How do you slug a barrel

lorne19

lorne19

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I would like to get into reloading, and want to reload 7.62x54r for my Mosin Nagant. From what I've been reading the first thing I need to do is slug the barrel to determine the bore diameter. So how do you do that?
 
Oil bore real well, using dowel, rod of some kind drive a pure lead slug, either an egg sinker or oversize pure lead bullet down bore and out the other end, measure slug, get or make bullets .001 or .002" over.
 
Pure lead bullet or round ball of .32cal. or larger, larger soft bullets will work as well, because the excess lead will just flow to the back when pressed. Fishing egg sinker is still prolly the best.
 
I usually slug the muzzle, the throat, and also push one right through. If you measure them all, you can compare and see if there is muzzle wear [most often from too vigorous cleaning] throat wear, or if there is a "tight" spot somewhere in the length of the bore.
Regards, Eagleye.
 
I had neither .32cals or egg sinkers. I drilled out the base of a cast 308 bullet and drove a tappered pin into it to expand it. I removed the pin and slugged the barrel as normal.
 
Slugging a barrel video

I came across this video recently. Quite an innovative way if you ask me!


Part 1:
http://www.youtube.com/watch?v=KuNoo4m6jso

Part 2:
http://www.youtube.com/watch?v=qPHypjU5alQ

How does one slug throat? Muzzle I guess is the same as putting it into the muzzle and then knocking it all the way through right?
 
Mosin's tend not to have varying barrel dimensions the way Lee-Enfields do. Doesn't hurt to slug it anyway though.
"...using dowel..." Don't use a wooden dowel. Breaks and gets stuck in the barrel too easily. Use a 1/4" brass rod(bar stock) and a plastic mallet. A .30 calibre cast bullet or lead fishing sinker will work.
"...How does one slug throat?..." You don't slug the throat or the muzzle. There are guages, but mostly for .30 calibre barrels.
 
lorne19 said:
What caliber ball should I use to slug a Mosin nagant bore.
Click to expand...

00 Buck

You will likely be surprised at the groove diameter. On mine the bore diameter was .3015" and the groove diameter was .315". I've read that the Russians deliberately cut the groove deeper than the theoretical .3115" so that in extreme cold weather, as the barrel shrank from the cold, the bullets wouldn't be bottoming tightly in the grooves and spiking pressure. Not sure if that's true but seems reasonable.
 
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