Anyway to find what diameter bullet to use?

[Mosin-Marauder]

WITHOUT slugging the barrel. I'm not really to keen on forcing a hunk of metal down my bore. So, is there an alternative to find the best diameter to use for my 7.62x54R rounds for my 91/30?

[green_MTman]

to the best of my knowledge the 7.62-54 russian is a .311" diameter cartridge.it might be good to double check.

i dont know any way to know for sure without sluging the bore.you could try shooting a .308 size bullet down and if accuracy is real poor i would guess you have a .311" barrel

you could also try to chamber a .311" unprimed dud round and seated well before the rifling.if it wont chamber easily that may mean its a .308 barrel

[Blindstitch]

You could take it to someone and have them slug the bore. Or just bite the bullet and slug it.

http://youtu.be/ErFaJlUVs1Y

[jepp2]

Cerrosafe Chamber casting alloy link could be an option.

[green_MTman]

wikipedia says it fires a 7.92mm .312" bullet so that means you will have to slug it.bad accuracy from a 308 could mean 311 or 312.

you must slug the bore at this point

[SpringOWeiler]

you can take out your calipers and measure the groves at the muzzle. Average them out.

[FrankenMauser]

you can take out your calipers and measure the groves at the muzzle. Average them out.

That'll get you in the ballpark, unless the muzzle is eroded, counterbored, or tapered. In those cases, it could be way off (or out of reach).


The throat is more important than the muzzle. Just grease it up and slug it.

[Mosin-Marauder]

I just don't want to damage the rifling. The Surplus I'm shooting now seems to be doing pretty well. I'll measure them all and get an average.

Also, my bore is counterbored, that isn't bad, is it?

[Gadawg88]

If I'm not mistaken, a hunk of metal getting forced down the bore is what happens every time you pull the trigger. Use a brass rod or wood dowel.

[Jimro]

Well, if you know the length of the bore and the mass of the rifle and have a VERY accurate scale, you could measure the mass of the rifle, then fill the bore with oil, and measure the mass of the bore with oil to get the volumetric mass of the oil, and use that with the length of the bore to calculate the mean bore diameter.

Or possibly use X-rays...

Cheaper and easier just to slug it.

Jimro

[William T. Watts]

Don't really understand why slugging a barrel that could be 100 years old is a big thing, if you don't want to use lead then Cerrosafe is a viable substitute. Run a patched rod down thru the action stop about 1" from the muzzle mix your Cerrosafe pour it down the muzzle, use the rod to force the Cerrosafe cast out of the bore when hardened and measure. Usually Cerrosafe is used to make chamber casts, Cerrosafe will shrink a tiny bit when hardened that will help facilitate removal from the bore!! I have used it and it's basically fool proof, just follow directions.. William

[FrankenMauser]

Also, my bore is counterbored, that isn't bad, is it?

It just means that the bore was eroded or measurably damaged from cleaning, when it went in to be rearsenaled, at some point. To remove the damage and save the barrel, they counterbored it.

A good counterbore job will greatly improve the rifle (from its damaged condition), and return it to performing respectably.
A bad counterbore job, or counterbore job on a barrel with abnormal wear, can completely ruin accuracy. (Or just fail to improve it.)

---

Are you reloading, yet?
I may have some bullet I can send you, to see how they fit your throat.

[Mosin-Marauder]

My dad is ordering me some dies and a shell holder this week. I'm going to go to my Local Gun Shop to see if they have .30 lead balls so I can slug the barrel. (I was told it wouldn't damage my rifling because lead is softer than steel).

What kind of bullets are they?

[wogpotter]

Slugging should be done with very, very well lubed soft lead.

Did I mention well lubed?

That should do way less harm than firing a single round of jacketed ammo. Because of that I think you're over engineering a simple process. Use 3" long sections of alloy or brass rod or even wood dowel just below bore size & you should be fine.

[tangolima]

Originally Posted by Mosin-Marauder

My dad is ordering me some dies and a shell holder this week. I'm going to go to my Local Gun Shop to see if they have .30 lead balls so I can slug the barrel. (I was told it wouldn't damage my rifling because lead is softer than steel).

What kind of bullets are they?

You need a bigger than .30 lead ball to slug a mosin. You pay more if you go to a gun shop.

Cut open a 00 shotgun shell and use the lead shots. Another choice is lead sinker for fishing.

Use a micrometer to measure. A caliper is better than nothing, but is not good enough.

-TL

[Mosin-Marauder]

A .313 lead ball will be plenty big enough. IV8888 did a video where he slugged an M39 with a .311 diameter ball.
A .320-.330 lead ball will be too much to over what I'm willing to slug.

[tangolima]

A mosin bore could be as loose as .313". It is soft lead. Your mosin has gone through way worse things than being slugged, believe me.

However your rifle is counter bored at the muzzle. I wonder how you can pound that slug into the bore. Haven't dealt with that before.

-TL

[Mosin-Marauder]

I would think the same way, it would just be a little looser on on end .

[Mike / Tx]

Slugging is SO much faster and easier, but, if you want it as good as it gets, read through and follow the directions in this link,
This-is-how-I-do-a-pound-cast

This will give you ALL of the information you need for YOUR rifle and will allow you to find and purchase the right bullets or molds for it.

There are a ton of things you COULD do and still come up short but this will get you right where you need to be the first time and your done.

Oh and as for driving a lead slug down the lubed barrel a whack at a time, well it has nothing over firing just one jacketed round through it at 2800fps or so.

Find you a brass rod, nix the wooden dowel idea forgettaboutit, and do it right and your done.

[jeager106]

Quality control was never a strong suit for the Russians when making guns or ammo.
I've taken apart several rounds of that cailber and found a variation of 5 grains in the power wieght, & 7 grains in bullet wieght.
Mosin bores vary widely from .308 to .313, most do well enough for what the rifle is with .311 bullets.

[Mosin-Marauder]

Mike, I'm not too sure about whatever you just showed me... I only have 4 of the things on that list.

[5whiskey]

First off, as others have said, you will do no damage at all by slugging your bore with pure lead so long as you use a wooden dowel or brass rod to punch it through. If you happen to get a slug that's a little too small you can always give it a gentle tap with a brass mallet on a firm table to oblong it. If it's only a few thousands smaller then a VERY gentle tap will do. Likewise, I have also used slugs that are too big by rolling them on a firm table on one axis with some significant pressure. This will make the slug more narrow on that axis, and not as much work to tap through the bore.

The bore of an accurate rifle is truly a work of art, and I would probably use extreme caution slugging a bore if I had a bench rifle (wouldn't be needed at that point, but that's neither here nor there). With that being said, I would not hesitate to slug the bore of a .3moa rifle if I needed to get the proper size projectile, but I would be cautious. With your Mosin... I wouldn't stress it. Just don't try pounding an abrasive steel slug through (good luck with that anyway) and you'll be good.

[FrankenMauser]

A .30 caliber lead round ball won't give you enough of an impression to be useful, even if you flatten it a bit first.
And, even if you get a larger size... you'll be stuck with 99 other lead round balls that are of no real use.

PM me your address. I'll mail you some pure lead that's appropriate for slugging purposes. (Either pure lead wire or pure lead .32 caliber bullets [.314-.318"].)
There's no point in wasting money on round balls that you won't use again.

That way you'll have a couple of days to research "impact slugging" to know how to get some measurements for your throat, as well. It isn't a necessity, but it's good information to have.

[chiefr]

Slugging is simple. There are plenty of You Tube videos out there to show you how.

I use a conical lead plastic worm fishing sinkers exclusively. They are pointed thus easy to start and leave plenty of rifling to mike.

Conical Lead is superior to round balls.

[tangolima]

That's the sort of sinker I have been using. I'll cut it short a bit for smaller calibers.

-TL