Barrel length for 300 Blackout

Crunchy Frog · Dec 30, 2014

Thinking of registering an AR lower as an SBR. I need to specify caliber and barrel length on the Form 1 and I'm considering building a .300 Blackout upper. I might eventually get a suppressor.

I see lots of barrels in the eight, nine and ten inch range. Found one source that said the cartridge was designed around a nine inch barrel but I don't see as many nine inchers out there as I do eights and tens.

What advice would you give? Thanks in advance.

Tigerstripe · Dec 30, 2014

i just got an 8.5 in barrel in 300 Blackout.

my responce is on the SBR. i dont know about now but when i got mine i talked to the BATFE.
i was told to list the bbls i would use on it.
all i had planned was 10.5 in 556 but i listed a 5.5 22, 10.5 pmm and 10. in 556 also even though i didnt have them.
he said if i made more to send an updated list but i ASSUME that listing a 5 inch might cover a 10 inch. could be wrong though.

since then i bought my full auto and am not required to list bbls for it so i wonder about updating the list since its legal to have any bbls for full auto.

so i guess im saying just call. they are happy to answer questions.

i did make one mistake that caused them to send back the paperwork. dont do this.
in the caliber box i put 223/556. papers came back with a note... pick a caliber.
i thought that was a little picky but....

Clicker · Dec 30, 2014

Mine is a 9" because at the time SC allowed night hunting with pistols of barrels no longer than 9".
These days I think you'd be fine with what ever you like from an 8" to 10". Get a can it's a nice round to shoot suppressed.
For the record I didn't list any additional calibers on my form.

Tigerstripe · Dec 31, 2014

Clicker, when did you do that form?

i figured they may have changed the need for a list in the last 4 years or so.

maybe i mentioned more bbls and he made up some rules for me.

Clicker · Dec 31, 2014

TS I submitted several forms in Oct 2013 and they were approved July 2014. They got kicked back for corrections on my info because I abbreviated my first and middle names, had to spell them out.
If you make a permanent change to the barrel length or caliber then you need to notify the ATF. Otherwise swap uppers around at will as long as you can return the gun to it's configuration as listed on the form you're good to go.

Tigerstripe · Dec 31, 2014

cool.

but dumb in its own governmental way.

pay $200, wait for acceptance, ahhh do i change THIS barrel or just get another?

:lol: :roll: :roll:

Crunchy Frog · Jan 1, 2015

Update; I went to the range with a friend who let me try his 10.5" .300 Blackout pistol. I was able to shoot subsonic and supersonic ammo, both with and without a suppressor.

It was not unpleasant to shoot unsuppressed with supersonic ammo. That's good news since I can probably afford to register my lower and then buy a short upper but can't buy a suppressor immediately.

This upper is one of a couple that my friend purchased from Hardened Arms. They stock 8.25" and 10.5" short uppers in .300 BLK. Website cost is $315 and $345 respectively. I don't think I can build one for much less.

This company also sells on Gunbroker; I just watched a 10.5" 5.56 upper sell for less than $250.

Any experience out there with Hardened Arms?