Complicated Mosin question about cast bullets

[Tokarev]

I own one Mosin carbine and several SVT-40 rifles. Since I bought them, I tried not to shoot bimetal or steel-core ammo. That is pretty hard in Canada, as there is shortage of 7.62x54R ammo. That of course hinted at handloading.
First of all I bought a couple of crates of surplus ammo and a box of Hornady 308 bullets, which I was going to use in my 308 rifle and also try in a Mosin and SVT. To much of my uneducated surprise, the 150 grain 308 bullets had to be seated with a huge jump. The OAL of a cartridge loaded .015" from the lands would be such as the bullet would not even be touching the case mouth.
Then someone who I trust explained to me, that the throats in Russian military rifles were made so deep in order to compensate for any possibility of ordnance factories delivering defective ammo to the theatre. If the bullets were sat way too far out, the rifles with deep throats would still shoot, where anything shallow could blow up or refuse to close the bolts. The chambers were desgined with that in mind and seating the bullets close to the lands could produce excessive pressure and result in a kaboom. Are you scared? :???: I am! :(
Finally I decided to abandon jacketed bullets and start casting for Mosin. The SVTs I was told would not like lead slugs as their gas ports would lead up real quick.
The lead bullets recommended to me would be the Lee 200 grain 309 diameter. These are very long bullets, that will end up being seated closer to the lands. Would that be Okay from pressure perspective? That should, as the pressures with lead are lower than with jacketed ammo I thinks. What do you think?

[jonk]

Well except for some of the finns, most mosins use .311 (nominal) diamater bullets. So the 309 lee would be rather undersized, would probably perform poorly, and you'd get leading. Slug your bore. I've seen these measure anywhere from .308 (finn M28) to .317!

If you are anywhere near .311, the Lyman 314299 is a very good choice.

Long throats in military guns are common. I've yet to see a Mosin though that wouldn't close on a factory or surplus round, so I don't think there are any with throats so short that it would cause trouble. Seating close to the lands (.015 off as you suggest) shouldn't cause issue, but it will have to be off that much for each individual gun. And be aware that they might not feed through the mag. But unless you are TOUCHING the lands and using max charges, there is no reason to be scared; I doubt you could blow a Mosin if you tried, short of doing something REALLY dumb like filling the case with bullseye or something.

All this said... some of my better Mosins shoot .308 jacketed just fine. No reason to abandon jacketed if you want to try it, just get some proper diameter bullets. The Hornady .312 150 gr or Sierra .311 174 gr do well for me.

[NuJudge]

I've shot a good many cast bullets in my SVT. I have not noticed any Lead on my piston or cylinder. I don't shoot corrosive in my SVT, so I don't tear it down after every shooting session, and at various times I shoot Lead bullet and at others Jacketed, so the Lead may be blown off by the gasses from jacketed bullets.

I would not want cast bullets for an SVT to have the bullet thrust into the lands. I would be worried about slam-fires or out-of-battery explosions. If you did not encounter those, you might get doubling.

For manually-operated rifles, I prefer my bullets being thrust into the lands at least a little bit. That way, the lands support the bullet during the early stages of firing.

CDD

[JIMinPHX]

Don't be surprised if the barrel slugs around .3140" or even .3145". Some of them are pretty sloppy.

[Lead melter]

Ya might be best to leave the .309 alone for the M-N and get the Lee C312-185-R or, if you can find a good one, a Lyman 314299. Either of those can be sized down to .308 or .309 and the Lee can be "beagled" up to go about .315. Both shoot really well in my 3 Moisins.

[Ricochet]

That's not sloppy in the sense of carelessness. They made them that way on purpose. It's been a common European practice from the blackpowder days to make barrels with groove diameters bigger than the bullet diameter. Makes it very tolerant of production variations in bullet diameter, dirt, oil, ice and rust in the bore. Doesn't affect practical accuracy. These aren't intended to be benchrest rifles.

Don't worry that your Mosin is going to kaboom because of a slight error in bullet seating depth. These are strong rifles, likely as strong as any military bolt action issued, the throats are long, and they designed in plenty of margin for error.

There's also no cause for concern about the well-being of your rifle shooting steel cored, jacketed, or bimetal jacketed bullets. Or cases. There may be fire hazard from sparks struck on flinty rocks, which is why ranges in dry areas tend to ban this ammo. Won't hurt your rifle in any way.

[JIMinPHX]

I'll second what Ricochet said about those things being strong. He's not joking there. Those things are built like a brick.

[Tokarev]

My bore slugs exactly 7.62 at the muzzle. This is grove diameter, not to the lands.

[Larry Gibson]

Tokarev

Sympathise with your use of the metric system but most advise on bullet diameter and groove diameter you'll get here is going to be in inches. A metric 7.62 is .308" to us but .310-.312" to COM-BLOC nations. The odds are your MN and SVT-40 rifles are going to shoot much better with .311-.312" jacketed bullets ranther than .308" jacketed bullets. There are acceptions but not many, especially if your rifles are Russion or Chinese made.

As to cast bullets the MN is very cast bullet friendly if the bore is good just like most rifles. Don't worry about the gas system of your SVT-40 getting clogged up. That is a persistant myth. It is based on one exception that has been in print for years. Of course there are exceptions but the are based on individual rifles not models. If you use a good alloy with a good, well fitted GC cast bullet using a proper lube over an appropriate powder you will find accuracy and functioning to be fine with your SVT-40. Just don't expect either the SVT or the MN to shoot at the ballistic level with cast that they do with jacketed bullets.

Check out this recent thread of mine using cast bullets in a Finn M39 MN. The Lee C312-185 cast bullet will perform close to the same as the group buy 311291 (I now call it a 314291). As you can see I didn't do anything "special" to get that kind of accuracy with cast bullets. I used a good well cast bullet (they were only visually inspected for defects and not weighed or sorted by any means) of an appropriate alloy, a good lube was used (Javelina) and they were GC'd and sized to that rifles maximum allowable size to allow chambering. I used an appropriate medium burning powder (4895) and used a dacron filler over it for consistent ignition. I selected a known load for this bullet weight that also would produce the appropriate pressure level in a velocity range to promote excellent accuracy and it indeed did. I'd bet this load would function you SVT-40 also and be accurate in your MNs.

http://castboolits.gunloads.com/showthread.php?t=45358

Very good success with cast bullets can be had just by sticking to the basics as I did with this load. Good luck.

Larry Gibson

[Tokarev]

I dunno, 7.62mm is 0.300" on my caliper.

[Ricochet]

And I guarantee that is not the groove diameter of your bore at the muzzle. You're measuring it incorrectly.

[Larry Gibson]

I dunno, 7.62mm is 0.300" on my caliper.

Yes, that is 0.300 on our calipers. Problem is we don't know what "calipers" the Russians used! Also reread Ricochet's posts and realize there are manufacturing tolerances. I've slugged and measured a lot of MNs over the years and most of them are not 7.62 by our standards. They run from .310 upwards of .316" groove depths as mentioned with most in the .312-.314' range. Some of the tighter bores (not groove depth) will do ok with .308 bullets but most will not.

We're just telling you what we've found over the years. I was not a fan of any MN for many years (even though I had two MN war trophies) because neither my MNs would shoot .308 jacketed bullets or my .309 cast bullets better than improved cylinder. All the manuals listed .308 bullets to use so I/we assumed that was what was needed. Then one day a gunstore clerk gave me a damaged box of Hornady .312" bullets. I though I'd try them in my MN and my 91/28 went from not hitting the target to 2-3" groups at 100 yards. I then tried some .312 sized cast bullets and the same thing happened....excellent results! Now I am not the only one who has discovered this by trial and error on this forum or else where. If you want to find out yourself then by all means, "trial and error". We are just trying to save you the "trial and errors" we madel. Like all advise you can take it or leave it.

Larry Gibson

[Tokarev]

And sure as hell you are right! I was confusing myself measuring the diameter between the lands. This BBL measures .315" between the groves.
But that creates a whole new opportunity: I can paper patch the 309 bullet.

[JIMinPHX]

You really want to slug it near the chamber, not the muzzle if possible.

[Tokarev]

How do I do that with a rifle? I have been casting for the antique revolvers since I remember myself, but the rifles have a chamber in place of a forcing cone, which I measure with a caliper which I modified by grinding off the OD lips. Do I just hammer a slightly oversize lead rod into the bore, pull it out and measure?

[jonk]

Well you can either hammer a slug all the way through the bore, or yes, just push it in a few inches, then tap out.

Now PAPER PATCHING your Lee 309 is surely an option. If your grooves measure .315 then a double wrap of paper and sized to .316 would probably do well.

[Larry Gibson]

Tokarev

Do a search on how to do a swaged lead slugging of the throat. One member here has a good method but I don't remember who.

Also, most COM-BLOC chambers have a tapered throat to the leade instead of cylindrical. Many of their throats just taper from the outside of the chamber case neck mouth to the start of the leade. It is usually a long throat so that the "heavy Ball Type D" can be used along with the "Light Ball L" loads.

I use a cast bullet sized the same as the inside diameter of a well fire formed case neck. For example; in my SAKO Finn M39 I size the bullets .312" and they just chamber. If I use .314 bullets they are really hard to chamber. In my M91/30 sniper I can use the .314" sized bullet.

Interestingly pressure tests show no difference in pressure between the .312 and .314" bullets in the M39. These are not crimped loads and there is no "pinching on the bullets from that. The .314" bullets, even though a really tight fit, seem to just slide straight out into the throat without raising pressures.

Bottom line is that you can use as large a bullet that will alow chambering. PP'ing may be a good way to go. Several here PP for their oversize .303s with good success. With your rifle I would definately try the 150 gr Hornady .312" SP for a jacketed bullet. For cast try the 314299 or the C312-185. Either at a minimum of .314" sizing should do well.

Larry Gibson

[yodar]

Ya might be best to leave the .309 alone for the M-N and get the Lee C312-185-R or, if you can find a good one, a Lyman 314299. Either of those can be sized down to .308 or .309 and the Lee can be "beagled" up to go about .315. Both shoot really well in my 3 Moisins.

I have Mosin Nagants, Enfields and SKS and the Enfields and Ruskies DO need the bigger bullet

Adding a scoop of magnum shot (or a 35 mm film can ful0 to the wheelweight melt enhances the hardness (additional antimony for hardness and arsenic and allows for heat treatment) gets me a sizable percentage of the bullets dropping to .313 - .315 just measure them and take the big 'uns for your ragged out ruskies ;>)

by Gawd dont beagle that mold!

yodar