Browning 1885 BPCR

[Robert L]

I have been using a Pedersoli Sharps for many years but recently bought a Browning 1885 BPCR (45-70). I am shooting a 550 grain GG bullet that worked extremely well in the Pedersoli but I seem to be having some issues getting it to work in the Browning.

The Bullet: 1.41" OAL
Nose .449
Driving band .456
Remaining bands .458

Nose pour HOCH mold. 20/1 alloy

Seated over .060 Walters wad and 63 grains of FFG GOEX.

In the Pedersoi I seated the bullet with two bands out of the case. With the Browning I have to seat the bullet with the driving band and the first groove out of the case. In other words about an 1/8 of an inch deeper.

In order to get a feel for what works and what doesn't I I compressed the charge enough to get the bullet to chamber just touching the rifling. I varied the powder charge by 1 grain up and down but found the 63 grains seemed to give the best consistency. Unfortunately this was all done at 100 yards. I know that is not ideal but it was all I had available reasonably close to home.

At 200 and 300 yards (different range) it seems to hold 1 - 1.5 MOA. At 400 and 500 yards it's all over the place. Nothing even approaching 1 - 1.5 MOA.

My question then is this: Does the Browning require a certain dimension bullet, powder, loading technique to preform at its best and hold acceptable group size at all distances?