500 grs is probably a bit much for 22" twist. 350 should work fine and be even better on your shoulder. 

Dave, those numbers do not seem to be consistent with what we did shooting 550 grs 45's to 1000 yards in 16" twist. But they were going about 300 fps faster.

dave, you might do it in a 45/70 rifle with black, but you would have to load from the muzzle and use more than a casefull of powder.
this was done by some long range target shooters in the day, but not really suited to hunting.
regarding stability, reading has suggested different requirements for short and long range.
308 match loads are reported to lose 25% of their spin at 1000 yds. slower bullets will lose more due to longer flight time.
100 and 200 yds do not present this problem.
talking to a br for score shooter the other day revealed that some 30 br shooters are getting round holes in the targets, and sideways bullet profiles in the backing strip.
that is taking the ragged edge of stability to the extreme!
keep safe,
bruce.

scheutzenmeister,
in a previous life I used to load a 400 gn bullet to 2050 fps with 4198 in a marlin 95 (very light rifle) for a certain application.
it was a silly idea .
keep safe,
bruce.

Thanks for all the comments - I'll be shooting both BP and perhaps some smokeless 4759 as that powder seems to actually have a lower pressure curve than BP at the same velocity.  I am NOT pushing for high velocities - I like soft recoil 

Dave, thank you for all the info, but I don't understand.  You said Sg "should NOT" be less than 1.4, which sounds almost like the bigger Sg is the better?  Yet,  the 405 grain bullet has the highest Sg of 2.67 with the 500 grain only 1.84.  Can you elaborate on that please?

Ya'll mention "shooting BP" - How much different will the bullet behave with BP vs the 4759 I mentioned?  I know BP will cause the bullet base to obliterate (not right word, but to expand to fill rifling grooves) and best to use a bullet sized to bore (not groove) for BP, while smokeless best to use a bullet closer to groove diameter.

Thanks to all for comments - and I would "like" to stay with a lighter bullet if possible for reduced recoil and increased velocity at same perceived recoil.

Ken H>

Thanks Dave - I think your answer just now gives me the answer to the question I asked over on the "Gunsmithing Single Shot Rifles" forum.  I'll stay with the 22 twist barrel and order the 500 grain Lee mold - while Lee isn't the best mold I"m sure, I do expect it will do just fine for hunting accuracy..... and they are cheap! 

I really appreciate ya'll for providing me with many hours of good reading on these forums..... and learning.

Ken H>

I shoot a 350 grain Lyman bullet in my Pacific. Fifty grains BP and a wad. Never shot a deer with it but has plenty of power.  Shot some decent OH targets with it at two hundred yards.  Deer not safe. 

I won't have a Lee mold of any kind. Junk.   

            Joe.