NitroX

As Dugaboy said and something I forgot to say but should have.

"You did not say if the barrels are shooting wide, or crossing.
THIS BIT IS VERY IMPORTANT "If they are shooting crossed, and high, which is what I suspect,
they need speeding up a little to get less barrel time! THIS IS LIKELY TO BRING THE BARRELS INTO A
TIGHTER GROUP, AND LOWER ............"

I also agree with Dugaboy that I think you need a little more powder at least as the first thing to change
- BARREL TIME IS VITALLY IMPORTANT IN DOUBLE RIFLES

Finally, When shooting, Shoot one shot from one barrel and look where it goes BUT
WITHOUT CHANGING YOUR SHOOTING POSITION BEFORE you fire the other barrel.
This will let you know if they are crossing.

Also Do as Dugaboy says - shoot 4 shot groups, rt, lft, rt, lft, for four shot composite groups.
You do get a much better idea of what the gun is doing with 4 shot groups.

Chronygraphing - make sure you write down each barrel velocity - just in case down the track
when trying to problem solve you will know that both barrels shoot approx the same velocity
(less than 100fps difference).

Finally, don't dispair - it takes a while and paitence. Of the 20 - 25+ double rifles I've worked up
loads in over the last 5 years, only 1 of then didn't shoot and that was because of a loose rib !!!
Therefore percentages are on your side !!!

Good luck and email or call me if you need.

500 Nitro

DUGABOY1 - with suggestions like you wrote, I think you are up with the experts.