AR Sponsor
Posted: 7/2/2026 12:27:16 PM EDT
|
Been watching some YouTube videos on how the Sig Rattler (or similar) is the best 300 BO platform (ever). I kinda doubt it, but what y’all think? I will always shoot commercial subsonic with a suppressor. I will SBR this firearm. Not going to FRT this. I think I can get great performance by rolling my own upper, and I have no problem assembling my own upper. I’m leaning that way. I’ve read that barrel length is not that much of a concern with subsonic 300. Is that mostly correct? If so, which brand barrel you recommend for this? 5 or 6.5 inch 1:5 twist. Anything else recommended? Which gas block? Prefer a bit over gassed. |
Words fall from your mouth like shit from ass.
|
It was understood that load data was optimized for an 8 to 8.5" barrel. It was also a reloader's cartridge, because at the time, there were no or extremely few sources for the round. Noveske was the holy grail for barrels back then, with long lead times. I was lucky to find one on the EE. There are many sources for .300 barrels now, and several OEM sources for ammo. This rifle is stupid quiet with subs. It is funny how much attention a quiet rifle gets at the public range.  You can look through the holes and see the gas tube and fixed block. These parts came from Noveske, so no guesswork with gas. It runs subs and supers, can or no can.  |
Preferred pronoun: MARINE
|
Thanks. If I wanted to optimize for subs, is a shorter barrel just as good as a 8-8.5 inch barrel? I kinda want to use the suppressor back pressure to cycle as well. Optimized for subs and suppressor. Im thinking 4-6.5 inch barrel and an adjustable but a fixed is fine if it runs. |
Words fall from your mouth like shit from ass.
|
The Rattler is pretty unique and I think it's pretty decent quality wise along with the other MCX's.I haven't kept up with who does 1:5 but I think that will make your list pretty short. The Q Shorty barrel is 1:5 and even though it's spendy I'd certainly consider it. Seems like almost everyone settled on 1:7. No question an AR barrel is the cheapest way to get into it. |
BikerNut:
Normal people like motorcycles. Real people like motorcycles.
People who don't like motorcycles are just... weird.
Normal people like motorcycles. Real people like motorcycles.
People who don't like motorcycles are just... weird.
|
Originally Posted By Steamedliver: Thanks. If I wanted to optimize for subs, is a shorter barrel just as good as a 8-8.5 inch barrel? I kinda want to use the suppressor back pressure to cycle as well. Optimized for subs and suppressor. Im thinking 4-6.5 inch barrel and an adjustable but a fixed is fine if it runs. Shorter barrel setups can be more finnicky on gas but for a dedicated subsonic build just drill out a bigass gas port if it's not cycling  Originally Posted By ALASKANFIRE: The Rattler is pretty unique and I think it's pretty decent quality wise along with the other MCX's.I haven't kept up with who does 1:5 but I think that will make your list pretty short. The Q Shorty barrel is 1:5 and even though it's spendy I'd certainly consider it. Seems like almost everyone settled on 1:7. No question an AR barrel is the cheapest way to get into it. The gen1/2 rattler had a few differences from the rest of the MCX but the current gen3 / LT is compatible across all the gen3 line and a nice gun SLR and KAK both make 4-6" barrels with 1:5 twist, and KAK also sells 1:5 barrel blanks if you want to do something custom I don't exclusively run subs through these but they both have adjustable gas and can cycle them fine SLR 5"  KAK 7" custom 
|
|
Originally Posted By Steamedliver: Thanks. If I wanted to optimize for subs, is a shorter barrel just as good as a 8-8.5 inch barrel? I kinda want to use the suppressor back pressure to cycle as well. Optimized for subs and suppressor. Im thinking 4-6.5 inch barrel and an adjustable but a fixed is fine if it runs. KAK has some that short in 1:5. Faxon has a nice Match Gunner in 1:5, but it is a 7.5" (which is a very nice size). Edit - They make a 6" Gunner as well. 1:5 opens you up to a couple of heavy hitting subs (238gr and 242gr Makers), but might limit you on some popular jacketed supers (if Berry's subs) if you run a can. I'm a huge 300blk fanboi, and would never talk anyone out of the cartridge, but I should ask, what is your end goal? Unless you reload, or have access to free ammo or something, 300blk is pretty expensive from an ammo standpoint compared to .22LR/9mm/45acp if you are only going to shoot subs. Although to be fair, it is extremely cheap to get into if you are already into 5.56. A barrel/MD, a gas tube and maybe a couple of 5.56 Lancer mags, and that is it unless you want a new rail as well. 338ARC throws a bigger bullet if this is for hunting, although it requires specific mags (they are not always 100%) and a new bolt. |
|
We are getting hogs under 300 yards, Mostly under 150 yards. Normally I use 7.62x39, I’m thinking a suppressed 300 BO might be fun. At those distances, x39 or 5.56 works fine. Just want it to be quieter now. I will NOT be dumping a lot of rounds through this. |
Words fall from your mouth like shit from ass.
|
I have a 7.5" upper with 1:7 twist. It stabilizes 225 grain Hornady ELD-Match bullets just fine. I reload my own and put those over 12.1 grains of CFE Black for right at 1020 FPS. My particular upper will cycle subs without a can, so it's over gassed. I added a Superlative AGB to tune it with the suppressor on (it's a dedicated sub only shooter and I run suppressed 100% of the time). Bullet weight doesn't matter for stability, physical length of the bullet is what matters. |
AR Sponsor