Switch Barrel Mauser?

[leadman]

I have a 1893 Spanish Mauser that has a very worn 7X57 barrel on it. A 175gr Rem bullet is barely in the case to almost touch the rifling. Cast is minute of 55 gallon drum.
I have a 7.62X39 barrel and feed kit on the way. I also have a '98 Mauser barrel in 25-06 in the garage. This could become a 257 Roberts.
I got the idea for part of this when talking to a guy that rebarreled benchrest guns. He said the barrels do not necessarily needed to be cranked way tight.
I was thinking of installing the barrel and checking headspace and doing what was necessary there, then putting a witness mark on the action and barrel. Mark the barrel for milling flats just in front of the action for an open end wrench. Then reinstall the barrel and drill a hole at the front of the action on the bottom that just goes into the barrel for a setscrew.
A Leupold type sight base would be installed on the action. A scope would be sighted in and one of the windage screws loctited in place. Then if additional barrels were fitted in the same method a scope could be installed and sighted in for the barrel.
To change a barrel you would remove the action, take out the setscrew, turn out old barrel, turn in new barrel, change mag spring and follower if needed, tighten the set screw, change the scope, install in the stock.

What are the flaws in my plan?

[Frank46]

Head space comes to mind. You would have to have your bolt to have the proper head space for each barrel you plan on using. I would also use molycote or a similar lubricant (neverseize) to prevent easy installation and removal of the barrels. Either one will prevent galling and seizing between both the threads in the barrel or receiver. Don't know where you'd get the molycoat but never seize should be in just about any auto parts store. Bench rest shooters do not torque their barrels like you find on old mausers. They use an aluminum barrel holder and a tool also made out of aluminum. Back end of the tool has a square machined on it and the handle fits over this square to provide the necessary torque to unscres the barre. Reid Coffield of the shotgun news did an article last year on swith barrel mausers. Hope this helps. Frank

[leadman]

The same bolt will (should) work with the 7.62X39 and the 257 Roberts so as long as each barrel is headspaced properly that should be ok.
I have lots of antiseize, was a diesel mechanic in Michigan for many years. I also have spray graphite that is a very good dry lubricant.

I'll have to see if that article is on-line.

I had an old Mauser rebarreled by a locate gunsmith and it started seperating cases at the range one day. I found the barrel had come loose and unscrewing. I hand tightened it and shot some more with no problems. I did buy the tools and tightened it later though.

I was thinking about this project last night then read a post on a local forum about the new T/C Dimension switch barrel bolt rifle. The concept is pretty neat. don't know what the price tag is though.

[jblee10]

I've done switch barrel Mausers and Savages. I don't think it is worth the effort. I ended up looking for actions and stocks on both brands. The problem is change of accuracy and sight settings. Mausers are great. On a 94 or 96 Mauser I would build a nice 7x57 (or my personal favorite, 6.5x55). Stick with one caliber and shoot the heck out of it. By the way, I am still looking for one 94 or 96 Mauser action, one 98 action and a short action Savage.

[leadman]

I bought a 1909 Arg barreled action many years ago. barrel was a sewer pipe but the receiver sight on it was worth what I paid for the barreled action. Plans are to barrel it this week with a 6.5-06 barrel and put it in the McMillan stock I have.

[flounderman]

I have a small thread from a turk, 8mm, 28 inches, real good barrel, military sights, cheap. threads are the right size for the small rings, don't know if the headspace would be right. could be a screw in.

[HollowPoint]

I just recently re-barreled my old No.4 Mk1 Enfield using the Savage-Barrel-Nut method with the idea of using it as a "Switch Barrel" rifle. For all intents and purposes I think it turned out well but, after having done so, I'm now looking for another donor Enfield with which to build the 45-70 I intended to use as the barrel to be switched with this set up.

The "Switch Barrel" sounds like a good idea; and it actually is a good idea but, a more convenient idea is having two different rifles in the calibers you were wanting to switch back and forth to. This allows one to skip the "Switching" step and just go directly to the load and shoot step. (at least in my case)

Since it's your rifle, I say make it the way you want to make it. As long as the cartridge and the action is rated to withstand the pressures generated by your chosen chambering, you should be OK.

Best of luck with your project. I hope you'll post some pics when you're done.

HollowPoint

[MBTcustom]

I got the idea for part of this when talking to a guy that rebarreled benchrest guns. He said the barrels do not necessarily needed to be cranked way tight.
The thing about the tightness is, if you are using a righthand twist barrel, the boolits will tighten the barrel to the threads (the heavier the boolits the tighter the barrel). If you are using a lefthand twist barrel, you are going to need a lot of torque to prevent the barrel from being unscrewed by the boolits. Thats the real reason why most barrels are RHtwist. It has to do with the threads a lot more than the flight of the boolit. The British Enfield used a LH twist barrel to compensate for the action because it was stronger being twisted one way than the other. However, they still had RH threads on the barrel, so the British enfields are always trying to unscrew the barrel from the action. They dont do this of course, but thats because they torqued their barrels to 125 Ft/Lbs!
I also wanted to let you know that if you are going to do this, be sure to break in the threads real good before you call a certain spot good. I have found that my barrels screw in further and further as the threads crush properly. As a thread is torqued for the first time, there are only two threads that are actually touching. As the thread is worked, the bearing surface of the thread gets larger and larger creating a more positive stop. NASA actually tested this and created bolts with floating threads. The problem was that they would torque the bolts down on flight hardware, but after making it to space and back, the bolts would not be tight anymore. All the shaking and temperature cycling (much the same thing that a barrel goes through) would peen down the two contact points on the bolts and they would "loosen". The ideal solution would be to make the threads tight and lap them together so that they mate perfectly over all the threads. That idea is time consuming and full of its own troubles.
I would think that the best way to do this would be to get all the barrels you want for the project and thread them to exactly the same pitch diameter measured by wires. Screw the barrels one by one onto the action to a predetermined torque. Do it about ten times. Then chamber the barrels and set the headspace for each one. That would insure that they all act the same way and stop consistently at the same point every time, and If you use one a lot more than the others, it wont change the way the other barrels match up.
This is all just theory on my part based on information that I have gathered. I had a very similar idea in mind at one time, but I never followed through with it.
Its just something to think about, and I hope it helps.
:drinks:

[MBTcustom]

A slight modification to my previous post.
I have recently been made aware that it is not necessary to use any real amount of torque to install a barrel. Since a RH twist tightens the barrel onto the action, it is not necessary to do any more than bump it closed. So it may not be as necessary as I originally thought to break in the barrel threads. Sorry for the misinformation.

[leadman]

I may not do the switch barrel part until a later date. I have decided to buy a new stock and trigger for this gun and a new trigger for another Mauser I am assembling. I will still have the capability of adding barrels later.
I disassembled a Turkish 98 I put together many years ago after having a gunsmith put a barrel on it in 6.5-06. The barrel came loose while shooting it. I decided to investigate why the bolt is kinda wobbly when opened and found the top guide rail is much too wide. I had bent the bolt handle and shaped it so the number is gone and I don't remember if it matched the receiver.
I tried the bolt out 1909 Arg that I am rebarreling to 25-06 in the receiver and it is tighter but not like it should be. The bolt for the Turk is a different length than a standard 98 so I may have difficulty finding another.
I did find some 98 receiver complete on Gunbroker for a decent price so may buy one of these.
More fun.

[leadman]

My Mauser project is not going well with the Numrich barrel in 7.62X39. The first new barrel had an 1/8" wide ring that measured .308" one inch from the muzzle. the reat of the barrel measured .310" to almost .311". This barrel had light rusting in the center of the barrel. Called Numrich and sent it back and ordered a second barrel.

The second barrel had an identical ring in the barrel plus a large amount of rust in the center extending to about 3" to 4" from each end. I cleaned it out but without a bore scope I can't tell if it left pitting or not. I will call Numrich Monday.

[MBTcustom]

Hmmm. Thats a big NG (not good)
If you will pardon the question, Why are you trying to use the original wartime toiletry instead of new Adams and Bennett barrel blank stock? The barrel blanks are about the same cost I think and with the A&B, you get a brand new, good quality pipe that will give sub MOA more often than not.

[leadman]

The barrels from Numrich are brand new barrels, short chambered and the exact dimensions externally as the A&B F14.

I think I have the problem figured out. My son brought over the Mauser 98 in 308 Win I did for him along time ago. It has an A&B F14 countour barrel on it. I compared it to my barrel from Numrich and the only difference is his barrel is shorter by about 1 1/4", exactly the amount I need to cut this barrel off to remove the "ring"!! Both are listed as having a 21" barrel but his is just under 20".

I'm going to call Numrich in the morning and if they have no good update for me I will just cut this off and call it good.

Another reason to not use an A&B barrel is Midway does not offer one in 7.62X39 with a
.310" or .311" bore. The only other barrels with the proper bore I found were over $300 and not threaded or chambered.

[leadman]

Well, I now know why there are not many of the Mausers converted to 7.62X39. This does not feed well at all and when extracting the case it comes loose from the bolt face. I did buy Numrichs' feed kit but it is not designed correctly.
It actually feeds better with the original follower and spring but there is so much extra length in the magazine for the cartidges to slide around in they don't stay stacked properly.

It appears to correct the feeding I will need to weld up the feed ramp and the rails on the action above the magazine. The cartridge is coming up out of the magazine box too soon and points to the side too far due to the shoulder being so much smaller than the original 7X57 case.

I may buy another barrel in 7X57, or rechamber this one to 7.65 X 54 Arg. I'm set-up to cast and load for both.

This is getting to be a project that is dragging out too long.

Has anybody here tried welding the rail and the feed ramp?

[flounderman]

if you look part way up the bottom side of the rail you will see a shoulder was put there to steer the case away from the rail as it was pushed forward. if the case is coming out too soon, the shoulder is too wide, and that is why it doesn't feed straight. the case is too short. taking some off the shoulders would delay the case coming out. it might correct the problem but work slowly. what it needs is for the shoulder to be moved closer to the chamber but taking some off the shoulder might work. as for the case not staying in the extractor, is the rim thinner than a normal 7mm or 8mm. is it as wide? if it isn't as wide as the bolt was made for, it can't hold the case head against the other side of the bolt face and just falls out.

[leadman]

The 7.62X39 is smaller in the base but I made some progress there by trimming the inside of the extractor so it fits over more of the bolthead. If I can't trim enough I may weld on another piec and shape it to hold the 7.62X39 case.
I also was also remembering an article I read, think it was by Ackley on feeding from a Mauser magazine.

I took some of the metal duct tape with the sticky back and put 2 layers on each side of the receiver above the magazine and extended up the hole so it made the inside of the hole smaller. The cartridges fed perfectly from the magazine!!! Two layers of tape measured .008" thick.
I have to find some shim stock .008" thick to make pieces to either solder or expoxy in place. If I can't secure it adequately to the receiver I may extend the metal shim all the way to the bottom of the magazine. Will have to see how it works out.

[MBTcustom]

I took some of the metal duct tape with the sticky back and put 2 layers on each side of the receiver above the magazine and extended up the hole so it made the inside of the hole smaller. The cartridges fed perfectly from the magazine!!! Two layers of tape measured .008" thick.
I have to find some shim stock .008" thick to make pieces to either solder or expoxy in place. If I can't secure it adequately to the receiver I may extend the metal shim all the way to the bottom of the magazine. Will have to see how it works out.
See, thats exactly why I want a TIG welder! Those feed lips are like the edge of a knife and they are so critical to reliable feeding. That is the place I get stuck in the mud with every Mauser caliber conversion. If you got the welder, no problem! You can message the edges in or out and find out what the cartridge likes. As it is, I have a build going now that is going to sit right where it is until I get that welder. Of course, for me, I can justify it as a business expense some day, but even then, those mothers are expensive!
I like your idea with the shim stock. I tried that on my build, but I couldn't make it rigid enough to know for sure if it was working or not.
Have you given any thought to blocking up the magazine to make it hold the shells better?

[Nobade]

Score High benchrest followers make this kind of thing a lot easier. Of course it's then a single shot, but for the range it works great.

[B R Shooter]

I would like to comment on a couple things that have been discussed here.

"Switch barrel": It's done all the time, it's nothing new, and it's easy. If you have a Remington or similar that uses a sandwiched recoil lug, it takes a bit longer, but still easy. Chambering multiple barrels for one action should be no more difficult than chambering one barrel. Each action I work on, I record the serial number and I take measurements of the barrel when the first barrel is complete. I can then use those measurements and chamber barrels from then on and not need the action, which even includes the timing of the barrel pulling up in the same position each time. As long as the cartridge bolt face is the same, it will headspace and tighten the same. Plus, switching from one barrel to another, within reason of cartridge, the impact will be within a couple inches. One or two shots and you're good to go.

"Torque": A barrel needs to be torqued fairly well. I don't think anyone relies on the twist of the barrel to tighten the barrel. Look at what you have. You have a barrel that is over 20" long being held by and cantilevered by about 1 inch of threads. That's a lot of overhang. The barrel must be tight against it's shoulder in order to dampen the vibrations and hold point of aim. With any decent barrel vise and action wrench, you should easily be able to get at least 80 foot pounds of torque, 100 is better. Lube the threads, and lube the shoulder mating surfaces.

[MBTcustom]

"Torque": A barrel needs to be torqued fairly well.
There are some gunsmiths that would disagree with you on that point. I understand about cantilevering and all that stuff, but excessive force is excessive force. Sometimes, just because it seems like a good idea to scronk the living schite out of it white knuckle tight to a silverback gorilla, doesn't mean that you should.
I'm still figuring out where I stand on this point. However, I dont whack my molds with a piece of timber anymore, and I always thought that was necessary. I think there are a lot of things in this sport where we are a little nervous, so we substitute brawn for the brains we lack. (That comment was not directed at B R Shooter or anyone else, just a figure of speech!) Just saying that sometimes less is more.

[gnoahhh]

Another thing to consider is the bedding of the barrels in the forearm. Using two barrels with the exact same contour makes it easier. Not such a big deal if one is free-floating them, but what if one needs a pressure pad out near the tip for best accuracy and the other one doesn't?

[leadman]

I probably won't make this a switch barrel gun now that I have to shim the feed area of the receiver for the 7.62 X 39, unless I install a 22 or 6mm PPC barrels. These would be handload only as factory is too hot for a '93.

I have a left hand Savage bolt gun that I can make a switch barrel much easier than this gun.

Or I could buy a new T/C Dimension rifle. Do they come in left hand?

As far as torque, 100 pounds is not much for threads this size. When I was working as a diesel mechanic 300 pounds on main and head bolts was the norm. Some head bolts were #480.

One of the benchrest guys here can change a barrel on his rifle in a matter of minutes with a rubber strap wrench, so there is not much torque involved.

[flounderman]

you can probably build up the rails with jb weld if you get them degreased. seen some new product jb makes. guy stuck his door mirror back on with it. said the stuff is the real deal.

[B R Shooter]

One very reputable source for the barrel torque issue is Harold Vaughn's book, Rifle Accuracy Facts. Every top benchrest gunsmith I know and have talked to agrees with the need for a decent torque for top accuracy.

Yes, you can change barrels in just a few minutes, I've done it between relays!

[felix]

Enough to make the barreled-action act as a unit in creating consistent vibes. Absolutely no more torque required. Verify with transducers when in doubt. Attatching the works, including scope, to the stock is as important. Glue-ins tend to eliminate the torque question for this instance. ... felix

[B R Shooter]

Enough to make the barreled-action act as a unit in creating consistent vibes. Absolutely no more torque required. Verify with transducers when in doubt. Attatching the works, including scope, to the stock is as important. Glue-ins tend to eliminate the torque question for this instance. ... felix

"Enough to make the barreled-action act as a unit in creating consistent vibes. Absolutely no more torque required." And what value of torque would that be? 50, 75, 100 foot pounds? Have you read how extensive the testing was done in Vaughn's book?

"Attatching the works, including scope, to the stock is as important. " Attaching the scope to the stock?

"Glue-ins tend to eliminate the torque question for this instance." Are you saying a glue in eliminates the need to torque a barrel?

Glue ins are used in 99% of the benchrest guns today. The need to torque a barrel is just as important in these guns as it is in a hunting gun.

[felix]

Have you read how extensive the testing was done in Vaughn's book? Ans: No, Need to know how the "threads" are machined to synthesize a valid conclusion.

Attaching the scope to the stock? Now, that idea of yours would be something to investigate for pure accuracy systems. Some black guns are leaning into that realm, aren't they? Consider the computerized sighting systems, if and when they are allowed in BR. My sentence as it stands should have included parentheses instead of commas. My bad.

Are you saying a glue in eliminates the need to torque a barrel? No. Again, my bad. My sentence as it stands should have made the "instance" more pointed into the direction of attaching the stock to the action via nuts and bolts.

Something to keep in mind, however, is that truss systems have been the principal technique to engineer out vibes, or at least to have them cancel each other within a cantilever design.

... felix

[B R Shooter]

As another point of reference, do a search for "Varmint Al". He has done very extensive barrel vibration testing.

[leadman]

I do know when a barrel comes loose, as one I had a gunsmith install did when shooting the group size changed very little until I noticed the bulge on the base of the case. I turned the barrel back in tight by hand and continued shooting for a few more rounds with no problems. Not saying that was an ideal situation, far from it.

I have epoxied the shims in place on the receiver and it feeds great from the right side, not so well from the left side. Didn't see that that shim had pulled away just a bit on the left side so will have to redo that.

I'm debating which way I want to go to get the extractor to hold the case after it is out of the chamber. After the case is out it drops off the front of the bolt because the extractor is not long enough to hold the case to the far side of the bolt face. I have ground down the areas that ride on the side of the bolt some and it is better but am about out of material I can remove before the extractor hits the locking lug.
I have 2 extractors to play with so may try welding up one of the claws and grinding it to fit. Would rather weld on the extractor than the bolt face.
Any ideas??

[MBTcustom]

That sounds like a good idea, would you consider posting some pictures? some of this would be much easier to visualize with a photograph.

[leadman]

Well, have not gotten around to working on the Mauser. Instead been catching the heck out of crappies! Been a very good spring for us, 3 trips of 5 or 6 days each, relaxing, fishing, doing nothing. Caught 300 fish with most being crappies. Before someone gets excited there is no closed season or limit here in Az on them. And we eat everything we keep. Enough on the fishing.
Had to pull the rear springs off the motor home today and will take them to be repaired. The rubber bushings are toast. Extremely hard and large chunks coming out of them.

Been thinking on what to do with the extractor on the Mauser and decided I may heat the claw until it is red and do a little hammering on it to make it long enough to grab the case. Not sure what it will do to the temper but I have 2 extractors so I guess I will find out.

[MBTcustom]

Be sure it is properly supported when you go to beating on it! Usually there is a very specific radius cut on the inside of the extractor arm. You dont want to get that flattened out or its going to look like dookie and the claw will never be able to reach far enough around the face of the bolt to grab the case rim. If you need help with a round piece of steel to use for an anvil, I can certainly hook you up in short order.

[leadman]

I was thinking on using one of my chisels clamped in a vise and use the head ground to fit the bend in the extractor. I will then use a flat punch that is for an air hammer to place against the face of the claw so I don't end with hammer marks in the face. I just want to extend the reach of the claw and do hope to not distort it.

Thanks for the offer of the steel.

But today I took the springs from the motor home in and should have them back this afternoon. Have to save some energy up to be able to work in the 102' heat anticipated for today.

[FrankG]

I used my wirefeed welder to add a bead to lip of claw and reshaped to grip the lil rusky cartridge . I used a piece of brass to back it while doing the build up weld.
I also made a block from aluminum to add in back of mag box , shortened follower front and rear along with clipping spring length top and bottom legs to fit the modded follower.

[leadman]

I had heated the claw on one extractor and peened it so it gripped the cartridge case. It worked but since I did not reharden it it bends easily.
Midway has a blank ectractor for a 96 Swedish but don't know for sure it will work on my 93. I posted in the military rifle section asking for the extractor dimensions for the 96.

I did shoot it today with Tula factory ammo. The SP ammo was ok, but the second shot of the HP ammo was not. The bolt would not open until I used a deadblow hammer at home. The velocity of the 123gr bullet was almost 2,600 fps! Normal is less than 2,400 fps. The primer was flattened so much it was starting to go between the case head and the bolt face.

I've decided to try some American ammo and also load my own. I had wanted this rifle for shooting the cheap ammo when I hurt to much to load my own. Do not want to run the risk of blowing the gun up though.

[bob208]

i saw a picture of a mauser 98 take down rifle.also seen some 03's made the same way the stock is cut offat the reciver ring a steel plate added to the front recoil lug the forarm is treated much like a winchester takedown rifle. that work done it would not be hard to make up new frontends in other calibers much like take down winchester 94 and 95"s

[leftiye]

As for that feeding problem with 7.62X39, Take a look at shortening the follower from the REAR, and put a block in the rear of the magazine box. This will in effect make the feed rails narrower because the ctgs will be dealing with the front of the magazine where the rails are narrower.

[Multigunner]

The large ring Mauser was a development of a quick detachable barrel take down rifle designed in 1896. They had found that small ring actions were not a good platform for the interupted thread QD barrel set up, the large ring and shank was to provide more meat to the system. They then figured this large ring without the interupted thread would provide a better platform for the higher pressure loadings of the newer military cartridges like the 7.92.

[joatmon]

The 96 extractor is long enough for the ruski convertion!
Aaron