Threading a Remington 700 barrel to fit a small ring mauser

[mickri]

This is probably my dumb idea of the month or even the year. I have been planning to buy Green Mountain barrels for my mauser projects. Green Mountain has been sold out of the barrels I want for awhile. In cruising the net looking for other options I see lots of Remington 700 barrels for sale. All the way from dirt cheap to expensive. The Rem 700 is a 1.062" x 16 tpi. Curiosity got me checking to see what is the minor diameter of a 1.062 x 16 tpi. Turns out it is 0.9876" The OD on a small ring mauser is 0.980. Here are drawings of the 700 and mauser.



The 700 shank is longer than the mauser even after you shorten it to remove the indent. Turn the shank down to .980 and shorten it to .645. Cut the 12 tpi whitworth thread and do a slight touch up with a chamber reamer for head space. I would be done. I know getting a brand new barrel is better. I am thinking of other alternatives that won't break the bank.

 

[mmcmdl]

I'm planning on threading the opposite end of the Rem 700 next week . .338 brake and possibly make up a can . ( just for hahas )

 

[pontiac428]

I don't see why you couldn't delete the "three rings of steel" bolt nose pocket from the Remmy barrel. The numbers don't add up on your diagrams, so you would have to deepen your chamber to get your headspace right. What you want to attempt here is perfectly fair game in gunsmithing.

 

[mickri]

The chamber would have to be deepened by around .090". This is a long shot. Impossible to know how good the rifling is or how accurate it would be. The barrel would have to be dirt cheap or brand new never fired. Otherwise I am better off with a new barrel. The Green Mountain gunsmith barrels cost $60 plus shipping. Hard to beat that price. More work in involved. Especially to contour the barrel to what I want. I like heavy sporter barrel contours and 24" length. To make the tapering easier I have thought about having a short 1.2" OD x 1/4" to 1/2" long ring (wrong terminology) at the receiver then go to 1.0" OD that tapers to around .70" OD at the muzzle. Like this.



Or do a more traditional taper like this.

 

[Flyinfool]

When I did my small ring Mauser barrel I just did a straight taper form the ring diameter to the muzzle dia that I wanted. I did it by offsetting the tail stock and having the barrel between centers. I then cut off the muzzle end to final length to get rid of any damage from the center and cutting the chamber removed all of the center at the chamber end. It ended up looking and shooting great.

Because of the length you have to have a super sharp cutter that is set up perfect and make really light cuts and use lots of good cutting oil or the barrel will flex away from the cutter, or worst case, climb up on top of the cutter. I still had to make a lot of spring passes with some fresh honing of the tool to get the middle to even out. Fortunatly for me I was planning from the start tot do a Cerocote finish so my final surface prep was with 80 grit sandpaper.

 

[mickri]

Contouring the barrel will be interesting. Lots of light cuts. I plan on taking 8 to 10 hours over several days to contour the barrel.

I watched one video where they made stepped cuts. The guy did a cad drawing that showed the depth of each. He finished it off with a sander to smooth out the steps. Seemed like a lot of math and very precise cuts. I read a post awhile back on PM where a guy described how he hung a piece of lead I believe over the barrel from the tool post to act as a follower rest. Other guys described using springs on the follower rest guides to allow the guides to move with the taper. Probably took some practice to get the spring tension right.

I have thought about doing a straight taper from the receiver to the muzzle. Seemed like that would be a very heavy barrel. Probably ok for the 222 Remington but I wonder about doing that on the 257 Roberts.

Of course I could just buy an already tapered barrel. Too many $$$$ for me and what fun would that be.

 

[mickri]

Found the old thread on PM about hanging stuff off of the tool post to help with chatter when turning a barrel. Interesting.

Quotes from PM

"If you run into chatter problems (likely) drape a leather belt over the barrel and hang some weights on it to dampen things. I've used this method many times on long, slim work and it saved the day."

"Forty years ago and old smith near Missoula, MT showed me how he used a half filled shot bag of 7 1/2 shot riding on the barrel to dampen the chatters, it worked well for him and I have used that method for years too. "

"If your worried about chatter when turning you can also cut a vee notch in a piece of 4x4 lumber drive a nail in the side opposite the vee, rest the vee on the workpiece resting the other end on the crosslide & hang a weight on the nail that way the weight is always opposite the tool. It was taught to me 30 yrs. ago by an old german toolmaker turning long thin wall alum. tubing. "

 

[silverhawk]

Deepening the chamber might be bad - there is an area of the barrel (I cannot remember what it's called right now, it being between the forcing cone and the rifling), that is unrifled. If you deepen the chamber, you could lose that, and it changes the characteristics of the barrel.

 

[mickri]

The chamber reamer should create the space of no rifling between the end of the cartridge and the start of the rifling. I can't recall what is called either and I looked at a chamber diagram this afternoon. The guys into precision shooting play with that space looking for better accuracy. All kinds of theories on whether the bullet should touch the rifling or have to travel a little bit first.

I will most likely never do this on my current projects. It was an idea that I wanted to explore.

 

[682bear]

Deepening the chamber might be bad - there is an area of the barrel (I cannot remember what it's called right now, it being between the forcing cone and the rifling), that is unrifled. If you deepen the chamber, you could lose that, and it changes the characteristics of the barrel.

We always called it the freebore... I'm no expert, but the few times I have chambered barrels the chamber reamer also machined the freebore.

-Bear