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Posted: 9/14/2021 10:00:41 PM EST
I usually post these in the Gunsmithing forum, but let’s see if It can survive in GD.

I made a friend at the range a few years back, chatted and swapped guns, had similar tastes in guns and shooting philosophy.

Ran into him at an FFL, I was picking up a Parker Hale receiver, he was picking up two barreled K-31 receivers. He’s a bit of a K-31 nut, already had several originals.

One thing led to another and I ended up borescoping his newly acquired toys.

“this one was in the infantry, and this one was in the home guard!”

So he decided to build the “good” barreled action into a sporter.

He found a Richards Sporter stock, I pillar bedded and glass bedded it for him, and did the final innletting.

He sanded and finished it.

Link to Bedding Thread https://www.ar15.com/forums/general/What-s-Arfcom-Favorite-Bedding-Compound-UPDATE-Bedded-Rifle-Photos-/5-2407903/

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It shot really good.

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But what to do with the other receiver with the crap barrel?
Link Posted: 9/14/2021 10:04:17 PM EST
[#1]
Any problems with ejecting cases hitting the scope ?
Link Posted: 9/14/2021 10:13:18 PM EST
[#2]
Love me some K-31. And I've got the strangest boner right now...   Nice rifle!
Link Posted: 9/14/2021 10:14:59 PM EST
[#3]
Since the factory guns shoot so well, we started wondering what one could do with a good barrel.

The idea of a K-31 based target rifle was born.

So off to google he went to find someone to build one for him.

He didn’t find anyone.

Seems like maybe one or two people in the US had ever done it.

We found photos of a gunsmith in New Hampshire holding one, but he never made contact with him.

There was one you tube video of a guy rebarreling one, but he bored out the old barrel stub and screwed in a cheap blank and chambered it to a more common US cartridge.

Not what my friend wanted to do.

All the internet said NAY! Can’t be done. too complicated, with the cammed  rotating straight pull bolt, the end of the barrel has a complicated ramp, extractor cuts, all has to be timed perfect, it’s 1.45 inches diameter, and metric threads.

Looks like this.

Attachment Attached File



Gotta have a 4 axis CNC machine and someone to write the code! The internet said...
Link Posted: 9/14/2021 10:27:36 PM EST
[#4]
What to do with the old barrel and receiver?

Make one cheaply as possible and use as a truck gun or trainer for new shooters.

Or just use the receiver and add a new barrel of a different caliber.

Or open the bore up to fire a .308 win cartridge. Or a .338 caliber.

338x55 Swiss sounds pretty cool….



Link Posted: 9/14/2021 10:29:30 PM EST
[#5]
So we went to see my buddy Russ, who owns an an R&D CNC shop. He makes neat stuff, prototype surgical tools, and things that go in space.

Sure said Russ, I can do it. For about a thousand bucks.

Did I mention my friend is cheap ?

He was discouraged, seemed like there was no way to get his dream rifle built.

It’s all bullshit anyway I told him. This CAN be done on standard machine shop equipment, manually.

The rifle was built in 1916.

Manual machines.

But it is the swiss watch of rifles, so it wasn’t going to be easy.

So we went to see my neighbor, a retired, self taught machinist, who loves a challenge to play with in his backyard machine shop.

Attachment Attached File


The first step was to figure out if he coul even cut the metric threads. After a lot of research, he finally figured out a way to re-gear his Southbend 9 inch and cut the correct thread pitch.

Attachment Attached File
Link Posted: 9/14/2021 10:34:00 PM EST
[#6]
Taaaaag arooski
Link Posted: 9/14/2021 10:36:21 PM EST
[#7]
Purchased four when I had the flow, but always wanted one in 7.62 NATO.  Can be done, but is very expensive.  I believe you can (or could back
In the day) send a rifle back to Switzerland and have the weapon rebarreled, (Hamerlli?) but it was very expensive even then.  

Issue GP11 is basically match grade ball, so I suppose there never was a big demand for the work to begin with.  

Fantastically accurate rifles.
Link Posted: 9/14/2021 10:36:27 PM EST
[#8]
My friend the K-31 nut was intrigued, so we pressed on. My neighbor spent his spare time for a few weeks tinkering with set ups, figuring out how to set up and make the cuts.

First he turned some dummy barrel stubs in aluminum to test the threads and see if he could reproduce the barrel thread pattern.

Attachment Attached File
Link Posted: 9/14/2021 10:44:04 PM EST
[#9]
Having proved that he could make the thread pattern, my neighbor started trying to figure out how to reproduce the ramp and extractor cuts. This is what he came up with.

Attachment Attached File


The ring is scribed with the witness mark, and cuts, start and finish of the ramp, like so.

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Then placed on the new part ( after it’s been tourqued onto the receiver and stamped with a witness mark)
Like so, and all the scribe marks transferred.

Attachment Attached File
Link Posted: 9/14/2021 10:46:58 PM EST
[#10]
I don’t have many gun regrets but, I regret not getting a couple of those when they were cheap and plentiful not that long ago.
Link Posted: 9/14/2021 10:49:54 PM EST
[#11]
Next the stub got set up in the mill, and the cuts made, and the ramp finished.

Attachment Attached File


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Link Posted: 9/14/2021 10:51:14 PM EST
[#12]
OST, OP you and me must be cut from the same cloth, I LOVE this kind of shit. Can’t wait to be retired!
Link Posted: 9/14/2021 10:51:42 PM EST
[#13]
Link Posted: 9/14/2021 10:55:08 PM EST
[#14]
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So the next thing was to check functionality.

The bolt went into battery and locked up on the new barrel stub.

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Attachment Attached File


Link Posted: 9/14/2021 11:00:31 PM EST
[#15]
At this point, we had my friend the K-31 nut was convinced that my neighbor, the backyard machinist, could get the barrel fitted on his action.

The K-31 Target rifle dream was alive, so he ordered a 1.5” diameter, 28” , profiled to 1.25 at the muzzle, Krieger Stainless steel .308 barrel.

We’re going all the way!

K-31 Target Rifle!

Stay tuned for updates!
Link Posted: 9/14/2021 11:07:59 PM EST
[#16]
Good thread OP-thanks for sharing :)
Link Posted: 9/14/2021 11:36:34 PM EST
[#17]
Tagged for more!  
Link Posted: 9/14/2021 11:45:56 PM EST
[#18]
NICE!

Definitely tagged.

Good show so far.
Link Posted: 9/14/2021 11:47:47 PM EST
[#19]
Awesome thread!
Link Posted: 9/14/2021 11:50:16 PM EST
[#20]
I love this thread.  What I had read was that rebarreling was something too complex to consider.

I have a K31 made in 1947.  I had it scoped with an 4 power Unertl, but I found a 10 power leupold on GB, so that's what's going on it.
Link Posted: 9/15/2021 12:15:51 AM EST
[#21]
The K/G11 actions are much easier to rebarrel, the cam action and lugs are in the back of the receiver.

Never once have I seen a bad Swiss bore, except on Vetterli's. Curious how it was determined infantry versus home guard? Especially from just a barreled action.

Out of the couple dozen K31's I have, only one scoped and I used the Graf's clamp on mount, left it all stock otherwise. I have 3 'u-fix-ems' that I got from AIM for $59. Mostly broken lumber and/or mismatched IIRC.

I'm a machinist, might try something similar with one of my junkers. And kudos for using a horizontal mill, not often seen these days.
Link Posted: 9/15/2021 12:20:39 AM EST
[#22]
Oh this is good.
Link Posted: 9/15/2021 12:23:42 AM EST
[#23]
<---Wants to know more
Link Posted: 9/15/2021 12:30:08 AM EST
[#24]
I got my K-31 for all of $85, back when they first came stateside.  I got a St. Maries clamp on scope mount on sale, and mounted a cheap Bushnell scope to the rifle.  I managed a 0.43" group of five at 100 yds or so, and that was with Prvi ammo, not GP-11.

Iraqvet8888 on YT got a target rifle made from a K-31:





Other K-31 vids he did:

https://www.youtube.com/results?search_query=iraqveteran8888+k31
Link Posted: 9/15/2021 5:07:45 AM EST
[#25]
Link Posted: 9/15/2021 5:12:51 AM EST
[#26]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
The K/G11 actions are much easier to rebarrel, the cam action and lugs are in the back of the receiver.

Never once have I seen a bad Swiss bore, except on Vetterli's. Curious how it was determined infantry versus home guard? Especially from just a barreled action.

Out of the couple dozen K31's I have, only one scoped and I used the Graf's clamp on mount, left it all stock otherwise. I have 3 'u-fix-ems' that I got from AIM for $59. Mostly broken lumber and/or mismatched IIRC.

I'm a machinist, might try something similar with one of my junkers. And kudos for using a horizontal mill, not often seen these days.
View Quote


The line was a joke I made after bore  scoping. He bought two barreled actions of unknown origin. One looked great, the other was pitted. eroded crap.

Who knows how it got that way, could have happened here in the States.
Link Posted: 9/15/2021 5:28:40 AM EST
[#27]
Don't get no funny ideas !





Larry Racine was the gunsmith supplying re-barrel services. He is gone.
He did say, the earlier Swiss rifles were no more difficult to re-barrel than a 30-30.
Very nice work.
Link Posted: 9/15/2021 5:43:58 AM EST
[#28]
I'll be surprised if the final product shoots any better than your "good" gun.
Link Posted: 9/15/2021 5:46:25 AM EST
[#29]
This thread is easy to masturbate to.  
Link Posted: 9/15/2021 5:55:44 AM EST
[#30]
Skill and ambition...........both in abundance!


SUBSCRIBED
Link Posted: 9/15/2021 6:07:49 AM EST
[#31]
This here is a good thread. This place was once full of stuff like this.
Link Posted: 9/15/2021 6:19:28 AM EST
[#32]
Massive tag.  You guys that can machine metal are amazing!  Much respect.

I have two K-31s, paid $89 each back in the day.  They are stunningly accurate with GP11 ammo.

I can't wait to see what a purpose-built target model can do.

You guys are doing God's work, drive on!
Link Posted: 9/15/2021 6:23:06 AM EST
[#33]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I don’t have many gun regrets but, I regret not getting a couple of those when they were cheap and plentiful not that long ago.
View Quote

I wish I had gotten one as well....... damn accurate rifle
Link Posted: 9/15/2021 6:27:27 AM EST
[#34]
Excellent thread.   This will be fun to follow.
Link Posted: 9/15/2021 7:00:16 AM EST
[#35]
Link Posted: 9/15/2021 7:30:26 AM EST
[#36]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


The line was a joke I made after not scoping. He bought two barreled actions of unknown origin. One looked great, the other was pitted. eroded crap.

Who knows how it got that way, could have happened here in the States.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
The K/G11 actions are much easier to rebarrel, the cam action and lugs are in the back of the receiver.

Never once have I seen a bad Swiss bore, except on Vetterli's. Curious how it was determined infantry versus home guard? Especially from just a barreled action.

Out of the couple dozen K31's I have, only one scoped and I used the Graf's clamp on mount, left it all stock otherwise. I have 3 'u-fix-ems' that I got from AIM for $59. Mostly broken lumber and/or mismatched IIRC.

I'm a machinist, might try something similar with one of my junkers. And kudos for using a horizontal mill, not often seen these days.


The line was a joke I made after not scoping. He bought two barreled actions of unknown origin. One looked great, the other was pitted. eroded crap.

Who knows how it got that way, could have happened here in the States.

I’ve seen a few pitted K31 barrels—after the Stgw57 had been around a while the K31s had mostly become “corps materiel”, meaning they didn’t belong to anyone and no one was going to get fined for abusing them. Most of the beat up K31 stocks probably happened in the 1980s when they were being used as something heavy for recruits to carry around so they didn’t mess up their real rifles. After that they ended up in the official surplus stores for like 20 francs or something.
Link Posted: 9/15/2021 7:54:30 AM EST
[#37]
Great thread!!
Link Posted: 9/15/2021 8:02:35 AM EST
[#38]
Link Posted: 9/15/2021 8:10:36 AM EST
[#39]
Simpson's Ltd. has barrel gauges, they score their bores ( fair to excellent ) with them.
Link Posted: 9/15/2021 8:16:44 AM EST
[#40]
Wow! A gun related thread on a gun forum!
Link Posted: 9/15/2021 9:04:23 AM EST
[#41]
K31 barrels are widely available in Switzerland, but they’re 800 CHF, and there would be an importation fee to the US, so it rapidly becomes a cost-benefit analysis.

While there are collectors over there, for the most part the mindset is based on target shooting, so Swiss gunshops are frantically rebarreling and refinishing what we would consider to be collector guns. The only thing that helps with K31s is that most Swiss are uninterested in them, so they aren’t getting shot and rebarreled as much.
Link Posted: 9/15/2021 10:17:12 AM EST
[#42]
I've had several k31's.  They all will hold the xring in high power matches.   A 1954 Hammerelli gave me 2 gold medal scores at camp perry vintage rifle match's.  Lack of windage adjustment is it's only weakness.  But that doesn't matter if it's shooting sub x ring anyway.  Offhand is always the problem.  The only comparable vintage rifle I have is a Finnish M39.  It will group better than the K31.   Put the Garands sights on the K31 and you would have something.
Link Posted: 9/15/2021 10:48:38 AM EST
[#43]
OP, any particular reason your friend didn't want to go the bbl stub route, & just screw in a .308 bbl into a bored out 7.5mm bbl stub?  Seemingly would be a lot less work.
Link Posted: 9/15/2021 11:13:30 AM EST
[#44]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
OP, any particular reason your friend didn't want to go the bbl stub route, & just screw in a .308 bbl into a bored out 7.5mm bbl stub?  Seemingly would be a lot less work.
View Quote



Because he wants to do a 1.25 at the muzzle Krieger .

Can’t screw that through a barrel stub.
Link Posted: 9/15/2021 12:54:08 PM EST
[#45]
So my friend knew he wanted to go with a top tier barrel, but he wanted to retain the original cartridge so we didn’t have to alter the bolt or magazine in any way.

7.55 bore barrels aren’t on anyone’s list here, and he was already shooting .308 bullets through his
7.55 barrel anyway, a common practice amongst those who reload the Swiss cartridge here in the US, as 7.55 bullets are uncommon.

So the obvious solution was a .308 barrel.

Best deal was a Krieger, so that’s what he ordered .

Attachment Attached File
Link Posted: 9/15/2021 12:59:46 PM EST
[#46]
Now he needed a custom reamer to ream a 7.55 x 55/.308 cartridge to combine the Original Swiss case with the .308 bullet and barrel.

After many emails and phone calls, he went with a Mason reamer.

He sent them factory cartridge’s, and dummies loaded with the bullet he is going to shoot, in the necked up case, seated to the best length for the magazine.

Mason made the reamer to fit that cartridge, along with the gauges.

Attachment Attached File
Link Posted: 9/15/2021 1:01:29 PM EST
[#47]
Oh hell yeah
Link Posted: 9/15/2021 1:06:33 PM EST
[#48]
Join date, post count etc.

And wtf are you doing posting a gun thread in GD?

Sudscribed.
Link Posted: 9/15/2021 1:09:31 PM EST
[#49]
Holy shit is that rifle accurate.
Link Posted: 9/15/2021 1:11:08 PM EST
[#50]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Now he needed a custom reamer to ream a 7.55 x 55/.308 cartridge to combine the Original Swiss case with the .308 bullet and barrel.

After many emails and phone calls, he went with a Mason reamer.

He sent them factory cartridge’s, and dummies loaded with the bullet he is going to shoot, in the necked up case, seated to the best length for the magazine.

Mason made the reamer to fit that cartridge, along with the gauges.

https://www.ar15.com/media/mediaFiles/195613/07651793-8F44-4DEB-A7A8-513719B2E279_jpe-2091807.JPG
View Quote

How much do reamers cost that you have made specifically for a project?

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