I recently had a friend accompany me to the range to sight in his SKS carbine,
once we got too the range his carbine produced consistently poor accuracy,
it took awhile but we eventually found and isolated the,
the primary reasons his ammo produced 12" -15" 100 yard groups.
sort version, the carbine he owns has a .311 bore diam.
and he had use a rather slow burn h4831 powder and
.308 diameter, 130 grain bullets.
he had purchased in 500 count zip loc bags at a local gun show ,
(manufacurer un-known) cheaply to use in his SKS reloads
those two factors combined just don,t work well in his SKS
https://www.speer-ammo.com/products/...le-bullet/2217
these speer 150 grain .311 diam worked far better.
over 25 grains of accurate 2015 powder
https://www.americanrifleman.org/art...762x39-mm-m43/
http://marvinstuart.com/firearm/Manu...%207.62x39.pdf
http://www.gunsandammo.com/editorial...7-62x39/250274