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JasonMPD
Senior MemberPosts: 6,583 Senior Member
8.5” 300 Blackout 50/100 Yards — Potential.

Here’s my yearly post—haha.
I recently put togethet a 8.5” 300 Blackout SBR to try out as a possible “low signature” hunting gun. It’s suppressed with a Crux Nemesis 30cal/338cal suppressor (bored for 338, backwards compatible effectively to 30cal, smaller is less effective due to blow-by).
Since the SBR parts were sourced from varied places, I opted for an adjustable gas block to try and author in some reliability since I did not select nor drill/ream my own gas port. The gun will be suppressed one hundred percent of the time so increased back pressure will aid in cycling reliability. Being a little over gassed helps 300 B/O anyhow.
Atop the rig is a Vortex PST (gen 1) 1-4x, second plane reticle, with their TMR reticle. It’s subtended 6 MIL in all 4 directions and has an illuminated center portion for CQC at 1x.
Many 300 B/O rifles are reliable but not so accurate. Not in the context of supersonic calibers that is. The subsonic game is a different thing. 100 yards for subsonic is like 600-800 yards for supersonic projectiles in a manner of speaking. It’s for close work and heavy bullets are name of the game for effective wounding.
I randomly grabbed some Hornady Black 208gr AMax subsonic. My Magnetospeed measured them reluctantly at 981 FPS, average. Slow projectiles give Magnetospeed sensors a tantrum and they had to have their sensitivity set to “high”.
I was testing out a Maxim Defense PDW style stock and I won’t be using it on this rig after all. Cheek weld is dicey and it’s design doesn’t fit the mission of this SBR. It’s cool kit, but for another purpose perhaps.
I had similar grouping at 50 and 100 yards. Typical? Actual? Weird? I’m not sure. The stock gave me very poor consistency in the shoulder pocket and offered little cheek weld. But if it never does worse than it did today I’m all for it. It’s acceptable nevertheless.
I’m not sure when I’ll get to plug a few in a critter or two, but I’ll report back when I do. Coyote first. We’ll see what a subsonic AMax does.
Cheers.



I recently put togethet a 8.5” 300 Blackout SBR to try out as a possible “low signature” hunting gun. It’s suppressed with a Crux Nemesis 30cal/338cal suppressor (bored for 338, backwards compatible effectively to 30cal, smaller is less effective due to blow-by).
Since the SBR parts were sourced from varied places, I opted for an adjustable gas block to try and author in some reliability since I did not select nor drill/ream my own gas port. The gun will be suppressed one hundred percent of the time so increased back pressure will aid in cycling reliability. Being a little over gassed helps 300 B/O anyhow.
Atop the rig is a Vortex PST (gen 1) 1-4x, second plane reticle, with their TMR reticle. It’s subtended 6 MIL in all 4 directions and has an illuminated center portion for CQC at 1x.
Many 300 B/O rifles are reliable but not so accurate. Not in the context of supersonic calibers that is. The subsonic game is a different thing. 100 yards for subsonic is like 600-800 yards for supersonic projectiles in a manner of speaking. It’s for close work and heavy bullets are name of the game for effective wounding.
I randomly grabbed some Hornady Black 208gr AMax subsonic. My Magnetospeed measured them reluctantly at 981 FPS, average. Slow projectiles give Magnetospeed sensors a tantrum and they had to have their sensitivity set to “high”.
I was testing out a Maxim Defense PDW style stock and I won’t be using it on this rig after all. Cheek weld is dicey and it’s design doesn’t fit the mission of this SBR. It’s cool kit, but for another purpose perhaps.
I had similar grouping at 50 and 100 yards. Typical? Actual? Weird? I’m not sure. The stock gave me very poor consistency in the shoulder pocket and offered little cheek weld. But if it never does worse than it did today I’m all for it. It’s acceptable nevertheless.
I’m not sure when I’ll get to plug a few in a critter or two, but I’ll report back when I do. Coyote first. We’ll see what a subsonic AMax does.
Cheers.



“There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.” – Will Rogers
Replies
Kool gun
Supersonic... The muzzle report is something between ouch and Jesus, Mary and Joseph. The brake also expelled any unburned powers sideways at hyper speed. Ouchy on the forearms. That’s the nature of a 8.5” blaster though. Braked 10.3” 5.56 guns will do similar, but louder.
Subsonic... The muzzle report is no issue. It’s not absent by any means, but ignorable. Either way the flash hider will be preferable.
The supers I shot were 110 VMax. 8.5” got them to 2100 FPS. About 2-3 MOA grouping.
I will say though run supersonics through your suppressors after a subsonic range session to clean them out though.