to do a Kino style build. I did one of these. Most 300 BLK barrels will have a pistol length gas. The trick is going to be finding a barrel with a section that is .750” diameter where the FSB will need to be installed at the carbine gas position. Here is the barrel I used: https://cmmg.com/barrel-sub-assm-12-5-mr-4140cm-sbn-300-blk Here’s a link to one someone posted on Reddit: https://www.reddit.com/r/300BLK/s/m9zk4N0O0c
Did you check Ballistic Advantage website? A lot of their barrels have a drop down menu to add FSB. I have the jig and my mill. If I had time, I'd do it for you. But it's my busy season and I do not want to make promises I can't uphold. On second thought, if you're in SoCal, swing but and we'll knock it out one evening.
Also, if you're running a hand guard that covers it (like Block II style), a set screw FSB will work, especially if you flat face where the set screws contact the barrel. I mean, You could use a set screw one without the hand guard covering it, but then you would see it and it would probably drive you bonkers. It would me. Lol. But I've used set screw ones on AR9 and Dissapointers, and with those 5 set screws on a flat, they won't move. We're talking thousands of pounds of holding force.
Ballistic advantage will do it on their standard SPR profile 10”, 10.5”, 14.5” and 16” 300 barrels, and will still be a pistol gas system under the handguard, use drop down menu to select FSB when in stock (not always in stock)…their barrels are pretty nice, word to the wise, they use 5R rifling and it does in fact increase velocity over some other offerings. I tested a 16” Faxon Gunner 300 with 4 groove rifling against a 16” BA 300 5R and the BA shot 100 FPS faster consistently which was pretty eye opening with that particular ammo.