M-N with Oversize Bore

[centershot]

I have an old M-44 Moisin-Nagant carbine with an oversize bore, it measures .317" OD. I have a Lee 312-185 mold that drops boolits at .314", too small to fill the bore but they shoot well at sub-sonic velocity and make good plinkers/gallery loads. For any type of heavier load I'm relatively sure this boolit would fail miserably so I've been eyeballing the 8mm selections. My question is this - Is sizing down from a nominal .325" to .318-319" going to materially deform the boolit, and can this be done in one pass or do I need 2 separate sizer dies? My alloy is 94-3-3, so around BHN 12, I have a Lyman 450 and a Lee Classic Cast loading press. I'm thinking Lee sizers in the Classic cast would do the job, just concerned about boogering up the boolit.

[krallstar]

What size is the throat. On mine bore is .316 but throat is .314

[gpidaho]

centershot: I have an old M-M with a LARGE bore also. It's .316-.317 and that's not the worse part. The neck portion of the chamber won't allow the use of a bullet any larger than .314+. I powder coat and size to .314 and haven't had any leading problems so you might give P.C. a try and try for the largest bullet that will chamber. Gp

[centershot]

Well now, you gents raise an interesting question! I've not done a pound cast to determine the throat specs, it never occurred to me that it would be smaller than the bore diameter (and just how the heck did they manage to do that anyway????). Looks like it's pound-cast time at the centershot house!

[jugulater]

I have a 1936 Ex-Sniper that shows heavy wear, it slugs .316, but the chamber will accept boolits up to .317. i use the NOE 316299 Boolit in this poor old gun and manage to keep it on a 8" gong at 100 yards most of the time.

my gun appears to be the exception to the rule, but if your gun will accept a .316 boolit i highly recommend the NOE 316299

as for the barrel and chamber differences lets just say the Soviets werent known for quality control...

[gpidaho]

Well, mine is a Polish M39 carbine. I just thought that was the explanation. I use the NOE 314299 powder coated. I don't shoot it much since I scoped the bore. I don't believe it had ever been cleaned before I bought it and once I got it scrubbed out (took several day's on and off) it most likely wasn't worth the effort. It only cost me $100 and it's been fun doing experimental things on it that I wouldn't have tried on a better rifle.Gp

[Bookworm]

I have a 1930 Izzy, the bore slugged at .315. I shoot the NOE 316299 (316-203RN). It drops at 316-317 with air cooled CWW. I size to .316. No leading, even though the bore is pitted.

The problem comes in with chambering the round. The chamber will not accept anything over .338 overall neck diameter. Most NNY (PPU) brass works fine, some Winchester works, forget about S&B.
What I've started doing, is outside neck turning the brass to .010" thick. .316"+.010+.010 = .336", and no problems.

[gpidaho]

Yes, I've neck turned brass to get the larger bullets to fit the tight neck, Works just like bookworm said but in my case I'm not getting leading with the powder coated bullets and with the condition of my rifles bore, neck turning is more trouble than it's worth. Never going to be a target rifle anyway. Gp

[MT Chambers]

CBE of Aussie makes molds for oversize .303's, up to .316" at least.

[centershot]

I haven't done the pound cast yet, that's on the schedule for later this week, but I'm wondering about opening up the throat. Measurements of fired brass show a neck OD of .337". A .314" boolit will not start into that neck! I'll do the pound cast to verify but it looks like the throat is smaller than the bore. What if I ran an 8 mm throat reamer into it to open it up? What would be the down side of that? Split case necks? At that point I could size 8mm boolits to .319-.320" to fill the bore.

[bedbugbilly]

No experience with shooting M-N - used to own one many years ago but never shot it.

To answer your question though - sizing down from .325 to .318/.319 means downsizing the OD by .006 at a minimum. I think you'd have some issues with that - not only with reducing lube groove depth but just squeezing it down that far. I had a boolit mold that I bought for my 8mm Mauser that was oversize - it dropped them at around .327 - not what i wa told it would drop 'em at. I don't shoot anything but cat sneeze out of the Mauser but I have had the best luck with .323 with cast as the bore is .323 and that's about all I can get in the chamber of the rifle. Sizing down .004 to .323 was a PITA - it not only reduced the lube grooves but then resulted with flash around the base that had to be hand trimmed off - I had to use two separate sizing dies and reduce it .002 each push. It was a learning experience so worthwhile, but had I done a chamber cast first, I would have known that the mold wouldn't work. The mold was sold and I have stuck with the .323 even though I rule have liked to be able to use a .324 - .325. The rifle shoots fine though as long as I don't push them fast and works for what I shoot. I would imagine your M-N may be the same way. I don't PC but if you do, I'd sure try it in your M-N to see if that will let you push them a bit faster.

As everyone notes - your throat is going to determine what you use in the old girl - and you might have to have a mold cut special for it unless your lucky to and find one that will drop 'em where you need 'em for both the throat and bore.

I'm just curious - the M-N rifles seem to have various bore/throat sizes from what I read from time to time. Using your rifle as an example - if your bore is .317 but say your throat casts out for a .314 and that's all it will accommodate - is it possible to get the throat reamed to accept the diameter of boolit needed for your bore or is it too expensive of proposition? I don't shoot a lot of rifle so am not really aware of just what can be done in a case such as your's.

Best of luck to you!

Jim

[krallstar]

I haven't done the pound cast yet, that's on the schedule for later this week, but I'm wondering about opening up the throat. Measurements of fired brass show a neck OD of .337". A .314" boolit will not start into that neck! I'll do the pound cast to verify but it looks like the throat is smaller than the bore. What if I ran an 8 mm throat reamer into it to open it up? What would be the down side of that? Split case necks? At that point I could size 8mm boolits to .319-.320" to fill the bore.
What is the I.D for the inside of the fired case neck.

[centershot]

bedbugbilly - I've thought of that, I don't think a .317" reamer is a standard size, but I've not looked into it.

Krallstar - fired case neck ID is .313" :(

[centershot]

bedbugbilly - I've thought of that, I don't think a .317" reamer is a standard size, but I've not looked into it.

Krallstar - fired case neck ID is .313" :(

And just how do they get the throat SMALLER than the barrel groove ID??? It's all a part of the same piece of steel, right? What gives with this? I'm obviously not the only one with this problem!

[BHuij]

I'm in a similar boat - my 91/30 isn't as shot out as yours, but my Lee .312 185gr drops at .312" which is too small. I hadn't considered an 8mm mold, but I do plan on expanding the mold cavities in my Lee .312 so they drop more like .315" or .316". I've done it before on a Lee 6-cavity 9mm mold with excellent results. It took a few hours but has paid off. And since my .312 mold is only a 2-cavity I don't think it will be too difficult. I used the WEET method detailed in a sticky thread on this forum.

[centershot]

BHuij - Yes, I have considered doing that, it's a simple enough process on an aluminum mold.

[Petrol & Powder]

Seems like a lot of work for a Mosin-Nagant.

[waksupi]

I have an old M-44 Moisin-Nagant carbine with an oversize bore, it measures .317" OD. I have a Lee 312-185 mold that drops boolits at .314", too small to fill the bore but they shoot well at sub-sonic velocity and make good plinkers/gallery loads. For any type of heavier load I'm relatively sure this boolit would fail miserably so I've been eyeballing the 8mm selections. My question is this - Is sizing down from a nominal .325" to .318-319" going to materially deform the boolit, and can this be done in one pass or do I need 2 separate sizer dies? My alloy is 94-3-3, so around BHN 12, I have a Lyman 450 and a Lee Classic Cast loading press. I'm thinking Lee sizers in the Classic cast would do the job, just concerned about boogering up the boolit.

If you size them down, fill the lube grooves full first. The hydraulics will prevent the grooves from collapsing.

[centershot]

If you size them down, fill the lube grooves full first. The hydraulics will prevent the grooves from collapsing.

Excellent idea waksupi!

[Steve Steven]

Centershot,
your comment "I've thought of that, I don't think a .317" reamer is a standard size, but I've not looked into it." MSC the major machine shop supplier, has machine reamers in half thousands sizes
https://www.mscdirect.com/browse/tn/?searchAheadTerm=reamers&searchAhead=true&hdrsrh=true&typahddsp=Chucking+Reamers&navid=12106128#navid=12106128+4288018027+428813957 4

Steve

[waksupi]

Excellent idea waksupi!

Not my idea, Buckshot figured that one out years ago.