Thread: Subsonic 308 project

I got hold of some of Robert's (@shooternz) 151gr cast lead bullets and gave them a whirl this morning. Here's the outcome.

I started at 9gr of Trail Boss and was at 1200fps. So I dropped the loads down in 0.5gr increments until I dropped below the sound barrier, and then by 0.2gr to make sure. So I settled on 7.8gr of Trail Boss and made up five rounds.

The first cartridge I over did the seating depth, so I gave it some taps with the puller and long story short buggered it up a bit. The neck tension would have been looser than it would have with one clean pass through the seating die, and the bullet was a bit deformed by the time I'd finished. In the image below, its the one off to the bottom right.

Shot #1: 1070fps
Shot #2: 1081fps
Shot #3: 1081fps
Shot #4: 1089fps
Shot #5: 1085fps

Shots 2-5 had all gone in a tight little group so I went back to the shed and made up one more for a five shot group, all at the same seating depth with no buggering around.

Shot #6: 1089fps

Very happy with the outcome, 0.44MOA at 50yds (cheating, by leaving out the buggered bullet). Yes, there are 5 shots in those two touching holes. I think there's actually four shots in one hole, hard to tell.

Low ES, low SD. Can't ask for more than that. Definitely suggests that you have to be careful with neck tension. Considering its blowing a bloody gale here today, not too shabby for handmade bullet with a massive meplat.

The point of aim was the bullseye above the groups, the rifle is zeroed for my GameKing supersonic load. Wind was gusting strongly from about 8 o'clock.

Looking forward to getting back onto the goats with these subsonics.