I'm far from an expert, but I'm pretty sure all these rifles were free-bored at the factory."
"You can easily tell free-bore when you seat bullets to OALs of 3.30"+ and the bullets are still a ways from being engraved."
According to a vintage Lyman manual that used a Schultz & Larsen M65DL for load development, the rifles did indeed come free-bored. For the 7x61 Sharpe & Hart (
not the successor, Super 7x61), it states...
"The rifle used for this testing was free-bored. For rifles which do not have a free-bored throat, this data should be reduced a full 5%. Even then, max loading should be approached with caution"Accuracy loads for a 1:10 twist, 24" barrel S&L M65DL using Remington 9 1/2 primers are listed as:
139 Hornady Spire Point: 58.0 gr IMR 4350 (2949 fps)
150 Remington Ptd. SPCL: 57.0 gr IMR 4350 (2865 fps)
Max OAL (with bullet) is 3.190"
Other loads developed pushed velocities into the 3000-3200 fps range at the expense of accuracy.
Years later, Norma published faster loads using Super 7x61 brass and Norma MRP powder than can be located via internet searches. I am not a handloader so use at your own risk since this info is derived from pictures of a 50 year old manual I scrounged online. Would love to hear feedback in the future on current day results.
