Generally, you're safe using jacketed data with lead bullets. Differences arise when the bearing surface of the bullets are different, but most times, the softness of the lead mitigates a longer bearing surface on a lead bullet. My caution is to not trust cases that fall out as a pressure indicator. In straight walled cases, you can sometimes approach pressures that are double what shoud be put in a gun and they still might fall out. Web expansion measuring is also not good indicator. A chamber that is cut a little loose may give a measure that indicates a high pressure load, but may be way below SAAMI specs. Different brass might also give a false reading. I do look at primers though. They can tell you if you've exceeded pressures, but may not tell you each and every time. My guide is the published data from Hodgden and various powder manufactures since I don't have access to pressure testing equipment. Black Hawks are brutally strong, I push my 45 Colt to 30,000 PSI and feel confident it can take anything that walks, crawls, creeps or flies in the the lower 48. A 300 grainer doesn't have to go that awful fast to cause an inny and outy on a deer with a quartering shot. If you get 1,200 f/s with a 300 grainer and it shoots accurately, I don't think you could ask for anything better. My opinion and my 2 cents worth!
