7.62x39 subsonic Loads

[N555]

You will find even the pointiest 155gr bullets that you would have to single feed into an AK will stabilize at high subsonic even through a silencer with 1:9.5 twist.

 

[MagnumPI_357]

Hi all,

Thanks for all the advice, here are the results from sunday's tests

155gr FP lead head loaded with titegroup and a large rifle primer. Sandbagged in the rain at 25m, wasnt trying that hard to aim as I was more interested in the chrono results!

4.0gr 978, 965, 973
4.5gr 1045, 1007, 1036, 1024
5.0gr 1104, 1110

the chronograph didnt trigger on the 3rd shot but I guess it was around that speed.

Groups are okay, the 4.0&4.5 had good groups with an outlier low left. The ones with 5gr were key holing, so something strange going on there. Maybe transonic, or just not gripping the rifling?
Checked the barrel afterwards and no signs of leading.

I'm going to load a few more around the 4.5gr mark probably 4.3, 4.5, 4.7 and try again, will be more careful on the crimp this time.

Anthony

 

[MagnumPI_357]

An update on this load I tried the 4.3 4.5 and 4.7 grain loads and had consistent velocities of about 1025, 1035 and 1070. Groups were okay but not great at 25m. all groups stringing low left to high right. I was still getting oval bullet holes.
I tried some bullets sized to 312 over the weekend with 4.5 and 4.7grs at 50m, bullets seem to be stabilised now but the velocity dropped to 996 & 1010. I had a suggestion that the better fit in the barrel might need a bit more powder behind it?

 

[MagnumPI_357]

Forgot the picture of the 4.7gr titegroup group at 50m, I'm wondering if the fliers low left are cause during seating the bullets?
They are lead bullets designed for gas checks I'm not using, they are tricky to get started and sometimes it shaves a bit of lead off. Would they always fly in the same direction?