To Buy or to Smith the barrel?

[TheGameMaster]

I want a 9" barrel for my 300 BLK SBR Build. I have a 16" barrel now. Is it cheaper to have a gun smith cut down and thread the 16" barrel, or cheaper to buy a 9" threaded barrel? Also, does anyone know if 1:8 twist is any better for a supressed SBR 300 BLK or is 1:7 just as good?

Thanks,

Rodney

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[oli700]

If you cut the barrel you will have to address the gas port as well . Dwell time will be off for the port .

I think the faster twist the better for suppressed considering heavy, long bullets are easier to get subsonic

 

[TheGameMaster]

The current barrel already has a pistol length gas port, and it's 1:8 twist. I haven't seen any 9" barrels that are any faster than 1:8. My role for this gun is for the lighter weight in carry, so I can take critters up to 200 yards quietly (or, more accurately, quieter). At 9" it will max out the burn on the 300 Blk, and provide space for a carbine floating hand guard for a grip, etc. Add the 6 inches of silencer to it, and we are back to a 15" barrel. So my question is still... which is cheaper. Cutting this down or buying a new one? I've seen 9" barrels online for $180 for a 1:8, but I've also seen 8.5" ones at 1:7 for as little as $99.

 

[krivey]

I would buy a new barrel and look to recover some cost by selling the 16". My 8.2" noveske barrel is 1:7 and that is more optimized for 220gr bullets, although the 1:8 should have no problem stabilizing the 220's. If the plan is to run mostly heavy subs, your best bet is to go 1:7. Either will work though.

 

[v0lcom13sn0w]

buy a barrel.

build another one with the other barrel

 

[Mygrainman]

definitely sell and buy a different barrel... you'll easily loose less in depreciation than the $50-$100 it would cost to have it cut/threaded/recrowened/refinished. You'll be waiting a while too, all the decent Smith's are backed up for months.

I'd stick with 1:7 although it doesn't matter a ton. Faster twist is better for the larger and slower moving projectiles in subsonic ammo.
What brand is your current barrel?
If you've already built the loweras a rifle, you gotta consider the SBR/Pistol/rifle laws as well.

 

[v0lcom13sn0w]

im 99.999% sure my 10" 300blk barrel is a 1:7.its a ballistic advantage barrel with a pistol length gas system(the only way id ever go with 300 blk)

i run handloaded 208gr subs thru my can. its accurate.

 

[Mygrainman]

My 8.3" Balistics Advantage Hansen profile 300bo is 1:7...
It's hellla accurate...both super and subs

 

[TheGameMaster]

I was wondering about going less than 9 inches. I know one website had their 8.5" on sale for only $99. Considering the cost of the tax stamp, the cheaper the better. It was my understanding that if the barrel is less than 9 inches, you loose combustion pressure (the powder isn't all burned). Would that half an inch make a lot of difference? Especially with a can on it?

Rodney

 

[Velzey]

Velzey votes for cutting it down!

 

[Mygrainman]

According to this... you'll loose about 65FPS between 9" and 8" so maybe 30fps down to 8.5"... that's with supers.
I wouldn't hesitate to go with an 8.5" bbl. but don't go cheap. Mygrainman's first rule in AR building is to always build around the barrel. The extra $100+ for a premium barrel is a no brainer. You can skimp anywhere else without sacrificing accuracy, but your gun will only ever be as accurate as your barrel.
If you are spending the time and money on SPRing the build, your gunna want to make sure you really like it.

 

[Mygrainman]

Velzey votes for cutting it down!

Great advice from an impartial observer...

 

[titsonritz]

If you cut the barrel you will have to address the gas port as well . Dwell time will be off for the port .

I think the faster twist the better for suppressed considering heavy, long bullets are easier to get subsonic

This right here. It all starts with the proper port size. Unless you know what your barrel is and have a specific reason to chop it, sell it and buy a new one

 

[titsonritz]

The current barrel already has a pistol length gas port,

He is talking about the port dia not just the position of the port.

Also, are you sure that 16" barrel has a pistol (4") length gas system and not a carbine (7") length? Sounds weird to me.

 

[Mygrainman]

He is talking about the port dia not just the position of the port.

Also, are you sure that 16" barrel has a pistol (4") length gas system and not a carbine (7") length? Sounds weird to me.

Most 300bo even 16" have pistol gas.. not weird at all.
......Well it is kinda weird, but not uncommon.

 

[oli700]

Most 300bo even 16" have pistol gas.. not weird at all.
......Well it is kinda weird, but not uncommon.

Yep, due to the use of magnum pistol powder instead of rifle powder . It needs to have the port way down by the chamber to get all the pressure it can to cycle the bcg..... that's why dwell time is an even bigger factor on Blk

 

[Mygrainman]

Yep, due to the use of magnum pistol powder instead of rifle powder . It needs to have the port way down by the chamber to get all the pressure it can to cycle the bcg..... that's why dwell time is an even bigger factor on Blk

Yes... and as such, different buffer weights, and an adjustable gas block may be necessary to get consistent cycling with different ammo and w/wo supressor... But we love our blackouts anyway..
I just bought mine a new piece of hardware to help pass the time while I wait for my supressor to be freed(6.5 months and counting)

 

[oli700]

Nice.
they have their place for sure. Pretty versatile , I don't own one but built a couple and really like shooting them . Reloading for them a good time for a reloader too, lots of options to play with .

 

[titsonritz]

Most 300bo even 16" have pistol gas.. not weird at all.
......Well it is kinda weird, but not uncommon.

Interesting. I have never messed with .300BLK. I did a quick search and while some did have pistol length, most I found were carbine length and the only one 16" w/ pistol length I could find from a manufacturer I would consider reputable was Noveske.

Rifle Barrels - AR-15 - .300 Blackout / Whisper - Faxon Firearms
https://www.brownells.com/rifle-parts/barrel-parts/index.htm?avs|Make_3=AR-15&k=300+carbine&ksubmit=y
300 blackout barrel - MidwayUSA
Lo-Pro Gas Block Barrel, 300 AAC Blackout

but regardless the principle is still the same and as stated below...

Yep, due to the use of magnum pistol powder instead of rifle powder . It needs to have the port way down by the chamber to get all the pressure it can to cycle the bcg..... that's why dwell time is an even bigger factor on Blk

a pistol gas system, would make matters worse in that case.

 

[oli700]

a pistol gas system, would make matters worse in that case.

Why ? It needs to be closer to the source of the pressure because it makes less pressure than , for less time than smokeless rifle powders .