I have an original Sharps in 40-70 SS and marked 40-2 1/2 on the barrel.   Barrel and receiver serial umbers all match correctly.  The groove diameter is about .414 and the bore about .407.   This is a late Sharps rifle built by Sharps (not Meacham),  probably on a returned carbine frame.   The barrel has 6 narrow lands and a 1 in 20 twist.   The cartridges that came with the rifle are made up from 9.3 X 74R brass.   Careful measurements tell me that this rifle is actually chambered for the 40-70 straight  Ballard.  I had Accurate Moulds cut me a grease groove mould of about 375 grains with a diameter of .415 and am looking forward to shooting it this spring.

Those paper patched bullets would really have to bump up!  but I guess that was pretty standard.

Regards,
George

Full diameter grease groove bullet seats just fine.   I'm using fixed ammunition.  There were 35 or 40 loaded rounds that came with the rifle.  I pulled one of the bullets and miked it before ordering the mould.   Also slugged the bore.   I didn't realize that they were 40-70 Ballard straight until I reloaded them and found that there was no way they could be reloaded with the 40-70 SS dies I already had.   I managed to get them reloaded by just neck sizing and using a  mish-mash of various dies for the neck sizing  and  seating.   I'm glad I made notes so I don't have to figure it all out next time.   

George

Interesting;  you have me wondering now if perhaps my rifle was chambered for the Ballard cartridge speciffically so that grease groove bullets could be used.  I always check my reloads to be sure they will chamber and these most certainly do.  Maybe it is the design of the bullet I have.

George