You most certainly can use those 200 gr round nose in 45 colt. You will need to decide what type of crimp to use. I stay with the traditional roll crimp even though there probably is not a crimp groove in that type of bullet. I roll the crimp ever so slightly into the bullet at whatever seating depth I set the bullet. Accuracy does not seem to suffer at all. Others will say to go with a taper crimp. The most important aspect is to make sure your sizing die is correct for .452 bullets so that the case neck tension is sufficient to keep the bullet in place. After loading a few rounds, push the bullet against a firm surface to see if it will move deeper into the case. I typically load 6.0 gr Bullseye or AA#2, 7.0 gr W231 or HP38, or 8.0-8.5 gr Unique with a 200 gr semi-wadcutter, also a .45 acp bullet. Accuracy is great, and these loads should work well for the same weight in a round nose bullet.
