I happen to have a lot of H4831.So, am thinking of using it in my 38-55. I'm thinking of starting around 40 grains behind a 330 grain bullet. What say you?

Ken Waters used H4831 in his 45-70 lead bullets loads with claimed success, not me though nor will I ever in any rifle designed for low pressure/black powder loads. Smokeless powder is one bad mother when misused and there too many correct powders out there listed in too many reloading manuals that will work correctly to venture off track just because one has a surplus. Stay safe and load a proper powder, good luck. 

No, way too slow.

I tried Waters’ 4831 loads in my .45-70 Garrett Arms Sharps Carbine back in the 80s.  His claim that it burned at a different rate in straight large bore cases vs “overbore” bottlenecked cases appeared to be valid.  The gun shot very accurately at apparent low pressure with 405-gr bullets, as long as I blew the (many) unburnt granules of powder out of the barrel between shots.

Waters apparently discovered this peculiarity on his own; I can’t recall any loading manual mentioning such a load.  And, as far as I know, he never tried, or at least never published such a load in any other straight case.  Whether it would scale down to a smaller straight case with a lighter bullet would have to be determined by experimentation.

The loads were kind of an artifact of their time: practical as long as you could get a shopping bag full of surplus 4831 for ten bucks, or a pound can of the stuff for $2.50 or so.  With powder prices as they were even ten years ago (not to mention now), there are better uses for 4831 than blowing 1/4 of the load out onto the ground with every firing.

I’ve had good accuracy in the .38-55 in Highwalls with 21 gr of 3031.  This is definitely an underload, compared to the usual hunting-load recommendations, but all the powder burns and pressures appear low.  This is just what I’ve found; YMMV; not a recommendation; some patients experience hives, soreness, reddening; etc.

I got a 60 pound keg of it for $20. What else would I use it in? I loaded it in my 45-70 and got the same results you did. Good accuracy, dirty bore. But I swab between BP loads any way, why not swab between smokeless loads? I tried some in an 8MM Mauser with lead bullets and it burned clean with the bottle neck case.