cast boolit questions for the .45-70

[cudatruck]

Ok, where to start... i have starline once fired cases (in my rifle) they measure only .458 inside the case mouth. were my loads too light to fully expand the brass? can my rifle chamber be that tight? I have some cast 465 gr sized to .458 i think from oregon trail they measure about .456 and fit nicely into the brass. I bought some hunters supply from midway 405 gr sized .459 they measure about .457-.458 and will not start into brass i would have to expand. Also these hunter supply bullets vary GREATLY in weight! none are 405. most are 391-392 gr. these are plain base, i don't think they are desgined for GC. I have a couple of samples from a member here they measure .458 and again won't start into fired brass. Do I need to get a sizing die to bring them down to .457? .458 and expand brass? load a couple really hot to check brass expansion? what's up with the inconsistent weights? None of the bullets i have weigh what they are supposed to, is this common? how much expansion should be normal on the case from firing? any advice is appreciated, thanks, Mike.

[Hairy Chest]

Ok, where to start... i have starline once fired cases (in my rifle) they measure only .458 inside the case mouth. were my loads too light to fully expand the brass? can my rifle chamber be that tight? I have some cast 465 gr sized to .458 i think from oregon trail they measure about .456 and fit nicely into the brass. I bought some hunters supply from midway 405 gr sized .459 they measure about .457-.458 and will not start into brass i would have to expand. Also these hunter supply bullets vary GREATLY in weight! none are 405. most are 391-392 gr. these are plain base, i don't think they are desgined for GC. I have a couple of samples from a member here they measure .458 and again won't start into fired brass. Do I need to get a sizing die to bring them down to .457? .458 and expand brass? load a couple really hot to check brass expansion? what's up with the inconsistent weights? None of the bullets i have weigh what they are supposed to, is this common? how much expansion should be normal on the case from firing? any advice is appreciated, thanks, Mike.

My cases are also .459 after firing.  So what does that mean for people who say 'size and shoot them .460?'  I size them .459.  Then they go through the .458 bore.  Size and expand them normally.  Weight variation for big bullets isn't so important.  But I get .5 grain variation with 4-cavity LBT molds.  I heat them in the corner and when the lube smokes, we are supposed to give it time.  I give it 20 seconds after smoking starts.  The first bullet is always good.  Some fool with air cooling.  I like to drop them in a 5-gal bucket of water. 

So what I'm recommending is a good LBT mold.  You will make great bullets fast and you can push them to jacketed bullet velocities.  For high speed bottleneck cartridges, you need to slow them down.  But they will be just as accurate as jacketed.  What is velocity for?  If it is for expansion, you can make a cast bullet with a nose so soft you can deform it in the seating die. 

For 45-70 and LFN bullet is your best option.  The big bullets have a large meplat which kills as good or better than an expanded jacketed round, but with the big bullet you also get penetration.   


 

[gcrank1]

Yes, bullet weights vary with the alloy used, pure lead being the heaviest.
If those cases were crimped with the loads you fired then there can be some 'residual crimp' left on them which will prevent you from getting a true fit. Take a belling die and bump it back to straight, or slightly belled and try your bullets again. Short a belling die use a largish size round backed needle-nose pliers inserted and rotated to roll any crimp back out.

[Veral]

  For redearship information.  This question is seaking a way to find what chamber diameter is so as to get a bullet diameter which provides a close chamber fit.  The purpose of a close chamber fit on 45-70.s and almost all lever gun rifles is to prevent the bullet from tippping on takeoff. 

Perhaps the simplest way for you to determine what the chamber diameter is would be to drive an expanded bullet into the chamber until it contacts the rifling.  Use any 45 caliber cast bullet which isn't hard lead, hit it on the end with a hammer or squeeze endwise in a vise till it expands a few thousandths larger than a loaded round.    You'll then be able to measure the difference between  case neck diameter of the loaded round and your slug.  Get a bullet which makes your brass fill the chamber within .002.