Marshall or anyone, I did try 9.0, 9.5 and 10.5 grains of Universal Clays along with 6.0, 6.3, 6.5 and 7.0 grains of Tite-group with the Mid-Kansas 0.452" 250pb rnfp. 10.0 of univ clays was still most accurate overall with this bullet. I just tried the slip fit of these bullets and your 0.452" 340gc through the cylinder throats of my Ruger Bisley 45 Colt. The mid-kansas bullets seem to require about the same effort to get them through the throats as your bullets do. I also just measured some of the mid-kansas and Beartooth bullets with my 0.0001" micrometer. Both bullets averaged about 0.4523". Perhaps the bullet lube in the grooves caused the micrometer to read the few ten-thousandths over. I was told by the gunsmith who opened up the throats that they should be 0.4525". Apparently the bullets are pretty well matched to the throats but I have no idea what the bore and groove diameters are. I bought this revolver new this last spring. Do you know what dimensions Ruger is using for their 45 Colt barrels? As stated before your 340gc bullets are shooting very well in this gun sized at 0.452" so presumably the problem of inaccuracy with the lighter weight bullets is not due to their diameter. My hunch is that either, as you said, maybe they have air inclusions and so are off balance or I am not getting them to obturate properly at these low velocities (low pressures). Also I understand that shorter bearing surface bullets are not generally as accurate as longer bullets since the longer bullets can span the gap between the throat and forcing cone. When I ordered the Mid-Kansas bullets I asked about trying their "Cowboy" bullet which has a BHN of 11 as apposed to their regular bullet of BHN 16 thinking that at the low velocities I was wanting to work with I might not get full obturation but they still suggested the BHN 16 bullet. Do you think a softer bullet would work better? The Mid-Kansas website indicates that for a cast bullet to properly obturate it needs a pressure of 1422*BHN so if BHN is 16 then pressure to obturate is 1422*16=22750 p.s.i. and if BHN is 11 then psi needed would be 15640 psi. Your bullets at BHN 21 would need 29860 psi. Does this sound right to you? I have no idea what kind of pressure I am likely generating with 10.0 grains of Universal Clays or 6.5 grains of Titegroup behind the 250 grain rnfp, do you? How does one convert from psi to cup? My understanding is that with the Ruger the maximum recommended pressure is 30000 CUP. From the Hodgdon manual it looks like psi is about 15% higher than CUP so 30000 CUP=34500psi. Does that sound about right? So if I wanted 22750 psi to properly obturate a BHN 16 bullet I would need 19780 CUP. So in looking at the Hodgdon manuals load data there are two sections. The low pressure section's loads are for a maximum pressure of 16000 cup and the high pressure section's loads minimums are at 23000 cup and at higher velocities than i want. I want to achieve an accurate load with a 250 grain rnfp at about 700-900 fps. What powders and charges would do this while giving me adequate pressure to properly obturate a BHN 16 bullet? Or should I give up on these BHN 16 bullets and try the BHN 11 bullets? I do not know how much higher I can go over Hodgdon's loads in their low pressure section or how much lower I can go from the data in their high pressure section. What a dilemma. Help please! Thanks for listening to my ramblings, Brian.
