Subsonic Grendel?

[Klem]

I am not saying don't do it, I am just saying it will not be without difficulty and proceed with caution.

Getting the Grendel subsonic is easy enough if you use a high bulk powder like Trail Boss. Say, a 160gn Sierra loaded to 2.165" and 8gns of Trail Boss should do it. That load fills 88% of the available space which makes it theoretically safe. It won't cycle the AR though.

Filling the case to 80%, cycling reliably while subsonic is the Holy Grail.

[LRRPF52]

Don't forget it is a bench rested gun and it is unusual. Normally averaging 1.2MOA so sometimes it's 1.5MOA. The barrel is a Ranier Ultra Match which also explains it.

I tried the 220 Pro Hunters a while back hoping the soft point would expand on flesh. Unfortunately it just goes through and out the other side like a laser beam. It gets slightly bent if hitting bone but that was about it. They also pigeon-toe inwards when loaded in a standard GI mag on the ribs. The 220SMK is more pointed so it does not touch the ribs like the blunt Pro Hunters. I find they are also more accurate.

Getting 300 BLK to shoot sub-MOA with tough jacketed magnum projectiles seems to verge on the unobtainable from some of the industry's best barrel makers and AR15 manufacturers.

Bill A. had a lot of interesting insight to share on it, having worked on it before there was even such a thing as Blackout, when it was still the Whisper. There are a lot of engineering challenges I would have never thought of that he has tackled dating back decades now.

[Klem]

Getting 300 BLK to shoot sub-MOA with tough jacketed magnum projectiles seems to verge on the unobtainable from some of the industry's best barrel makers and AR15 manufacturers.
.

I am unsure how to respond to this other than to say why don't we shoot a few groups and put that theory to the test. We need to define 'MOA'. How many rounds do these manufacturers call a group. This part is critical. Shooters and manufacturers often refer to 'sub-MOA' but how many rounds are we talking? We all know its usually three, especially when trying to impress others. I will swap the Aimpoint for a scope and bench rest at 100yds while not discounting any groups.

[Klem]

Getting 300 BLK to shoot sub-MOA with tough jacketed magnum projectiles seems to verge on the unobtainable from some of the industry's best barrel makers and AR15 manufacturers.

Bill A. had a lot of interesting insight to share on it, having worked on it before there was even such a thing as Blackout, when it was still the Whisper. There are a lot of engineering challenges I would have never thought of that he has tackled dating back decades now.

Here it is - Let's put to bed the notion that sub-MOA in the Blackout with magnum (heavy) bullets is unobtainable. Also the notion of 'uncorking' being of any practical concern in this calibre.

Quick test; 8 groups of 220gn Sierra Match Kings fired at 100 from a bench rest. 4 more groups of 110 Nosler ballistic Tips for comparison/control.









The heavy 220 Sierra's are well under MOA. This is my favourite subsonic hunting load and has performed the best out of all the heavy bullets I have tried.

The 110NBT was not doing too well and to be honest I am trying it for the first time. I have had better results with the Hornady 110's, the Speer TNT's and the Barnes 110TAC-TX (the Barnes are too expensive for this sort of test). I cannot explain the 3MOA large group...No doubt Uncle Klem was not paying attention.

Barrel; 12.5 Ranier Ultramatch.
Scope; Nightforce.
Trigger; Geissele.

220gn Sierra's @ 1,055fps.
110NBT's @ 2,275fps.