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?