Slugging the barrel

[Ace Lungger]

 :)howdy Pards,
I want to slug my 45-70, I poured some pure lead 457 round balls, I set one on top of the muzzel and it covers the whole inside, so why couldn't I use those to slug my barrel?
I would be deeply greatfull for any and all help!
Thanks ACE

[Pettifogger]

The nominal barrel diameter for a .45-70 is .458.  If your round ball actually mikes .457, it is to small to slug the barrel.

[Driftwood Johnson]

Howdy

You want to start out with something slightly over sized. The slug gets deformed as it first enters the rifling. The lead does not so much get cut, it reforms and mooshes around to conform to the shape of the rifling. You want the slug to completely fill the rilfing grooves. If the slug starts out .001 or .002 or more smaller in diameter than the rifling grooves, you may not completely fill the grooves, so any measurement you take from the slug is suspect. The only way to be sure your slug completely filled the grooves is to look for drag marks on the high spots of the slug. You will see drag marks on the low spots of the slug too, corresponding to the lands of the rifling, but the drag marks on the high spots, corresponding to the rifling grooves, are what are important. The drag marks will be fine lines, running the length of the slug. If you do not see drag marks, you may not have completely filled the rifling and any measurements you get from that slug are suspect.

It takes a little bit of guesswork choosing the right slug to start with. A .457 ball may or may not distort enough in the barrel to fill up .458 grooves. I have slugged barrels with all kinds of things, the larger the slug is compared to the rifling, the tougher it is to get started.

One trick you might try with your .457 ball is to slightly flatten it with a hammer on a metal plate. Measure the diameter to see if you increased the diameter at all. Just a few thousandths over .458 should be good enough. Then orient the ball so the 'fat' diameter is in contact with the rifling. Flattening the ball a little bit may also give you a slightly flatter bearing surface to place the rod against while you are starting the slug in the bore. The other advantage of flattening the ball is it will make for a longer section in contact with the rifling, which will make measuring easier.

[Ace Lungger]

 :)dj,
  Thanks a bunch Sir! I just want to do this so I will know the correct size my barrel is! I have been told by several people that since i am going to use pure lead in my bullets that you don't have to size them! I picked up a Old Lyman Luber Sizer 45 that looks new, but it isn't, and I am going to use my BP lube in it with a 459 dia sizer. So maybe I don't even need to slug it, but i thought it was a good Idea?
What do you think? Do you slug all your barrels?

I would be great full for any and all advice!
Thanks
ACE

[Sgt. Jake]

     Ace     I do not want to speak for Driftwood,so I wont. I want to know what the diameter s of my barrels are. If I have this correct the lead balls you have are a little small to work. What I have done in a pinch is to put one in a vice and just give it a little squeeze, it will get you where you want to get.       Adios  Sgt. Jake

[Driftwood Johnson]

Thanks a bunch Sir! I just want to do this so I will know the correct size my barrel is! I have been told by several people that since i am going to use pure lead in my bullets that you don't have to size them! I picked up a Old Lyman Luber Sizer 45 that looks new, but it isn't, and I am going to use my BP lube in it with a 459 dia sizer. So maybe I don't even need to slug it, but i thought it was a good Idea?
What do you think? Do you slug all your barrels?

Howdy Again

Just because you are using soft lead bullets does not mean you can get away without sizing them. If they are plainly too large, you have to size them to get them down where they need to be. If they were 4 or 5 thousandths too big you probably could not even get them to chamber.

I size all the bullets I cast, some are cast from pure lead, some from about 25/1 lead/tin.

No, I don't slug all my barrels, but at one time or another I have slugged most of them. It really isn't that hard, just takes a few minutes. Makes choosing a good diameter bullet less guesswork.

[John Taylor]

I probably do more barrel work than most on this sight so I better jump in here. When slugging a barrel I use a ball that will roll down the barrel and then insert a brass rod from each end and bump the ball to expand it. If you hold one rod still and slide the other rod it will bump the ball and fill the grooves to get an accurate measurement.  May need to hammer the ball out with one of the brass rods. You should check the barrel in a few places, some times there will be tight spots and loose spots. When pushing the slug out you may feel tight spots. Always clean the bore first and use a thin lube.  If the barrel is a little tight at the muzzle it is a good thing.  If it is tight at the chamber end and loose at the muzzle it may not shoot well. Sometimes a barrel can be hand lapped to take out tight spots.
  Most shooters use a bullet that is .001" over groove diameter. Any larger and the bullet is deformed to much when being fired. The mold should cast a bullet .002" to .003" over bore size and a sizer used to get it to the size needed. To much sizing deforms the bullet also.