Just looking for a few opinions on this subject. My 45 Colt Bisley has a bore that measures .451 I have slugged it twice to be sure. The chambers mouths measure .4545 with 2 that go .455. I can push unsized bullits at .454 through the cylinders with very little pressure. I tried some RCBS 270 SAA that I cast and the results where not that great. I had to size them at .452 because that's the sizer I had on hand at the time. I was able to lube some without sizing but have not tried any yet. I also have a .454 sizer on the way. With the bullit sized this much over bore would I run into any problems with pressure spikes or anything else I should know? I would like to work up 2 loads for this gun. One around the 1000 fps mark and the other in the 1250 fps range. I've chrono'd some of the loads I have shot and I am within this range. Thanks.