At the risk of sounding like a noob to the BP game (which I am) I need some more help. The rifle is an 1884 trapdoor with a new green mountain barrel screwed into the action. Ok, so I cast my Lee .459" 525 gr bullets and load an empty .45-70 case for OAL testing and chamber fit. The case is full length sized and trimmed to correct length. No primer or powder. I have a hell of a time chambering the round. I basically force it into the chamber and then knock it out with a brass rod. I see two scrape marks right where the two rings around the bullet are but on the outside of the case. So this tells me my bullets are too big for the chamber. I figure I need to size the bullets down to fit the chamber. Everything I have read from the ventrino (or what ever his name is) deity says I don't need to size my bullets because of barrel fit and all that voodoo. I can't be the first guy to run into this problem. I don't own a bullet sizer nor ever used one. what dimension do I size them to? What bullet sizer do I use? Would it be easier to use jacketed bullets. This is just a deer rifle, no competition nor do I really care about being historically correct. Should I make the jump to the bullet sizer? or maybe going to a different bullet mold? So many questions.

Lee make a push through bullet sizer,doesn't cost much.
Have you slugged the bore with a pure lead slug to find out what size you throat is?
Also drive one through the barrel.

Okay the way I understand what you are saying is that the case shows marks where the bearing bands (rings as you called them) of the bullet where it's seated in the case. If so and there are no other marks on the bullet outside the case more then likely the throat is okay, it's just that neck area of chamber is tight for the .459 diameter bullet you seated. I'd slug the groove and see what it is first. The other poster said to slug the bore to get the throat size. He should have said do a throat cast as the bore is hole they drill then hone in the barrel before they rifle it. It will be quite small in comparison to the groove and throat diameter. If you find your groove much smaller then the .459 you're sizing your bullet you may be okay.

I believe Mike Venturino was referring to loading for an original trapdoor with the original barrel. They may have a more generous chamber, throat, bore, and groove then your new barrel.

try running your loaded dummy round through the sizing die with the decapping assembly out, remember to lube it well and see if it fits then.

Running a loaded case through my sizer die? I wonder about crimp on the bullet and pressures. Just a thought.

Best to slug the barrel to see if the groove depth is .457 or larger. If .457 (a very good posibility) then get the Lee .457 push through sizer. The directions come with it and it is simple to use in the reloading press. If the cast bullets you're using are already lubed you won't need to relube them with the lube that comes with the sizer. Just size them .457 and load them.

If the groove depth of your rifle is .458 or larger then the chamber was cut with a very minimal reamer or perhaps not "finish" reamed. A gunsmith can use a standard 45-70 reamer to finish ream the chamber but the barrel will have to be pulled to do it.

You also don't say what cases you are using. Winchester cases are the thinnest, especially at the bullet end. If not using those you might try them.

The problem there is with that tight chamber you may not be able to chamber rounds loaded with .458 jacketed bullets (the most common size for jacketed bullets). Thus finish reaming the chamber may be your only real option.

Larry Gibson

quote:

Originally posted by 45otto:
Running a loaded case through my sizer die? I wonder about crimp on the bullet and pressures. Just a thought.

Run a few LOADED rounds into the SIZER if you have an open top sizer die. Run them in only deep enough to get them to chamber. This will size the bullet as the case is sized.

38-55 shooters have to do this often with rifles that have groove depths of .380 to .382.