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K31 ACTION RE-BARREL COMPLETE

6K views 33 replies 11 participants last post by  2700fps 
#1 ·
I own the above that is worn out and pitted and want to replace the barrel in 7.5 x 55 Swiss NOT any other caliber. I reload and want it chambered specifically for the Berger 175 or Sierra 175 SMK.

There is no stock or hardware to put it back in its original K31 look so I am thinking of some type of bench rest/F-Class 300 yard stock.
It will have a K31 bolt.

I am now just beginning to start to get all my information together. Read on another tread that a reamer is NOT just a reamer when it comes to demensions. There are PTG reamers available both on EBay and from PTG.

Probably will go with a Bartlein or something similar. Have no information on Gunsmiths with 7.5 x 55 Swiss experience or stock manufacturers.

Thanks.
 
#2 ·
If you want to run a specific bullet and overall length you need to make up some dummy rounds and send them to a reamer maker. They can make a reamer specifically for your application. Anything else you buy off the shelf is a crap shoot. I used a PTG reamer to cut a chamber for a customer and it was not GP11 spec nor was it much good for the bullets he was using. Still a short throat type issue like you find with the GP11 chamber. On the other hand another customer wanted a barrel for his Desert tactical SRS rifle to shoot GP11 specifically. I sent some dummy rounds of GP11 to JGS reamers and got a reamer made for the Swiss military cartridge. Swiss guys get free ammo to practice with and he wanted his rifle to shoot that ammo. I made up a barrel for my rifle and I shoot 175gr Sierra Tipped Matchkings. The cartridge with that bullet and my load is very accurate. We've run it out to 2000yds and its amazing.
So the point of all this is that if you want to match your load get a custom reamer. I'm not sure if Dave Manson reamers will make one as I can't recall if I talked to them first before going to JGS or not. Dave is a good guy and makes great tools. JGS is also excellent. PTG isn't bad but they're frequently slow and difficult to deal with on custom stuff.

Next thing to be careful of. PTG sells CIP headspace guages and they are not right for the standard round. I don't know if there is a SAAMI spec guage or not but the go for the CIP was about 7 thousandths too long and the no go was longer.

Rebarreling a K31 is not a simple thing. The breech end of the barrel is very complex and difficult to machine. Most guys who rebarrel use the breech end of the old barrel as a bushing and screw the new barrel into it. I have no idea how that affects accuracy. I can't imagine having 2 sets of threads will help but maybe its not bad. Check on the Swissrifles.com site as there may be someone there who is gunsmithing the K31's.

Good luck

Frank
 
#3 ·
Thanks for the detailed response.

I had heard of using the old barrel and the bushing idea. Does not appeal to me!! If I’m spending the money it would need to be done correctly.

It looks like I will have to get my own reamer made to my specifications. As you are probably aware there is a difference between the 1911 chamber and the K31. The K31 being tighter I guess. I would not want a chamber based on the GP 11 as I only reload.
I received information I need to find a gunsmith with a 4 or 5 axis machine.

I have a lot of research to do!
 
#4 ·
Thanks for the detailed response.

I had heard of using the old barrel and the bushing idea. Does not appeal to me!! If I’m spending the money it would need to be done correctly.

It looks like I will have to get my own reamer made to my specifications. As you are probably aware there is a difference between the 1911 chamber and the K31. The K31 being tighter I guess. I would not want a chamber based on the GP 11 as I only reload.
I received the information I need to find a gunsmith with a 4 or 5 axis machine.

I have a lot of research to do!
I shoot with a Swiss Club and this conversion of barrels is a yearly discussion. IF and that is IF you can find a barrel from a name brand mfg that fits the receiver (note the diameter), take a quick measure for understanding. Take the last paragraph of AMAFRANKS message to heart. Then find somebody who can cut those angles without messing it up. Assuming your piggy bank is pretty full. Not to be negative but research this well or you may end up with a lot of disappointment. Just getting the old barrel off can be quite a feat. Plus, it is best to make a tool so you don't bend the receiver. Best to you on your ambitions and wish you the best in your project. The fellow out East who did most of this work quite well I have heard has passed. Sad and he was a true craftsman. He usually did two barrels as Frank said, why not? I would if I were spending this much I would want at least two. Best to you and if you do this please share your results, you will have many envious shooters looking. RJS
 
#7 ·
That is a really good question. I tried the CIP guages in my K31, K11, 1911, 96/11, 96 and 1889 rifles and its too long for all of them. So what guage? No idea. My buddies from Switzerland said they'd send me a guage but by the time it would have shown I was already done. I used factory loaded GP11 ammo as a basis for the chamber cutting and then fired some ammo I loaded using Privi Partizan brass along with some GP11 and measured the cases. All were within the specs I was using so all good. I will talk to Dave Manson and see if he can make me some guages based on the GP11 round. It looks like I'm going to be building some more barrels for the Desert Tech rifles so the tools will be used well.

As for the K31, you will find the chambers will vary slightly among all the Swiss rifles and if you want to run the original GP11 ammo you should use a reamer for that. Sounds like you're after something else and as you're building a custom setup you can have custom guages made along with your reamer. You can buy brass from Privi Partizan and its pretty good stuff. I was using it to shoot half inch groups at 100yds with the Desert Tactical rifle and was shooting it at 2000yds with good results too. There is also norma brass but its pricy and I find it soft and short lived. In any case you're pretty much on your own when you go custom and if you can afford to have someone make you a barrel from scratch the reamer, guages and dies should be done as well. CH4D makes custom dies and I think the major players do too. If you get JGS or Manson to make your reamer they can also make you a die reamer so the die and the chamber match up perfectly. The die reamer is just enough smaller to insure your resized cases fit your chamber. RCBS makes or did make a neck size die for the 7.5 as well though most find the K31 doesn't like neck sizing much. Your custom setup may be fine that way though. I use the neck sizer for the Desert Tactical but not for the Swiss rifles. They all get full length sized with the RCBS dies.

Hope something there helps

Frank
 
#12 ·
Short update.
Barrel was removed. The photos are attached. I am very confident this will get done.

Some dummy trunnions will be made before I order the barrel.
 

Attachments

#14 ·
Short update.

A couple of “dummy” tests have been worked on. The machine had to be reconfigured for metric threads which now is not a problem. All cuts except the graduated ramp can now be done by machine. Close to be given the go ahead once they have a completed trunnion to order my barrel, reamer, go/no go gauges and die.

Not decided on the barrel or bullet yet. Most likely a Bartlein, Shilen or Brux. The bullet will be a Berger or Sierra for sure. Not decided on the weight yet. Need to talk to them keeping in mind the GP 11 is 174 grs. Everything is custom regarding freebore, neck demensions etc. I will be using a 30 cal barrel with a twist rate to suit a 168 or 175 more than likely.

I also need to do some home work on the stock to use but there is time for that!

Thats it for now.......
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#16 ·
Very good progress made today. The first test example was finished.
Ordering barrel from either Bartlein, Brux, Kreiger or Shilen. Reamer from Manson o
Tool Machine Metal
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n Tuesday.

Bullet either a Berger, Sierra or Hornady. Probably 175 gr unless convinced otherwise.

Twist rate, lead, neck diameter etc needs to be decided. Hoping to get informational help from the various companies.

Also I need to decide on the stock manufacture.
If anyone has real world experience please chime in with any of these items.

Thanks
 
#18 ·
I think the original twist rate was just over 1-10. The barrel I'm using in my Desert Tactical is a 1-10 Douglas XX stainless and this year we made it out to 2500 yds with the 175gr Sierra tipped matchking bullets and the 175gr standard Matchkings as well. The tipped bullets do require less elevation to reach out there so the tips do decrease the drag. Probably not worth the difference in price for less than 1000 yds though. I did compare my load with original GP11 ammo at 1000yds to see what the difference was. What I found was that the GP11 needed 3.5MOA more elevation to reach 1000yds and that was about what I expected. I'm loading to a higher pressure with the Desert Tactical as the action is much stronger, being made for 63,000 psi 338 Lapua rather than the 44,000 psi spec on the GP11. My load is more in the mid 50,000psi range. Accuracy with both the GP11 and the handloads is excellent. I've not tried the Berger bullets but they should work well too. The shape is different than the Sierras and the GP11 though so overall length will change.

Your progress looks good. I don't think you'll go wrong with any of the barrel makers you mentioned. It appears your machinist is doing an excellent job of duplicating the breech area. Dave Manson is an excellent source for the reamers and very knowledgeable. We get a lot of reamers from him and have never had any problems.
For Stocks you might check with Richards Microfit. Richards Microfit Gunstocks They don't usually sell finished stocks but they do some custom stuff to near finish dimensions. Might be what you're looking for.

Keep the progress reports coming.

Frank
 
#20 ·
The parts have started arriving. These arrived the other day.
Kreiger barrel (5 months!!) and stock should be here next week.

The reamer will be tested on the aluminum trunnion that had the complicated cuts done before the barrel is touched!

Sorry. I don’t watch this site very often so have not had any updates. The work should go a little quicker now.
I will post any updates as the work progresses.
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#21 ·
What is so hard about machining that? I never saw one, but it sounded so complicated I was expecting something like an MG34 barrel extension. I almost never use gauges when cutting a barrel. Take a fired round and re-size it. Watch what you are doing and you will be fine. That way you don't need to worry about CIP specs.
Stocks--Try Fox-military.com for a repro
 
#28 ·
I have no doubt a K31 properly re barreled and set in a chassis stock will be a laser beam but the few great K31 barreled actions I've run across as projects run afoul because the chassis market is dominated by M700 Remington chassis.

I regret not buying those barreled actions to use as spares if I ever shoot out the barrels on my K31's, that was not a wise move on my part .

I would guess there are match grade barrels made in Switzerland and over there the re barreling of a K31 is not a huge issue. I wonder..maybe someone here knows....Can one send his barreled action to a gunsmith over there to be re barreled and be returned here ? Seems to me, if that were the case, I'd rather have that option to exercise.

I own several 1000 yd precision rifles but my gut tells me, the K31 with a awesome barrel on it , in a proper chassis would outshoot everything. Swiss tolerances...well, I think that makes a huge difference and that is why K31's are so accurate. Just my view of it all
 
#31 ·
I thought he did as well, and said so, but then could not find his obituary, even though I recall hearing his passing. So I omitted that.

Larry helped me a fair bit with Omark44 restoration, he was one of the few US gunsmiths that knew anything about them. Great guy to deal with.

The site seemed to have changes since I last was on it, which makes me wonder if the shop is still active not.
 
#32 ·
Some websites live forever. I tried to close mine down many years back and the host said they didn't know how to do it....the providers have changed over time and apparently some companies can't remove stuff from servers they bought years ago....


Progress is looking good and I think the K31 has some possibilities too.


Frank
 
#33 ·
Well the trunnion is complete.
Reaming next which should be quicker!

Then the stock…
Want to float the barrel but the barrel is extremely heavy. Afraid of stressing the receiver which was not made for such a heavy barrel. May put a bedding block just forward of the end of the receiver.

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