Rebarrelling and rechambering a damaged svt 40

H Wally

H Wally

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I'm looking for input on an appropriate caliber to rechamber a 7.62x54R SVT 40. The gun in question has an unfixable chamber that is pretty much a write off so I can put any bore diameter barrel on it and ream for any caliber. End goal would be either an SVT look alike in a different caliber OR an SVD clone.

- My preference is for a caliber that is commonly commercially available or easily reloadable. The less commercially available the better performing the caliber would have to be to make up for it.

- My initial choices are:
1) 308/7.62x51N; It's common commercially, lots of components, good multi purpose round.
Pros - commercially available, surplus available and I already reload for it.
Cons - Higher Max pressure of 7.62 Nato/308 ( Approx 62 000 psi) than 7.62x54R ( Approx 57 000 psi )
Solution - safe operating pressures of action might be higher than the cartridge max pressure, therefore allowing safe operation. Proofing would be required, and frankly I'd probably always be a little leery of it.

2) 7mm-08; Less common than 308, but better ballistics.
Pros - ballistically superior to 308 with little sacrifice in bullet weight.
Cons - 7mm-08 has listed max pressure of approximately 61 000psi; I don't reload for it and don't really want another caliber to reload.

3) 260 Remington; Less common still - better ballistics than both.
Pros - a good cartridge with good ballistic coefficient - better than 7mm and 308, however less commercially available.
Cons - Still above 7.62x54R pressures, but only 60 000psi now; I don't reload for it and don't really want another caliber to reload.

4) 6.5x55 - far less common, but suited to the long action, has good ballistics and I already reload for it.
Pros - Good variety of components, good ballistics, I already shoot it; 55 000psi max pressure puts it within mosin territory
Cons - not as commercially available

5) 7.62x54r - for simplicity, just make a new barrel... It'd be better to sell the gun for parts in this case though as it's not worth my time and isn't particularly interesting.



This project is intended to teach me about rebarreling and rechambering, so it's not meant to be cost effective or logical, but rather to be a learning experience.
Please keep this on topic of calibers to be rechambered to - I recognize that it's a milsurp and as such its value will be lost, that it has historical significance, that I will not make my money back on it and that it will require more work than swapping barrels, however in the name of not derailing the thread lets please keep it to this topic.
 
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Just get a Rem 700 take off barrel in .308 bore and re-chamber to 7.62x53R. MN barrels are 1"" 1-16 TPI or rebore to 9.3x54R..........Harold
 
If the mag will accept it have you though of doing it up in 45-70? I have always liked the idea of a semi auto 45-70. The action is certainly strong enough to handle even the hot loads.
 
bearhunter said:
If the mag will accept it have you though of doing it up in 45-70? I have always liked the idea of a semi auto 45-70. The action is certainly strong enough to handle even the hot loads.
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You're really big on the 45-70 aren't you? I must admit, having an auto-loading 45-70 would be incredibly badass, if not disturbingly perturbing.

As far as conversion, the barrel is trivial. The hard part of an autoloader is making it work. Bolt, magazine and gas system all have to be modified or outright replaced, none of which are easy due to a complete lack of precedent for such modifications. The difficulty of working with 8x57 descendants is that bolt modification becomes an absolute necessity (due to head diameter), and reliability is rapidly called into question. If you can figure out how to get the bolt to work, the rest is simple trial and error and some basic, if extensive, fabrication. My personal, and purely theoretical choice would be the 7mm-08, simply because it seems to be a wonderful cartridge. However, this opinion is based solely on theory and not on any personal experience with said cartridge.
 
I vote 6.5x55. You already reload for it so no need for new components, you can trust the current action with the pressure being lower. The cartridge is of the same era, it would like having the lovechild of the Mosin and a Swedish Mauser! I wonder if trade ex has barrels available?
 
I would go with rimmed rounds myself to try and not mess with the bolt head as much. Calibers that would be cool to try for it if you want a 'historical' caliber theme would be .303 or maybe if you wanted to get really tricky 8x56r
 
Lol - thanks for the thoughts guys. I'd ask we try to stick to caliber choice as how to do the modifications is a totally different and much larger kettle of fish.

I'm personally leaning towards 6.5x55, but that's partially because I don't know enough about the SVT action being able to handle the extra 5000psi of pressure that 308 can generate within its limits. If someone could discuss that either for or against it I'd be interested to hear, as 308 is definitely the "logical" choice.
 
H Wally said:
Lol - thanks for the thoughts guys. I'd ask we try to stick to caliber choice as how to do the modifications is a totally different and much larger kettle of fish.

I'm personally leaning towards 6.5x55, but that's partially because I don't know enough about the SVT action being able to handle the extra 5000psi of pressure that 308 can generate within its limits. If someone could discuss that either for or against it I'd be interested to hear, as 308 is definitely the "logical" choice.
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The biggest argument against a rimless round is the fact that the bolt would require some serious modification to make it accept rimless rounds. Not saying it can't be done just saying it would be difficult.
 
Blastattack said:
You're really big on the 45-70 aren't you? I must admit, having an auto-loading 45-70 would be incredibly badass, if not disturbingly perturbing.

As far as conversion, the barrel is trivial. The hard part of an autoloader is making it work. Bolt, magazine and gas system all have to be modified or outright replaced, none of which are easy due to a complete lack of precedent for such modifications. The difficulty of working with 8x57 descendants is that bolt modification becomes an absolute necessity (due to head diameter), and reliability is rapidly called into question. If you can figure out how to get the bolt to work, the rest is simple trial and error and some basic, if extensive, fabrication. My personal, and purely theoretical choice would be the 7mm-08, simply because it seems to be a wonderful cartridge. However, this opinion is based solely on theory and not on any personal experience with said cartridge.
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Globe Firearms converted thousands of SVT38/40 rifles to 303Brit. They set the barrels back and refitted the gas tube as well as shortened the barrels. They functioned well, with good ammo and were accurate. Rumor has it they were Finn captures.

As far as being big on the 45-70. Not particularly but it would be unique to say the least. On top of that, it would be a hellishly effective hunting/bush protection rifle.
 
To make it easier id stick with a round that has a rim the same as the 54r saves some of the harder mods. 303 would be my best bet for it. May even feed out of the mag un modified. It is the gas system and the right sized holes that will be a problem. Start small and work up slowly.
 
.303 British doesn't work well. The case head is entirely different with the arc on the rim of the 7.62. Globco Mohawks are notorious for bad headspace. Only done because proper ammo wasn't available.
If you opt to go with a rimless cartridge, you have a nightmare ahead of you. Never mind the bore diameter being .311". You'll have to radically alter the bolt head, extractor etc to make the thing work with a rimless. Anyway, rebarreling and rechambering are totally different operations anyway. See if you can find a used barrel, plus an action wrench.
 
sunray said:
.303 British doesn't work well. The case head is entirely different with the arc on the rim of the 7.62. Globco Mohawks are notorious for bad headspace. Only done because proper ammo wasn't available.
If you opt to go with a rimless cartridge, you have a nightmare ahead of you. Never mind the bore diameter being .311". You'll have to radically alter the bolt head, extractor etc to make the thing work with a rimless. Anyway, rebarreling and rechambering are totally different operations anyway. See if you can find a used barrel, plus an action wrench.
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Sunray. Do you speak from experience here or just hearsay??? I've done similar things and lived to regret it. Had to apologize for that today.

I've owned and used several of the Globe SVT offerings. They were all well finished, accurate and headspace was just fine on all of them. When they set back the barrels, they also refaced the bolts and modified or changed out the extractors. At least the rifles I had were done that way.

There was a shop in Vancouver that was converting Svt 38-40 rifles that they were converting to 303 Brit. I know they did as little as necessary to get them to function. Also, a lot of people were shooting surplus ammo of questionable quality out of them. There was a large batch of RG that was being marketed by International Firearms that hang fired, sputtered, squibbed, you name it. It was all on chargers and packed in 50 round bandoliers, made of heavy canvas. This stuff was wartime to early fifties dated. Looked great. Just didn't function well.

This is one of the reasons the Globe rifles got a bad rep. They digested just about any commercial ammo without a hiccup.
 
Thanks for the info guys - I guess there isn't much aside from enfield barrels that's a close fit to the SVT's dimensions. Ah well, was worth finding out in case something fit easily.
 
mbogo3 said:
rebore to 9.3x54R..........Harold
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I vote for 9.3x53R rebore. Because, who else will have one? A semi-automatic big-bore rifle with a muzzle brake will create one badass bush gun. You can take down a moose and a charging bear all at the same time with lightning speed.
 
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