I have a 15 yr old HBAR for which I reload. It has a 1/7 barrel. I have had no luck developing a load for 69 gr SMK's which produces better than 1 1/2 to 2" at 100 yds. I have found several 52 gr loads which perform well and a couple of 77 gr loads which are spectacular.
25.3 gr Varget
26.0 gr Varget
25.5 gr 748
25.3 gr Re15
24.3 gr AA2520
20.3 gr IMR4198
22.5 gr H335
25.0 gr Vit N140
All loads are in Lake City brass, cleaned, trimmed, reamed/deburred, and polished. Primers are Win small rifle. AOL is 2.255".
My befuddlement is due to the fact that bullet weights above and below 69 gr work great.
Any similar experiences or advice?