I took my scoped YUGO M59/66 and my Chinese out back today and shot about 20 Rds. of my reloads I put together last night, I shot some five and ten shot groups with each, 50 yds. with the irons on the Chinese and close to 75 yds. with the scoped YUGO. I don't have the greatest scope on the YUGO but it's fine for hunting,cross hairs are a little to thick for my liking I will end up replacing it at some point. The load I used were made for the Laupa Berdan primed wooden bullet ammo you may have seen on some post or ammo web sites. It's first quality brass I simply pulled the wooden bullet dumped the old powder and replaced it with my own bullets and powder,Loading these Rds. cost me about 25 cents each thats about $10 for 40 Rds. to make you own custom ammo using either 123 Gr. SP or FMJ bullets or 150 Gr. SP if you prefer a heavier bullet.

What I started with
http://i76.photobucket.com/albums/j1/rhsikes/Ammo011.jpg

75 Yd. YUGO target 1 3/4" center to center
http://i76.photobucket.com/albums/j1/rhsikes/scan1-5.jpg

50 Yd. Chinese iron sight 7/8" center to center
http://i76.photobucket.com/albums/j1/rhsikes/scan2.jpg

How do the 150 gr bullets work in the SKS? Seems they would cause the bolt carrier group to really slam into the rear of the receiver since the gun was designed for 125 gr FMJ ammo.

Actually the weight of the bullet has nothing to do with how hard the bolt & bolt carrier recoil into the back of the receiver that is controlled by an entirely different operation mainly the recoil spring and the function of the gas system pushing the bolt carrier back.

HOT loads will cause the bolt and carrier to slam backwards into the receiver with more force and put more stress on the gas system but my loads are about 1 Gr. below MAX. The 123 Gr. FMJ is the most common bullet weight found loaded in the 7.62 x 39mm, a few use the 124 Gr. and Wolf make a 154 Gr. factory SP. The only 125 gr. I know of is the Sierra 125 gr. Prohunter in .310 dia.

As far as how the 150's shoot in my YUGO I will let my target speak for itself.
50 Yds. iron sights black squares are 1/2 inch
http://i76.photobucket.com/albums/j1/rhsikes/scan1-4.jpg

I know it's a cheap rifle, but I love my SKS.

I think it's about the only rifle I take every time I go shooting. :)