CptCrl,

Unfortunately, these old British rifles can produce different ballistics, due to sometimes considerable variations in bore size and effective freebore, which can be different in each barrel in doubles due to bore and throat erosion.

Accordingly, the "guide books" can sometimes only provide a starting point.

For example, Graeme Wright (Shooting the British Double Rifle) gives an 83-gr load with IMR 4831 as developing a MV of 2070 fps which should be right on the money! But I have used an 80-gr load with that powder that regulated beautifully but gave an extra 100 fps of MV (2170 fps)!

First things I would do are;

* Slug both bores for actual bore dimensions(once you know that, you could cast around for pills that may be a better match for your rifle?)

* Chronograph both barrels to see if they are producing MV's in the same range. If there is a discrepancy it could be due to different bore sizes and/or freebore, but knowing this will help with deciding on your next move if it is still x-firing.

If the problem persists, perhaps you could report back on the bore and chronograph readings? The issues involved are far too complex to canvass here, however you could read Chapter 10 in Graeme's book for an outine of some of the problems he has had to deal with in achieving regulation.

One final thought. It can't be just assumed that if you seat the bullet to the same overall cartridge length as original rounds that everything will be "hunky dory"! As a last resort, you should try different bullet seating depths.