Question for the hive mind who have a Wolf T91 Piston upper. Took it out and frankly, was dismayed with the accuracy. After zeroing at 25yd.s with Federal 55gr FMJ, Aimpoint red dot., I got around 6in Groups at 100 yd.s (5rd.s) from the bench using sandbags. I had several old Tula 62gr. rds that I tried and the groups shrank down to slightly over 2 inches. It’s supposed to have a 1:7 twist, which I thought was good with 55gr. ammo from what I have read, but is this not the case?

BTW, tried the federal ammo in the wife’s lightweight AR-15 and got a 5 rd 1 1/2” group at 100yd.s, so the ammo appears fine.

I got mine in 2018, so I don't know if there are any variations in the batches.  Mine's never shot better than 2 inch groups at 50 yards.  Most accurate with Norma tac 223 55gr in the black box and Frontier 62gr bthp.

I've got the 12.5" and never shot it for groups other than when I zeroed it at 50m. Groups were ~2" at that distance with 55gr Wolf Gold using iron sights shooting from a table with front rest.

I had a 12.5" 1/7  twist that would not even stabilize 62 grain or 68 grain bullets at 50 yards. You want a 75 grain bullet with 1/7 twist, especially with shorter barrels.

A 20" 1/7 barrel will stabilize the lighter bullets better than a 16" at 100 yards, the accuracy will not be ideal though. You will get tighter groups with the heavier bullets.

I would just run the lighter stuff for plinking up close and use heavier bullets for accuracy when running 1/7 twist.

Thank you for the input gents. It’s a 16” barrel btw. I’ll be getting some heavier FMJ-BT ammo and give it another go.

This is not necessarily true.  Heavier bullet doesn't make it more accurate.  It varies.  Barrels can be different.  Many time people go heavy because of distance (wind and velocity) changes.  Match grade ammo in 55, 62, 77 can all be just as accurate generally speaking. I have Wilson barrel that shoot 69gn FGMM more accurately then 77 FGMM.  Each gun is different

This ^

My other rifle is an Armalite with 1/9 twist.  It shoots small groups with 77gr and 62gr bthps.   Does not like the 62gr green tips, gets larger erratic groups.

Try different types of ammo to find out which one yours like.  Each barrel is different.

I'd be really happy with a little over two inch group at 100 yards with old Tula ammo. Try more different loads and manufacturers.

Update. Well it likes Aussie 62gr. surplus M855/SS-109 and really loves IMI 77 Grain OTM. Very respectable groups, moreso with the 77.  Still pretty bad with any 55gr. M193 mfg I’ve tried so far, but will keep trying..