Bullet drift 7.62x39 Yugo

[RWBlue]

I am posting this on multiple forums to get some attention.

Let me summerize from the other forum.
When I shoot full power loads I am sighted in at 100 yards.
I think wolf goes left and yugo ammo goes a little right, but they are both on a paper plate at 100 yards.

When I shoot subsonics, I am WAY RIGHT. I am so far right, that I haven't figured out how far right I am.

I am shooting my Yugo AK, Gas off, Gemtech suppressor.

Trailboss powder
180gr RN Sierra bullets tumble
170gr RN Hornady bullets don't tumble
150gr SP (Remington? Winchester?) bulk bullets don't tumble

Here is my question:
Why is it going so far right? Bullet weight and speed?
Would a lighter weight bullet be close to being on paper?
Is this a problem because I am using a .308 bullet in a .311 barrel?

I was told to use .311 or .312.

I tried some Hornady 174gr .312 bullets with 9.5gr trailboss. They are still going right.


I have some 150gr .311 bullets. Do you think it will make a difference?

Do I need to change powders?

[LouBoyd]

What's the twist rate of your barrel? It may be hopeless to try to shoot any heavy subsoincs. AK's weren't designed for that. What altitude and temperature do you typicall shoot in. Denser air hurts bullet stability too.

Perhaps your subsonic loads aren't really subsonic and are in fact transonic.
Then they're likely to be very unstable and could go anywhere. I didn't see any chronograph readings in you post.

I'd suggest to Load some 150 grain flat base bullets down to 950 fps and see how they do. Then work back up in velocity until you start to see a shift in point of impact. You should expect have to re-zero when changing loads or adding a suppressor but you want to avoid any load where you see a large change in POI for a small change in the load.