Help slugging bore

[Patrick L]

I am trying to slug the bore of my 7.7 Arisaka, and I'm having a rough time.

I cleaned the bore and left it oily. I took a swaged .38 wadcutter bullet and usig the flat of my vise hammered and turned it into a little lead cylinder. Using a dowel and then a brass rod, I tapped it thru the bore from the muzzle to the breech. It went through suprisingly easy.

Problem is, the rifling marks are very shallow, and the whole thing seems sort of slanted. When I try to measure it with a 1 inch micrometer, readings are all over. They range from .304 to about .311. It is very difficult to be sure I am spanning groove to groove.

Is there an easier way (or something I'm missing?)

[Down South]

It doesn’t sound like you got a tight fit with the slug you used especially if it was very easy to drive though. The swaged slug you used ma be just a bit too hard too. A fishing sinker may make a better slug to use.

[Patrick L]

I neglected to mention that I did have to drive it into the bore. It did displace a decent "skirt" of lead.

I realize that my initial post may have made it sound like it slipped right through. I did have to tap it.

That said, I will try to dig up an old sinker.

[Papa smurf]

I have been shooting cast boolits for many years.When I first started in the 1960's I took the advice of then an "old timer"who told me to try putting the cast boolit
that I was wanting to use in the muzzle nose first, if it fit real tight it would work.
He felt that suporting the front of the boolit as it went down the bore was the most importent part of finding accuracy,and just use a boolit equal to or just a little larger than the factory would use. This has worked very well for me for many years in many different rifles. I have never slugged a bore (boy o boy this will turn the volume up some)!-----Good shooting---- Papa.

[mooman76]

If I remember right those Ariska bores or at least some of them have a odd style rifling, almost like the polygon style rifling. Also if they have a odd number of rifling it makes it a little more difficult to measure. Look at the rifling, if it is an odd number of riflings, take something like a small strip of aluminum can and wrap it around the bullet and measure that and subtract the aluminum thickness x2.

[docone31]

See, I kinda cheat.
I put a wood dowel in the barrel, pour in some lead with a ladle.
I then push that down through the breech.
Gets me pretty close.
I can also use that as a lap also.

[Patrick L]

In a flash of inspiration, I got a great idea!! I used an unsized bullet. Its still not perfect (it seems to run a bit at an angle) but at least I got a usable slug. My micrometer only reads to three places, but depending on which way I measure I seem to be on either side of .312 (maybe .3115 to .3125 I'm guessing?)

I wonder if I could get one started from the breech, and if the throat would help it start straighter?

[docone31]

A man who cannot be beat, won't be beat.
I would guess to the large side however.

[tcrocker]

A gun smith buddy of mine uses "play dough". No joke. and pushes it through with a dowel.

[docone31]

Why not?
I can see where that would be simple.
Way cool.

[454PB]

Play Dough??? How can you measure Play Dough with a micrometer?

[GrizzLeeBear]

... My micrometer only reads to three places, but depending on which way I measure I seem to be on either side of .312 (maybe .3115 to .3125 I'm guessing?)

In that case I would try a .313 boolit. If it chambers fine, shoot some loads with it and go from there.

[runfiverun]

those arisakas are pretty finicky when it comes to cast.
313 or 314 is probably what it will like and getting for much over 1800 will give you a migrane.
you will want a boolit that is fairly long as your throat will be also.

[The Double D]

You might have better luck slugging the bore if you can find a pure lead 36 cal lead round ball. Dry the bore-no oil. With a plastic mallet drive the ball in the muzzle. Then with a short brass or nylon punch near bore diameter drive the slug in a few inches. You should then be able to push the slug on through the bore. If you can't push the slug on through then use a series of longer and longer brass or nylon rods to drive the slug on through the bore.

Odd number rifling can be measured fairly simply with a dial caliper. Hold the slug between the slack jaws of the calipar and roll the slug several times. Wacth the dial for the measurement that repeats. That is you major diameter.

A couple of nevers.

Never use a wooden dowel to drive anything down the bore of a rifle. The end fibers will split and jam around the object in the bore.

Never pore lead down the bore. Lead will fill any roughness and grip the bore walls and will resist being driven out. I know you can use just a little and will work, but one mans enough is the next mans to much.

Some years ago when I had my shop open, I would get one or two of these a year. Somebody read some where to pour lead in the chamber or bore to make a casting. Then the had to bring it to me to get it out.

The all around best way to slug a bore is with LBT's boreslugs. http://www.lbtmoulds.com/measurebore.shtml