School me on 300 Blackout barrels

SouthTXBowhunter

SouthTXBowhunter

New member
I've decided to build a .300BK SBR (my wife wants one and I think it'd be fun for killing coyotes) and I'm trying to shop for a barrel. This will be a dedicated suppressed rifle. I'm hoping that some of y'all can school me on what to look for in a barrel. Particularly, I'd like to know about twist rates and those rates in relation to a short barrel. I'd like to build something with a barrel length between 8.5" and 10.5" - to keep it light and handy for my wife. It'll have a 7" suppressor on it that's pretty durn light but my wife is only 5' tall. So, I really need to keep it as short as I can; also, do that our 2 boys can handle it.

I know that Noveske uses 1:7 twist but I saw some affordable barrels from Rainier that use a 1:8.5 twist. I'm concerned that a 8.5" barrel, with a 1:8.5 twist, won't be able to stabilize a bullet enough to get good accuracy out of it at 100-125yds. They offer this barrel, though, along with a 90 day guarantee of satisfaction. That' makes me think that it'd be a pretty good barrel; but I just don't know.

Any insight/help/advice y'all could share would sure be appreciated!!
 
if you're going to be doing primarily subs - go with the faster twist rate. a 1:8.5 may have stability issues with heavier jacketed bullets or some of the longer all solid coppers.

a 7 twist will stabilize basically everything. i think its sig that is now producing a 6 twist barrel if that tells you anything. basically faster twist is better when lobbing long heavy bullets.

a 8 or 8.5 twist barrel should have no problem stabilizing a 208 amax or 220 SMK, even in the barrel lengths your considering. the 220 SMK will probably be right on the line and considered the limit for that twist range.


one thing to watch out for is making sure the gas port isnt oversized. some barrel manufacturer's are putting .125" ports on even their pistol gas barrels. this under supersonic supressed fire can lead to overgassing issues - outrunning the mag spring, beating up your brass, etc. I think most pistol barrels are in the .090 to .098 range. I never measured my 9" aac barrel before i put the gas block on.

if the barrel you select does have a larger port on it, just know that you may need to look at an adjustable gas block in the future.


FWIW - make sure you have a H2 buffer & m16 bcg with that short barrel. Unsuppressed you probably wont notice a difference, but again when discussing suppressed supersonic, the extra weight will prevent carrier overrun feed related issues.


a while back when i built my pistol, AAC was clearing out some of ther 9" melonite barrels for about $250-$275 range, which included a 51T brake. you may be able to find a dealer that still has one in stock. this is considered pretty much the go-to barrel by most of the blackout crowd for barrels in that size range - and at that price its a steal. I sold the brake off from mine for around $80 alone, so my in-hand cost for barrel, gas block and tube was under $200 for a very very premium grade barrel.

HTH
 
Originally Posted By: Plant.Oneif you're going to be doing primarily subs - go with the faster twist rate. a 1:8.5 may have stability issues with heavier jacketed bullets or some of the longer all solid coppers.

a 7 twist will stabilize basically everything. i think its sig that is now producing a 6 twist barrel if that tells you anything. basically faster twist is better when lobbing long heavy bullets.

a 8 or 8.5 twist barrel should have no problem stabilizing a 208 amax or 220 SMK, even in the barrel lengths your considering. the 220 SMK will probably be right on the line and considered the limit for that twist range.


one thing to watch out for is making sure the gas port isnt oversized. some barrel manufacturer's are putting .125" ports on even their pistol gas barrels. this under supersonic supressed fire can lead to overgassing issues - outrunning the mag spring, beating up your brass, etc. I think most pistol barrels are in the .090 to .098 range. I never measured my 9" aac barrel before i put the gas block on.

if the barrel you select does have a larger port on it, just know that you may need to look at an adjustable gas block in the future.


FWIW - make sure you have a H2 buffer & m16 bcg with that short barrel. Unsuppressed you probably wont notice a difference, but again when discussing suppressed supersonic, the extra weight will prevent carrier overrun feed related issues.


a while back when i built my pistol, AAC was clearing out some of ther 9" melonite barrels for about $250-$275 range, which included a 51T brake. you may be able to find a dealer that still has one in stock. this is considered pretty much the go-to barrel by most of the blackout crowd for barrels in that size range - and at that price its a steal. I sold the brake off from mine for around $80 alone, so my in-hand cost for barrel, gas block and tube was under $200 for a very very premium grade barrel.

HTH


Thanks for all the info.- that's exactly the kind of stuff I'm looking for. I'm a sucker for 5R rifling (my custom bolt guns) so those Rainier barrels caught my eye; but a single (barely) twist before leaving the barrel sure didn't seem like much stabilization. Since this is my first 300BK, I have no idea if I'll be shooting subs only or both.

Lots to consider. Thanks again!
 
Listen to plant. I run my 9" AAC, 1/7 twist suppressed with a JP Silent Capture spring instead of the h-2 buffer though. SWEET.
 
Originally Posted By: vanhornetListen to plant. I run my 9" AAC, 1/7 twist suppressed with a JP Silent Capture spring instead of the h-2 buffer though. SWEET.

Yessir. I'm probably going to use the JP SC as well - I've had one in one of my ARs since they first came out; and I love it. Just depends on finances whether it'll be there from the get-go or be an upgrade later. We started down the NFA path back in October and outfitting everyone in my immediate family, prior to 41p, has become an expensive undertaking. Lol!

Sure wish I could find one of those AAC-made barrels. I'll prolly end up with a Noveske.
 
i have a form 1 suppressor build waiting for a stamp as we speak. that may well be the thing that gets me to jump on the JP SCS bandwagon as well.


it depends on how much i grow annoyed with the "sprong!"

i know i know.. everyone says embrace the sprong!... but it might actually get annoying once the gun gets quiet
cool.gif
 


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