10.5 req heavy buffer or adj gas block, decrease in velo use otmbab - FN America Ar15 Barrel 10.5inch Bb M16 5.56 Carbine

The 10.5 inch barrel for so many such a beloved barrel size its basically the shortest length you can go and still run a carbine length gas system, which is why in mid 2000s Socom decided to use it. 16 inch barrel can get in the way, adding a surpressor to a 14.5 inch barrel is too long for cqb and not easily riden around in 4 runners, humV. Just about every 10.5 inch barrel ive shot was gasy Reason the gas hole is slightly enlarged possibly .125 or the same diameter as the tube. Ehy did they do this couole reasons. The first is so thst ut can run full auto with a surpressor. If you had a tiny little gas hole you can bet theres gonna be too much back pressure gas tube is gonna over heat the barrel then over heats as well, gun stops working when that happens in my experience. Ive seen someone run a pistol length gas system on a 16 in barrel. It worked in semi but in binary it over heated quickly you need more dwell time you need a slightly bigger gas hole as well like on the 10.5 mark 18. The other reason is so they can run any ammo and chew through it. Doesn't matter if its under powered ammo it will fire and cycle. My first 10.5 inch barrel I immediately just put in a standard spring and buffer and it ejected at 2oclock and i felt more kick then i normally do. So i decided to get the Geissele super 42 spring with the H2 buffer and then it ejected at 3. The braided spring and heavier buffer slowed down the bolt just enough for it to flick that shell out exactly where i wanted it. Every time with regular m193 ammo. I tried some m855 pretty much same results. Then i started to get speedy with a wide open trigger and to my surprise not one issue. I put in an Aero Spring. The issue with the Geissele Springs from my understanding is that. You might get stove piping because the spring is sending the bolt home way too fast so as the bolt ejects a round its already begun to come back and the new round and ejected shell hit each other. But if you run an H2 buffer with a regular spring not one of those cheap silver trash springs 10.5 and decent ammo run well. chrome lining keeps the barrel from rust. I adjust my gas block i just fire one round at a time with the threads almost closed until it stays open. Thats the sweet spot that the best dampening. 10.5 in 300 black out needs heavy buffer but too heavy and you can't shoot subsonic, Reverse magnetic buffer great for dampening but action may not get thrown open weight of the buffer being thrown past the bolt catch is how last rd stays open. With magnetic you can be light enough for subs stiff enough for supers find the perfect dampening but you have to just hear click on the last round. Or you separate the magnets more but your shot suffers. It fires with the same amount of Jules as an AK-47 and when using an sbr your not going to have the greatest control. Ive tried everything magnetic buffers too, reverse magnetics no buffer bounce but not enough weight to constantly keep the action open each time. So there 3 ways to deal with over gasing or dampening a round to be able to cycle well and have the best accuracy and with the DI system you can adjust your gas block you can use reverse magnetic buffer which the magnets do not like to be close together this making it stiffer so when it hits the bottom of the buffer tube it absorbs the shock, a heavy buffer does the same thing extra weight so the buffer slows down that bcg and the super 42 braided spring makes it harder to compress. So does a reverse magnetic buffer. The super 42 spring returns the bolt with great power too fast damages the bolt ( best used with the 18 inch barrel)and the magnet has issues keeping the action open.(adjust you gas block instead) 10.5 plus 6 inch surpressors makes it the same length as the m4 thats why I believe the SF used the 10.5. ballistics show 12.5 is a better length. At 10.5 bullets velo isnt fast enough to do what they were designed and thats tumble and shrapnel apart. The 12.5 has just enough speed to begin to tumble and or shrapnel. Rem 223 was made to tumble out of a 20in barrel not the 10.5 so create more damage they can use a heavier bullet with open tip or steel core. It is recommended to use an H2 buffer. Remember to always use decent magazine springs part of a DI system relies on that spring to have the next round ready and if its old or weak it can seem like the gun has issues. The 10.5 inch barrel for many is a beloved barrel size its basically the shortest length you can go and still run a midlegth gas tube. Surpressor guys love it the most. If the hole is smaller then your used to they took account the length so it will probably shoot perfectly. Avoid cheap ammo.