I reload for the 44 colt and an early 44/40. If you switch to a hollow based bullet you will get a lot better results. When you fire the rnd, the gas causes the base of the bullet to expand or bump up and seal the bore and contact the rifling. I use a rapine mold #RAP430211 it cast a 211 gr. FN hollow base bullet. It comes out of the mold about 430, i size mine down to .428, i use this bullet in both the 44 colt and 44/40. I load them with BP and really have had excellent results. The 44 colt I am firing from is an early kirst konversion, when they made it in 6 shot 44 colt. It is on a uberti 58 remmington, the bore diameter is about 451 and the bullets bump up and work nicely. If i use a solid base bullet the rnds will key hole because they are tumbling in the barrel. I reload 38lc with a hollow base bullet also for a 51 conversion that I shoot.This is common with the old conversions, in 44 and 38 lc. The early ammunition was loaded with hollow base lead bullets because of this. In todays newly made repos chambered in 44 colt like the open tops and richard mason conversion being offered by cimmirron the barrels are 429. So it is not a problem. You could also try a heeled bullet, but molds for these are getting harder to find. I think buffalo bullets is selling these already cast and lubed if you want to give them a try and see how they work in your rifle