SBR project

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Mac11FA

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Well, I sold my 300 BLKOUT upper this past weekend and am thinking of building a 300 BLKOUT SBR. Guess I will start from scratch and attempt the Form 1 myself. I am gonna have to hustle so I can get it done before the July 1. I am on the fence on barrel length/twist as I want to hunt suppressed and also use for HD. I also like the look of the hand guard hiding the suppressor. What are your thoughts?
 
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freedom

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Mar 25, 2015
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I think anything longer than 9" does nothing ballistics wise for 300 subs.

I believe 1/8 has become the normal twist rate, but some companies still offer different ones.

I like the look of the hand guard covering the end, but only if it's never fired unsuppressed.
 

boss_hawg

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Jul 13, 2015
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I have a 300 sbr and here are some of my takeaways and observations.

I didn't hide the suppressor under the hand guard. my can is a sico SpecWar 762 which has a collar that needs to be turned to secure. so, unless there was a gap in the the rail/hand guard, I wouldn't be able to secure the can to the barrel. also, suppressors get hot and I don't want to be forced to use an oven mit when I shoot.

there have been a lot of studies to determine ideal barrel length for 300. current thinking is 9 to 10.5". I believe that Daniel defense, noveske, and advanced armament are all running either 9" or 10.3" as their standard shortest barrel. this is from memory so I may be mistaken. I went with an 8" or 8.5" cmmg barrel because it was steal. I haven't taken any mid-sized game with it yet, though.

I haven't and probably won't hunt with subsonic rounds. I don't think they are as effective at killing deer quickly and humanely. all bets are off for feral hogs, though.

I can't remember the twist rate of my barrel. I think it's 1x8 but who knows? it seems to shoot a wide range of ammo effectively with decent accuracy. I'll probably never shoot this beyond 200 yards with any ammo - sub or super - so sub moa was never my intent.
 

boss_hawg

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ok, I went and checked it...my cmmg is 1x7.

here are some pictures because ever thread needs pics.

b2d1e2ab5cbd2a5f73c10a6d89c5c51b.jpg


7b449d053fdc724d290230f83a6e7240.jpg
 

freedom

Sniper
Mar 25, 2015
1,522
885
113
Covington, Ga
Zip code
30014
I have a 300 sbr and here are some of my takeaways and observations.

I didn't hide the suppressor under the hand guard. my can is a sico SpecWar 762 which has a collar that needs to be turned to secure. so, unless there was a gap in the the rail/hand guard, I wouldn't be able to secure the can to the barrel. also, suppressors get hot and I don't want to be forced to use an oven mit when I shoot.

there have been a lot of studies to determine ideal barrel length for 300. current thinking is 9 to 10.5". I believe that Daniel defense, noveske, and advanced armament are all running either 9" or 10.3" as their standard shortest barrel. this is from memory so I may be mistaken. I went with an 8" or 8.5" cmmg barrel because it was steal. I haven't taken any mid-sized game with it yet, though.

I haven't and probably won't hunt with subsonic rounds. I don't think they are as effective at killing deer quickly and humanely. all bets are off for feral hogs, though.

I can't remember the twist rate of my barrel. I think it's 1x8 but who knows? it seems to shoot a wide range of ammo effectively with decent accuracy. I'll probably never shoot this beyond 200 yards with any ammo - sub or super - so sub moa was never my intent.

They are supposed to have devolved so bullets that reliably expand at subsonic speeds for 300aac. They are expensive, but I think they're out there now.
 

boss_hawg

Marksman
Jul 13, 2015
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They are supposed to have devolved so bullets that reliably expand at subsonic speeds for 300aac. They are expensive, but I think they're out there now.
but, in my internet research, for what that's worth, a subsonic 300 bullet that expands into petals works more like a broad tip arrow. if I'm hunting with a firearm, I want the round to cause massive tissue damage due to hydrostatic shock and drop my future meal in its tracks.

not saying that subs won't get the job done but I try to take game as humanely as possible. if that means I have to wear ear pro because of a super sonic crack then it's a sacrifice I'm willing to make.

I guess it's a personal preference thing.
 

Cudruln

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I am running a 9.5" on my 300 blk. Shot it for the first time this past weekend (obviously suppressed) and it was a blast. From what I have found on my research is anything over 10.5" is not doing anything for you. Are you looking to build a upper or you just going to buy complete?
 

Willy Leadwell

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Well, I sold my 300 BLKOUT upper this past weekend and am thinking of building a 300 BLKOUT SBR. Guess I will start from scratch and attempt the Form 1 myself. I am gonna have to hustle so I can get it done before the July 1. I am on the fence on barrel length/twist as I want to hunt suppressed and also use for HD. I also like the look of the hand guard hiding the suppressor. What are your thoughts?
I would go ahead and form 1 the lower now while you decide what you want in an upper.
 
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Mac11FA

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I am running a 9.5" on my 300 blk. Shot it for the first time this past weekend (obviously suppressed) and it was a blast. From what I have found on my research is anything over 10.5" is not doing anything for you. Are you looking to build a upper or you just going to buy complete?
I have not decided yet. I wouldn't mind building from scratch although if I could find a good deal on a complate upper, I may go that route. I was looking to go between 8.5 and 10.5 on the length and the shorter the better. I am thinking of a SBR varmint rifle.
 

Cudruln

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Hardened arms or radical firearms (pretty sure they sell 300 blk) has some pretty sweet deals on complete uppers. May be worth looking into.
 

Wiskey_33

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May 17, 2016
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I agree on keeping it short. My brother has a 16" 300 BO upper and even the subs in that barrel length are right at the limit. Some do go super. UMC sub ammo is a lot more consistent than the Federal AE Sub ammo.
 
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DevilDoc602

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