300 Blackout - Random build

[dareposte]

Most of these parts came out of my spare parts / take-off parts box, looking forward to finding some dies in-stock and getting to touch this one off.

I live in MI and so can't legally have a suppressor, but you better believe the minute I move out of state the first thing I get on order will be a can.

 

[dareposte]

Re: 300 Blackout - Random build

Lower: Mil-spec random brand forged
Upper: Mil-spec random brand A3 flat-top
Trigger: RRA fixed
Stock: Magpul OE
Buffer tube: Random commercial spec
Buffer spring: 11" / carbine spring
Barrel: 16" CMMG w/ pistol gas system
Forearm: YHM rifle-length free float tube
Sight: Primary Arms Micro Red-dot
Grip: Magpul

 

[Dirty D]

Re: 300 Blackout - Random build

Who gives two shits what it looks like, post some groups!

No seriously, post some groups.

 

[animalmother85]

Re: 300 Blackout - Random build

The wheels are in motion for my first suppressor. I'm buying an AAC 762-SD-N6 for an SBR'd PWS Mk109 (300 Blackout). I'm pretty pumped about it.

 

[AXEMAN]

Re: 300 Blackout - Random build

thanks for that barrel tip. ill be ordering one soon.

 

[dareposte]

Re: 300 Blackout - Random build

Got this shooting today, no groups to post as I'm just trying to get the velocity worked up first.

The only powder I had on hand was h4198, so that's what I attempted to use for both sub-sonics and super-sonic loads.

Results were all pretty slow.

Sub-sonic loads I tried (H4198, 208Amax, LC Brass, Mag primer)
Charge, velocity
10.0gr H4198, 755 ft/s
11.0gr H4198, 845 ft/s

Super-sonic loads I tried (H4198, 150gr Sierra soft points, LC brass, mag primers)
Charge, velocity
13.0, 1228 ft/s
14.0, 1303 ft/s
14.5, 1297 ft/s
15.0, 1365 ft/s
15.5, 1457 ft/s
16.0, 1492 ft/s

None of the loads had any pressure signs, the subs would cycle the bolt most of the time but not always, and everything above 15.0gr cycled the bolt for the supersonics.

AXEMAN - I'm pretty pleased with the barrel so far, it seems well made and was pretty affordable. Hope your build goes well, I'll be watching for a picture one of these days.

 

[AXEMAN]

Re: 300 Blackout - Random build

hey try quarterbore.net they have a section on loads for subs over there. guys are using pistol powders i thought? ill be getting the barrel next, hopfully in a few weeks.

 

[rsilvers]

Re: 300 Blackout - Random build

1680 powder for subsonic.
H-110 for supersonic.

 

[dareposte]

Re: 300 Blackout - Random build

I've got a metric shit-ton of Power Pistol, wonder if that could work for a subsonic load? Probably no hope of it cycling the bolt properly.

I'll keep my eye out for the any of the powders you suggested Rsilvers, but so far I haven't seen anything around locally to pick up a pound. When I make a big powder order I'll get a keg.

 

[rsilvers]

Re: 300 Blackout - Random build

It won't cycle.

In a Blackout gun, with a 208 to 240 grain bullet - RE-7, 4198, or 1680 for an AR. N110 for bolt guns and some Whisper guns.

300 AAC Blackout guns are being set up with smaller gas ports and designed to run with 1680 type powders so that you can shoot full power and subsonic ammo in the same upper without needing an adjustment.

RE-7 is hard to fit though with some of those bullets and shorter seating depths. 1680 is the most versatile in that it should work with all bullets in that range.

 

[dareposte]

Re: 300 Blackout - Random build

Thanks for the advice, I'm really interested in the subsonic loadings for it so I guess I'll start with a couple pounds of A1680 and see where that gets me.

 

[Sgt_Jamez]

Re: 300 Blackout - Random build

Dareposte and Axeman... how are those CMMG barrels working out?

I ordered mine yesterday, shipped today. Still going to be a while before I get all the parts together.

My buddy has a Noveske 16" w carbine gase and we've done some loads using H110 and it's cycled eveything fine.

 

[wcrenz]

Re: 300 Blackout - Random build

H-110 for subsonic also. Supersonic loads aren't as picky on powder. That cartridge was designed aroung H-110 and a 240 MK. The amax 208 works fine but not for animals. Give credit where its due long live the 300 Whisper!

 

[rsilvers]

Re: 300 Blackout - Random build

H110 is not an appropriate powder for subsonic 300 AAC BLACKOUT - at least not for ARs the way AAC and Noveske are building them.

That kind of load was the way of the 300 Whisper(R), but that is one of the things we fixed with 300 AAC BLACKOUT. With the new guns and ammo, the gas is set to work with subsonic and supersonic without requiring adjustment - but H110 subsonic will not work. If you enlarge your gas port to make H110 work subsonic, then you can no longer shoot full power ammo.

A1680, 4198, and Re-7 seem best. 5744 may work also, with 220 and higher.

 

[AXEMAN]

Re: 300 Blackout - Random build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sgt_Jamez</div><div class="ubbcode-body">Dareposte and Axeman... how are those CMMG barrels working out?

I ordered mine yesterday, shipped today. Still going to be a while before I get all the parts together.

My buddy has a Noveske 16" w carbine gase and we've done some loads using H110 and it's cycled eveything fine. </div></div>

you will have your barrel before i have the $$ to order, lol. but ill let you know. should be fine, they make pretty good barrels there

 

[dareposte]

Re: 300 Blackout - Random build

I over-annealed all my brass and ruined it (d'oh) so I'm back to square 1 with having to make it from 5.56mm brass again.

I determined that H4198 is not a good powder for supersonic loads, but it works fine for subsonics and fills the case nicely.

I have picked up a pound of WW296 to try for some supersonic loads, it's nearly identical (if not actually from the same machine) as the H110, but cheaper and easier to find. My future plans revolve around using this powder.

 

[rsilvers]

Re: 300 Blackout - Random build

They are the same. I always thought H110 was much easier to find than W296. Midway does not sell 296. Grafs has both but H110 is a little cheaper.