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Military Firearm Restoration Corner

Heavy Barrel Mosin


dirtyjim

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i picked up a barrel from a czech UK59 machine gun on gunbroker that had been threaded for a mosin. i put it on a modified hungarian m44 receiver i had sitting around. it headspaced just right & the extractor cut lined up perfectly. this thing is heavy, its .950 at the muzzel & 1.210 right before the boss where i think the carry handle for the machine gun was. its 1.170 behind the boss so i think i'll have it turned in a straight taper from that to the muzzel later or i might try drilling & tapping the boss to use like a barrel block to bed the rifle & free float the action & the rest of the barrel.the barrel is 24" long.

i need to pick me up a stock to test it out on now.

heavybarrelmosin2.jpg

 

heavybarrelmosin1.jpg

 

i'm sending these two barrels to be threaded for a mosin at the end of the week. one is a finned barrel in 7mm from a madsen light machine gun & the other is from a russian maxim. they are going on hex receivers & should make a couple intersting mosins when finished.

mosinsporterbarrels.jpg

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frank, i got the finned barrel from gunbroker a while back but sarco has them for about $30. they are new, if you cant find it on their website look in some of their shotgun news adds from about 6 months ago to get the part number. i also have a mauser project rifle with the same barrel on it.

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$30 bucks? dang, that's a good price for a new barrel, especially one so unique! what length are they, if you don't mind me asking? and they have enough meat to put on a large ring mauser?

 

heath

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heath,

they come out to right at 20" after cutting & threading the shank. there is plenty of meat to rethread to lr mauser. here is a pic of the one that i have on a mauser. i still need to ream the chamber on it.

cletus.jpg

the barrel at the shank is 1.175 dia. & is about 2 3/4" long before the finned area. the muzzel is .940 dia & the finns start out at 1.060 & end up at .825 at the muzzel.

i'm going to build a similar stock for the mosin.

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heath,

they come out to right at 20" after cutting & threading the shank. there is plenty of meat to rethread to lr mauser. here is a pic of the one that i have on a mauser. i still need to ream the chamber on it.

cletus.jpg

the barrel at the shank is 1.175 dia. & is about 2 3/4" long before the finned area. the muzzel is .940 dia & the finns start out at 1.060 & end up at .825 at the muzzel.

i'm going to build a similar stock for the mosin.

 

Jim, thanks for the info. Guess sarco will be getting some phone calls soon, Frank

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DirtyJim:

 

Who did the bolt handle on that M-N for you? Can you show a detail of the receiver and bolt?

 

i did the bolt handle. its not very hard but on the next one i'm going to move the bolt handle a little farther back.

on this one i have a space of .560 between the bolt handle root & the lug the original bolt handle was on. that is just about as far back as you can go & still keep the original safety functional. on the next one i build im going to space it back enough for a two piece scope mount & use a timney side safety trigger if they ever get them to the market. i have a set of sako mounts & rings that i may try to use on one of them.

 

i didn't take any pics while i was building it but on the next one i'll show step by step what all is involved.

basically what i did was i clamped two pieces of flatbar to the sides of the lug the bolt handle is on because the new bolt handle will have to be in the same position to slide through the back part of the receiver. i then drilled hole between the two pieces of flatbar as far back as i could without going into the cam area. the hole locates the root for the new bolt handle. i then forged a 3/8" grade 8 bolt into the shape i wanted & welded it to the bolt body & cut out the area in the side of the receiver to clear it. i used a piece of 1/8 wall pipe to make the rear bridge, 1 small piece if 1/8"x 1" flatbar could also be shaped for a rear bridge & welded on.

the rear bridge ends up being about 1/8" higher than the receiver ring.

 

its still rough in this picture & i'm not happy with the bolt handle so i'm going to cut it off and build a new one.

on the new bolt handle i'm going to use a section of 1/2" keystock for a root similar to the way a mauser bolt handle starts out. the bolt handle is also slightly swept back & will need to be straight up & down to keep it out of your trigger finger if you move it back any farther.

sportermosin1.jpg

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Very nice use of those great old barrels!

 

Several years ago I got an 8 mm machine gun barrel from Sarco for something like $20. It was originally chambered in the Swedish 8 x 63. Sarco made it sound like it was an 8-06 (of course it wasn't close). This is what made me put an extended bed on my minilathe. I couldn't begin to chuck it through the headstock. With the extension I turned down and threaded a large ring shank and chambered it by hand (with a home-made reamer) to 8-06. It turned-out butt ugly (it was among my first few tries) but was actually accurate with 185 gr corelocks and sized-up Lake City -06 brass. I can't quite remember how I made that brass. I must have necked up with 8 x 57 dies.

 

Ah, memories...

 

With a real lathe those machinegun barrels are bargain. The steel alone is worth more than the price. You get the rifled bore for free!

 

Aren't we lucky to still have these cheap parts floating around :))!

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  • 1 month later...

i haven't done anything else with it yet. between working out of town 4 days a week, working on my truck & trying to get a few of my other projects finished i've kinda neglected this one.

 

i have a couple more mosin projects on the drawing boards too.

i'm converting couple mosin boltheads for .473 dia. rimless cartridges for 22-250 & 220 swift projects.

i have a brand new tikka bull barrel for the 22-250 project & a 222 barrel from a remington 721 that i'm going to rethread for the mosin then rechamber it to 220 swift.

 

this is the first one i did.

i machined a bushing for the bolt face to reduce it down for a rimless cartridge & soldered it in place.

then i shimmed the extractor back .010" to make up for the difference in rim thickness, then filed the back of the extractor flush with the back of the bolt head. i also had to slightly deepen the extractor slot. i tested it out by putting it on my bannerman 30-06 conversion & cycling a few rounds.

it worked just fine.

 

bolt head before soldering the bushing in. the other bolthead is from my bannerman conversion, i used it for reference.

mosinboltfacebushing.jpg

 

finshed bolthead beside a standard mosin bolthead for comparison. it will hold the case against the bolthead in any position.

mosinrimlessbolthead.jpg

 

i think i'm going to redesign the bushing. if i extended the bushing slightly past the extractor i could eliminate the extractor cut on the barrel. i would have to shorten the barrel shank by the same amount that i extend the bushing.

if i made the o.d. of the bushing the same size as the o.d. of the bolt but put a step on it so it would slide into the bolt face then tig weld it to the bolt. i don't think it would transfer enough heat from the rim to the bolt head to cause any problems since all of the welding would be done on the lip of the bolt face.

i could also make a bushing to fit 7.62x39 & .223 size caseheads. i was thinking about trying to adapt an ejector similar to whats used in a 88 commision rifle for the 7.72x39 & .223 size case heads.

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Why do you have to extend the bushing to eliminate the extractor cut on the barrel?

 

There are two reasons that I can think of for the extractor cut in the barrel on MNs:

 

1. More case head support

 

2. To leave enough metal to provide a headspace surface for the rimmed case

 

I lean more towards #2 more than #1, or a combo of the two with #2 being more prevalent. Looking at the MN barrel shank, a tiny little lip is left where the extractor rotates, for an arc of about 110 degrees. Even without that lip (If it were to be milled out without it), there is still plenty of case head support.

 

Your photo with the case in the bolt is telling; as-is, the only part of the case that would stick out of the chamber would be the extractor groove. The strongest part of the case and everything forward would be fully supported.

 

Another interesting point is that the stock extractor is designed to slide over the large diameter rim of the Russian case. With the large rim gone on your conversion, does the tip of the extractor need to stick out as much? You could take some meat off the face without affecting either function or strength.

 

I don't know that the funnel-breeched M70 provides as much. I don't have an M70 Classic to compare it to though.

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i don't think it would be absolutely necessary to extend the bushing to do away with the extractor cut but i do think extending the bushing might make the conversion work just a little bit better. from the extractor groove forward would be inside the chamber so casehead support shouldn't be an issue.

the bushing would be extended by about .055

you cant really shorten the tip of the extractor enough to make a difference, probably .010 at the most

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both the UK59 machine gun barrel & the maxin barrel will remain in 7.62x54r so there will be no feeding problems there.

the others i will have to do some mods to the magazine & ejector assembly for them to work as anything other than a single shot. i'm going to copy the way my bannermans ejector & interuptor way modified for the other calibers. i'll post pics of them when i get started on it.

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