Converting a modern rifle to 7.5 swiss

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Hannibalbarca
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Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

Hello, does anyone here know a good candidate to convert a rifle to 7.5 swiss?
Id like for it to have a detachable magazine with high capacity magazines available for purchase.
i imagine it would have to be a 30-06 rifle simply due to cartridge length.
also should the barrel be chambered for 30-06 or 308 winchester?
would the extra chamber length be a safety and or accuracy concern?
if so then it would have to be a 308 barrel rechambered for 7.5 swiss, correct?
the bolt face would also need to be resized from .473 to .498 inches.

i know what everyone will say, get a k31, well theyre fairly expensive now and hard to find. besides modern production rifle that can be had for 300 to 500 do 1 inch groups regular, fairly accurate.
now id like the barrel to be long, at least 26 inches, to get the best velocity from 7.5 swiss.
i really like 7.5 swiss and gp11 is very cheap while match grade 308 is very expensive.
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Re: Converting a modern rifle to 7.5 swiss

Post by jreinke »

Buy a used Savage 110 in snot-6, preferably one with the newer center feed magazine. That will eliminate any possibility of feeding problems.
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Re: Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

jreinke wrote:Buy a used Savage 110 in snot-6, preferably one with the newer center feed magazine. That will eliminate any possibility of feeding problems.
How would the rechambering work since 30-06 is longer? Wouldn't that also be inaccurate?
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Re: Converting a modern rifle to 7.5 swiss

Post by jreinke »

You need to convert a 30-06 because the magazine length is similar, the 308 win is too short. Basically what you'd do is get a barrel nut wrench and remove the barrel. Then insert a 30-06 go gauge in the chamber and measure how much is sticking out. Then you'll chuck the barrel up in a lathe. After comparing the chamber specs on both the SAAMI and CIP drawings, looks like you'll have to trim 0.300" off the chamber end of the barrel. This is so when you cut your new 7.5x55 chamber, you'll get a clean throat and not have remnants of the 30-06 throat. You'll also have to extend the barrel threads by 0.300" too. Then cut the new chamber, ensuring that you have exactly the same measurement when you insert a 7.5x55 go gauge in the chamber as with the 30-06 gauge in the 30-06 chamber. Finally, you'll need to disassemble the bolt completely. Put the bolt head in the lathe and then widen the cup on the bolt face with a 1/2" carbide end mill. Make sure that the end mill DOES NOT touch the bolt face! Then just reassemble the rifle. FYI, the actual measurement to be removed from the barrel was something like 0.286", but Savage barrel threads are 20 tpi, which equates to 0.050" of lateral movement for one turn of barrel, so 0.300" equals 6 threads. That way if you rifle you buy has open sights, they should be still aligned when everything is all said and done.
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Re: Converting a modern rifle to 7.5 swiss

Post by jlwilliams »

The cost of converting the rifle so that you can shoot cheap surplus ammo could buy a good stash of .308 ammo. If you spend the time and money on the rifle, would you want to shoot cheap surplus ammo through it? I picked up a bolt action in 7.62x39 a while back hoping to take advantage of all the cheap ammo. No joy there. I only shoot good, brass cased commercial ammo through it because milsurp and Wolf suck.

If the goal is cheap, accurate shooting, reloading is the most cost effective path. Second most cost effective is buying case quantity online.

I don't know where you are, but if you are in the US there are lots of good deals on gun store shelves on used hunting rifles in .243, .308, .270, 30-06 and so on. You can score a good accurate shooter for way less than full retail and you can either buy bulk ammo (any caliber, delivered to your door) or buy a press and roll your own. I see where you are going, and it's a neat idea, but the juice may not be worth the squeeze to convert a new rifle to an obsolete cartridge.
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Re: Converting a modern rifle to 7.5 swiss

Post by doubloon »

jlwilliams wrote:...
If the goal is cheap, accurate shooting, reloading is the most cost effective path. Second most cost effective is buying case quantity online.
...
This.

There appears to be only one bulk choice in 7.5 Swiss under $0.75/rnd, (Berden primed, so craptastic for reloading) after that there is only one bulk choice in 7.5 Swiss for ~$0.75/rnd (Boxer primed) which is about the same price as multiple choices in 308 Win. and both are basically the same bullet.

If an uber 7.5 Swiss build doesn't shoot the one available bullet well then you have to reload anyway.

The only goal that makes sense down this path is to have something nobody else has.
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Re: Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

doubloon wrote:
jlwilliams wrote:...
If the goal is cheap, accurate shooting, reloading is the most cost effective path. Second most cost effective is buying case quantity online.
...
This.

There appears to be only one bulk choice in 7.5 Swiss under $0.75/rnd, (Berden primed, so craptastic for reloading) after that there is only one bulk choice in 7.5 Swiss for ~$0.75/rnd (Boxer primed) which is about the same price as multiple choices in 308 Win. and both are basically the same bullet.

If an uber 7.5 Swiss build doesn't shoot the one available bullet well then you have to reload anyway.

The only goal that makes sense down this path is to have something nobody else has.
I have around 1920 rounds of 7.5 Swiss that I bough for around 39 cents a while back when I had my k31. The bore wasn't very good so I sold it.
Been setting on it since then.
It was supposed to be my precision shooting long distance and rifle and the surplus ammo is pretty much all match grade and ammo still isn't too expensive.

Reloading also isn't that much of a problem since you can convert the brass to boxer prime and you can get a lot of reloads from the brass(I think like 15 or more since it's a fairly low pressure cartridge when compared to 308 Winchester).
So when I get into reloading it will be just as cheap as 308 but will take longer at first since it needs to be converted to boxer prime.
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Re: Converting a modern rifle to 7.5 swiss

Post by jlwilliams »

It's your money to do as you will with. Just be aware that the conversion will cost at least as much and likely more than a good K31. They aren't as cheap as they used to be, but neither is a custom rifle. You can build your custom rifle in any caliber you want, that being the very definition of "custom" and if you want to feed your new rifle 40 year old military surplus ammo ain't no one can stop you. I've done sillier things.

If I were in the market for a good, accurate bolt action rifle and I had close to 2k of that ammo stashed I'd sell the ammo and buy a new rifle. You could get at least $.50 a round, probably a bit more and get that quickly. That's a new rifle and a few bucks toward the optics or a modest factory combo deal and a few hundred rounds of ammo. Alternatively, if I had that ammo and regretted selling the old war horse, I'd replace that with a better example of the breed.

Building a new rifle in 7.5 Swiss sounds neat. I don't think it "makes sense" but that's why I'm not doing it. You are. Happy smithing and don't forget to post pics.
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Re: Converting a modern rifle to 7.5 swiss

Post by doubloon »

Hannibalbarca wrote:...
I have around 1920 rounds of 7.5 Swiss that I bough for around 39 cents a while back when I had my k31. The bore wasn't very good so I sold it.
Been setting on it since then. ...
So an investment of roughly $750 worth of old ammo which might could be sold for ~$875-$1000 (Berden) is driving the decision?
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Re: Converting a modern rifle to 7.5 swiss

Post by jlwilliams »

doubloon wrote:
Hannibalbarca wrote:...
I have around 1920 rounds of 7.5 Swiss that I bough for around 39 cents a while back when I had my k31. The bore wasn't very good so I sold it.
Been setting on it since then. ...
So an investment of roughly $750 worth of old ammo which might could be sold for ~$875-$1000 (Berden) is driving the decision?

Google tells me that Bass Pro has Savage Axis rifle scope combo deals in 4 different cartridges (.243, 7-08, 308, 270 or .308)for $349 each. Not a high end rifle, but a good shooter. Selling the old ammo would buy a complete set up complete with new m manufactured ammo and a set of dies.

I don't mean to be disparaging of what you want to do, but I do want to point out the economics. Myself, I've blown stupid money on projects that I wish I had looked at the economics of differently than I had before I jumped in. Case in point, I've spent money converting old guns to fire "cheaper" rounds. In the process I blew more money than I would have by buying two life's supplies of ammo without messing with the gun. I built a sweet supporter out of a Mosin Nagant that when it was done was at best a 4" @ 100 yard gun. I could have (should have) bought a Savage 110 brand new for the money I spent on that one, and the Savage would have been a way better shooting gun.

If you want to build a custom gun, build a custom gun. If you want to feed it corrosive ammo that's likely older than you, cool enough. Just be aware that you could either buy an antique rifle for the ammo or sell the ammo and have a new gun, your choice, for less money.

Question is, do you want a rifle to shoot or do you want a project? Once you define what YOU want to do, do THAT no matter what some geezer on a forum who's bent about the stupid money he blew has to say about it.
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Re: Converting a modern rifle to 7.5 swiss

Post by doubloon »

jlwilliams wrote:...
Question is, do you want a rifle to shoot or do you want a project? Once you define what YOU want to do, do THAT no matter what some geezer on a forum who's bent about the stupid money he blew has to say about it.
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Re: Converting a modern rifle to 7.5 swiss

Post by mbogo »

Put the bottle down and step away from the keyboard.. :lol:

In order to bring this conversion to fruition, you'd have to buy a rifle with a suitable length action. This will cost you in excess of $300.

You'd have to re-barrel it (the 7.5x55 uses a different diameter bullet than an '06; if you're looking for "match" accuracy, you shouldn't use undersized bullets). This will cost you in excess of $300.

You'd have to open the bolt-face.

You'd have to work on the feed rails.

You'd have to work the magazine lips and followers.

Sell the ammunition and use the proceeds to buy a Savage in .308 Remington (or .260 Remington or 6.5 Creedmoor if you prefer). Then, handload for it. You'll be out shooting it long before your other idea comes together.

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Re: Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

mbogo wrote:Put the bottle down and step away from the keyboard.. :lol:

In order to bring this conversion to fruition, you'd have to buy a rifle with a suitable length action. This will cost you in excess of $300.

You'd have to re-barrel it (the 7.5x55 uses a different diameter bullet than an '06; if you're looking for "match" accuracy, you shouldn't use undersized bullets). This will cost you in excess of $300.

You'd have to open the bolt-face.

You'd have to work on the feed rails.

You'd have to work the magazine lips and followers.

Sell the ammunition and use the proceeds to buy a Savage in .308 Remington (or .260 Remington or 6.5 Creedmoor if you prefer). Then, handload for it. You'll be out shooting it long before your other idea comes together.

mbogo
Isn't that just the bore size?
7.5 Swiss and 308 Winchester and 30-06 should be the same groove size.
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Re: Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

jlwilliams wrote:
doubloon wrote:
Hannibalbarca wrote:...
I have around 1920 rounds of 7.5 Swiss that I bough for around 39 cents a while back when I had my k31. The bore wasn't very good so I sold it.
Been setting on it since then. ...
So an investment of roughly $750 worth of old ammo which might could be sold for ~$875-$1000 (Berden) is driving the decision?

Google tells me that Bass Pro has Savage Axis rifle scope combo deals in 4 different cartridges (.243, 7-08, 308, 270 or .308)for $349 each. Not a high end rifle, but a good shooter. Selling the old ammo would buy a complete set up complete with new m manufactured ammo and a set of dies.

I don't mean to be disparaging of what you want to do, but I do want to point out the economics. Myself, I've blown stupid money on projects that I wish I had looked at the economics of differently than I had before I jumped in. Case in point, I've spent money converting old guns to fire "cheaper" rounds. In the process I blew more money than I would have by buying two life's supplies of ammo without messing with the gun. I built a sweet supporter out of a Mosin Nagant that when it was done was at best a 4" @ 100 yard gun. I could have (should have) bought a Savage 110 brand new for the money I spent on that one, and the Savage would have been a way better shooting gun.

If you want to build a custom gun, build a custom gun. If you want to feed it corrosive ammo that's likely older than you, cool enough. Just be aware that you could either buy an antique rifle for the ammo or sell the ammo and have a new gun, your choice, for less money.

Question is, do you want a rifle to shoot or do you want a project? Once you define what YOU want to do, do THAT no matter what some geezer on a forum who's bent about the stupid money he blew has to say about it.
Well match grade 308 or 30-06 or really thing else is very expensive. Like 1.40 or 1.50 dollars per bullet. 7.5 Swiss is only 52 cents right now and I have just over 1900 rounds.
I want a precision shooting rifle and I want to have lots of cheap ammo - 7.5 Swiss also isn't corrosive.
I can still reload it and use the same bullets. I probably have 30,000 reloaded rounds in that brass, if I choose to reload and I will but now.

So with this cost of the ammo spending 350 or maybe less on a quality but budget rifle and then timing the bolt head and reaming the chamber for a couple hundred more is less expensive than just buying it and then buying match 308 ammo.
The projectiles for match 308 are almost as expensive as a 7.5 Swiss roun.

I would buy a k31 they're just not available.
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Re: Converting a modern rifle to 7.5 swiss

Post by mbogo »

It's your time and your money. Waste it as you will.

There are K31s for sale on the auction sites.

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Re: Converting a modern rifle to 7.5 swiss

Post by doubloon »

Hannibalbarca wrote:...
I would buy a k31 they're just not available.
https://www.gunsite.com/k31_for_$300
Hannibalbarca wrote:...
Well match grade 308 or 30-06 or really thing else is very expensive. Like 1.40 or 1.50 dollars per bullet. 7.5 Swiss is only 52 cents right now and I have just over 1900 rounds. ...
bulk "match" Boxer primed ammo in 308 is the same price (maybe a few cents cheaper) as bulk PPU Boxer primed ammo in 7.5, if you want to step down to surplus Berden primed then there's 308 to be had for the same price with a Berden primer

At least the 308 stuff actually has "match" in the name.

Not trying to talk you out of it, just looking at the facts.

Like JW says it's your money spend it how you want, there are plenty of K31s for sale out there.
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Re: Converting a modern rifle to 7.5 swiss

Post by Hannibalbarca »

doubloon wrote:
Hannibalbarca wrote:...
I would buy a k31 they're just not available.
https://www.gunsite.com/k31_for_$300
Hannibalbarca wrote:...
Well match grade 308 or 30-06 or really thing else is very expensive. Like 1.40 or 1.50 dollars per bullet. 7.5 Swiss is only 52 cents right now and I have just over 1900 rounds. ...
bulk "match" Boxer primed ammo in 308 is the same price (maybe a few cents cheaper) as bulk PPU Boxer primed ammo in 7.5, if you want to step down to surplus Berden primed then there's 308 to be had for the same price with a Berden primer

At least the 308 stuff actually has "match" in the name.

Not trying to talk you out of it, just looking at the facts.

Like JW says it's your money spend it how you want, there are plenty of K31s for sale out there.
If you look at the quality of those k31s they're not that great and they're at least 500 bucks.
I found a really nice one on armslist(I mean collector grade for only 600) but it sold, unfortunately(less than 3 days up).

75 cent match grade 308? Where?
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Re: Converting a modern rifle to 7.5 swiss

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Hannibalbarca wrote:...
If you look at the quality of those k31s they're not that great and they're at least 500 bucks.
I found a really nice one on armslist(I mean collector grade for only 600) but it sold, unfortunately(less than 3 days up). ...
sounds like a valid argument for selling the ammo and getting a modern rifle
Hannibalbarca wrote:...
75 cent match grade 308? Where?
everywhere and it's every bit as much match grade ammo as that surplus 7.5

Look, you're not going to convince me to agree with you that sticking with the 7.5 is the right decision so ignore me and spend your money how you want.
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Re: Converting a modern rifle to 7.5 swiss

Post by jlwilliams »

Cheap surplus 7.5 isn't "match grade" even if it is Swiss. The goals of a cheap precision rifle and cheap ammo are contradictory and self defeating. The closest you can get to that would be 5.56 or 7.62x51 if you stick to the better countries of origin. 5.56 beats all for cheap and accurate in the same round. If your available rifle range is 400 yards or less then 5.56/.223 is the best cheapest option. If you really want bigger holes in your targets, then go 308.

Seriously, the tales on the web about old bolt action service rifles and military ball ammo being capable of eyeball shots at great distance are hugely exaggerated. I've heard stories about the Enfield or the K31 or the Springfield and Mauser sniper rifles of that era. None of them hold up when tested. A K31 or an 03-a4 or any WWII era sniper rifle with service ammo is not as accurate as a brand spanking new rifle with top shelf (not cheap) ammo. Surplus rifle plus cheap ammo doesn't equal precision rifle, even if it's "made in Switzerland."

You need the right projectile for your barrel. Right bore or right groove isn't enough. Yes, if you re chamber a .308 barrel you can fire 7.5 through it safely, but not with "match grade" accuracy. Buying a 30-06 rifle, swapping and reaming a barrel, fitting magazines and so on will yield you a functioning but inaccurate rifle for more cost than either buying the K31 ($600 is way less than this adventure will end up costing) or just buying the 30-06 and NOT rebarreling it.

In the first post you mention $300 to $500 dollar rifles shooting accurately out of the box. That's true. Converting one of those to 7.5 won't be a cheap job. You need a long action plus a new barrel before you can buy or rent a reamer and a set of gauges. You could use a .308 barrel but if you want accuracy you need a purpose built 7.5 Swiss short chambered barrel. You would need to do some lathe work. Maybe you have that lathe, maybe your paying to get it done. It's all doable, but not free. You will be into this for a grand before you put a scope on it much less pull the trigger. If it's worth at least a thousand dollars to you to have a 7.5 Swiss precision rifle, rock on. Or buy a Ruger American or a Savage or Howa and be done with it.

I'm done. I've posted all that I can possibly post on this topic. Do what you want with your money. I hope you spend it wisely, but it's up to you. Have fun. Post pictures. Just don't whine about the cost when you are done or (more likely) abandon the project when you run out of money.
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Re: Converting a modern rifle to 7.5 swiss

Post by fishman »

I agree with these guys, selling the ammo makes the most sense by far. But if you do go 7.5, the easiest option might be having a custom TC encore barrel made in 7.5. There's a few mods that can easily be made to that gun that can make it very accurate. My .270 win encore shoots .75MOA with my reloads using coyote hunting bullets. This would not be cheap, but it would be easy. I'm not sure what an encore lower costs, but custom barrels can be had for under $500.
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Re: Converting a modern rifle to 7.5 swiss

Post by Capt. Link. »

Buying a K-31 would be the best option but if you insist I could cut you a barrel if a viable blank can be had.I wish that I bought one years ago when the prices were better.The good news is prices are dropping so keep your eyes open.
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