Which magazine box should be installed when converting the g-series M-70 S/A from 22-250 Rem to 6mm Remington which would allow adequate COAL and feeding?

Thanks

I own a Model 70 short action rifle, and I also have Winchester catalogs for the years that the short actions have been manufactured.

It appears that the Short action was intended to work with variants of the .308 case, as it has been chambered in 22-250, ,243, 7-08, and the caliber that I have, which is .308. I cannot find a catalog that lists the rifle as being chambered in 6mm Remington.

22-250 case length is 1.912 and oal is 2.350.
3.08 is 2.015 and 2.810, 7-08 is 2.035 and 2.800 and .243 is 2.045 and 2.710.

In looking at my rifle it appears that the way Winchester handled the various cartridge lengths was with a spacer located at the rear of the magazine box. It also appears to me that one would be hard pressed to fit a longer magazine box in the rifle. But the 6mm Remington is 2.233 and oal of 2.825, which is only 15 thousandths longer than the .308.

The spacer located at the rear of the magazine box could possibly be smithed by a talented individual in order to lengthen the space in the box for a slightly longer cartridge.

The only thing I would not comment on is whether you would have any difficulty cycling cartridges because of the geometry of the top of the magazine box, which has obviously been set up for the .308 family of cartridges.

Why not just look for one that is factory chambered for the .243?

But IMNSHO, the best 6mm Rem., if you are building one, is throated for an OAL of 3".

Clarence

The 308 length Mod-70 can be a good candidate for a 6mm Rem, Roberts or 7x57 but does require some effort in the form of removing the cartridge block from the magazine or making a new box and follower. A 7x57 will just fit into that action with no length alteration required on the underside but will require the ejection port to be lengthened to the rear. In doing so you loose the leading scope base screw hole. If you can make a box and alter the action re-drilling a new hole is going to be pretty easy I'd guess.

My daughters 260 is done in this matten and is a great little rifle with plenty of room ahead of the bullets to chase the rifling. I have converted a 2 other 308 length M-70's in the same fashion.

The major problem you can run into is in the actual action. Winchester re-introduced the 308 length Claw Extractor model calling it the Compact and early on these actions had both left and right feed rails solid or the same length front to rear. This early action is the one you want.

I can only guess that when the Short Mags were introduced that they a lot of feeding issues and corrected this by cutting in a notch on the non ejection port side of that rail that is approx. 1/2" in length and 3/16" " in depth to allow those fat cases to roll out of the magazine and up through the rails. While this works for the short mags it's a major pain in the ass with some 308"s and 243 sized cases if you're trying to get a 308 length case to feed really well as this notch allows the case to release to quickly and allows the case to leap ahead of the bolt face and extractor. Most folks never have noticed this so it rarely comes up in conversation.


Finding Compacts that don't have a notch is a bit of a mission and a reason why I don't offer to build any Legends for these cartridges.

But a better 7x57 platform would be hard to find in regards to length, weight, etc. But it's going to take some work.

Thanks for knocking that one out of the park, D'Arcy! This basically answers a question I recently posted in the gunsmithing section regarding converting short action model 70 classics to intermediate. Winchester also made their basic "Classic" featherweight in a short action well before the short mags came out, in 2001. If your theory about the feed rails is true, then quite a few short action M70 Classic Featherweights made before 2001 are out there. The "Classic Compact" model production was much less, but it sounds like pre-2001 short action featherweights should have the proper feed rails to allow your modifications.

Could someone take pictures of this? For aid in buying?

quote:

Originally posted by RyanB:
Could someone take pictures of this? For aid in buying?

Yes, a picture of both short action M70 feed rail types from actions chambered in 308 based cartridges would be awesome.

Thanks bunches lindt2! That serial # does seem like very late production Model 70 Classic. How hard would it be to fill that notch with some judicious welding and filing? Finding an earlier action would be the best way to go. Those little compacts are sweet guns. I had the chance at a couple in 7mm-08 years ago. Wish I'd bought one.

Matt I had to fill the notch on another 260 Rem I put together and did so with a lower temp silver solder and a piece of 4140. Once the notch was filled the rounds coming off the left rail feed perfectly. Until this was done however the round would release way to soon and ahead of the bolt face about 85% of the time.

As stated above this did not happen on every action that I got to run some dummies through but enough times to convince me that I needed to be much more selective in choosing a non notched action when looking for one.

I might add, and I think Mr. Echols would attest to this, that if you are going to go to the trouble of "fixing" that notch and putting on a new barrel you might also consider having the trigger reworked. They are sloppy on this rifle, and for utter reliability a new pin should be installed.

Also, if you get the compact, plan on adding a thick recoil pad if you do not want to have a new stock made for it. Otherwise, the stock is a bit short.

All in all a very nice little rifle that you can still buy for a reasonable price. And I might add that if you have a wife, daughter, or girlfriend that likes to hunt one of these classic compacts would fit the bill very nicely.

Here's another rail setup that has also has a relief in the left rail but it's toward the front and not nearly as pronounced.

This is an SC M70 action originally in .243Win and rechambered to 6.5CM. I swapped out the .243 box for a WSM box for length and had to tweak it by pinching the rear of the box and bending the top lips slightly inward.

The whole action is incredibly slick and it feeds so well that it's almost impossible to tell the difference between cycling the bolt with or without ammo. It's not 100% as the bolt will occasionally override the first round of five but the spring is rather soft and it's a "range toy" rifle and not a DGR.

FWIW, it's an honest 1/2" rifle and all I did to the action was measure it. Jigged it up in a truing fixture and wasn't able to read any off-perpendicularity of the receiver face and although the threads showed .003" TIR from the bolt race, they appeared to be parallel to the race. Both lugs showed 80% or better contact out of the box so I fit the barrel, bedded it in a McMillan M40 and went to town.

quote:

Originally posted by DArcy_Echols_Co:
Matt I had to fill the notch on another 260 Rem I put together and did so with a lower temp silver solder and a piece of 4140. Once the notch was filled the rounds coming off the left rail feed perfectly. Until this was done however the round would release way to soon and ahead of the bolt face about 85% of the time.

As stated above this did not happen on every action that I got to run some dummies through but enough times to convince me that I needed to be much more selective in choosing a non notched action when looking for one.

D'Arcy,
Thanks for all the advice D'Arcy! I had asked about the plausibility of modifying short action Model 70's to handle intermediate length rounds, in the gunsmithing section, and wondered if intermediate mag boxes from Montana Rifle Company might work in such a conversion. MRC says their short/intermediate action can handle cartridge OAL of 3.15". I do not know if the footprint and hole spacing of the MRC short/intermediate is the same as the SA M70 (MRC uses that same action for short and intermediate rounds). As most folks around here know, MRC basically took the model 70 Classic and changed the breaching method and bolt release to come up with the 1999 standard action. Did they do this with the M70 classic short action as well, and basically did, in factory form, what modifications you have done to Short action model 70's? Thanks again!

Out of curiosity, I just called up MRC. Turns out that their short/intermediate action basically is, in factory form, what Mr. Echols short action model 70 classic modifications accomplish (other than the "Mauserchester" aspects of their action). Same footprint and guard screw spacing.

If your looking for a short action model 70 without the cutout in the left rail this might be one.

http://www.24hourcampfire.com/..._Model_70_Featherwei