SLUGING BARREL FOR DIAMETER ?

[Buffalow Red]

I drove a hornaday .490 round ball in the muzzel end of my new 45LC Taruas  lightning rifle with a plastic mallet then used ball starter from muzele loader to push it down , then a brass 5/16 rod to push it the rest way & out the chamber . it measures .450 .

? is the first 12" was real tight then the slug free fell to the chamber area the chamber was a little tight but not much . i did it 2 times to be sure , is it normal to be wider at the middle of barrel . i have only shot at close range so far, 25yards,  shooting off hand standing, got holes around 3" circle with sized .452 cast lead bullets.
should i have started slug at chamber, the brass that comes out seems to expand more on one side than the other ,i can barrely tell it looking real close.the action works perfect .mine came with a manuel   & it says not to take rifle apart,but to use aresol cleaners i thought that was odd.
thanks for any advise

[Driftwood Johnson]

Howdy

Well, the grooves should be of a uniform diameter the entire length, but I suspect it isn't all that unusual. On some reproduction Sharps, and perhaps some other large caliber Single Shot rifles, the rifling may be purposely 'choked' .001 or so at the muzzle, but it is not normal with most other rifles. When slugging a barrel, if the slug runs the entire length of the bore, obviously the slug will only squeeze down and record the narrowest diameter. I have a couple of 100 year old lever guns, and their bores are pitted and a little bit tired. When slugged from the muzzle the slug stops meeting resistance and slides through with no effort at all about 6" or so from the chamber. This is typical of old guns, the rifling starts to wear most near the chamber where the heat and pressure are highest.

One trick is to send a slug partway down the barrel from the chamber, mark how far it went, then shove it out again back down towards the chamber. You can chart a very accurate profile of the interior of your barrel this way. But you have to be able to slug from the chamber to use this trick.

Frankly, I wouldn't worry about it too much. If you are getting .450, standard groove diameter for 45 Colt is .451, so your barrel is not 'choked' very much. You really cannot slug from the chamber unless you have straight line access to the chamber. I dunno anything about those rifles, so I cannot advise you.

When you measured your slugs did you see longitudinal drag marks on the high areas left behind by the grooves? You should see drag marks. If not, it is possible that the slug did not completely fill the grooves and it may not be an accurate representation of the diameter of the grooves.

[Buffalow Red]

thanks it seemed like to me to have a good reprzentation of the rifling groves this is a new rifle 200 rounds through it now was very acurate at match last weekend, i still havent been able to shoot paper at long range yet hope to soon. was slugging to see what sizer die size i needed

[Buffalow Red]

so i slugged my new to me marlin 44 mag rifle it came out at .425-.426
what sizer die would be recomened