Old M70 why'd they do that ?

I've been going through the family heirlooms and making needed notes and doing the things that decades of use and disuse need to be done . Of course there are diamonds that just need to be dusted of and wiped down and there are a few that saw a lot of seasons a few shots and haven't been touched in a decade .

The latter is such the case in a 1957 purchased new in 1958 M70 06' . It had about 25% of the stock finish completely gone and 1/3 or more in various states of not stuck to the wood at all .

In the course of this I was reminded that of all the unique Mauser lended designs on hand it is the only one with 3 action screws and one in the barrel .
Blasphemous as it may be we have 2 that borrow some that have a single lug 1 screw and a barrel band which was a design success coming out of WWII . Dozens of 700s , 95s , and 98s we've had had only 2 action screws , even the Italian and Japanese cousins only had 2 screws . The possible exception would be the 03' or 1917s but not having had a complete example or that much inspection time I can only guess at the barrel bands .

So was there a reason for the 3rd action screw ? Added insurance to avoid patent details ? Just a work around for the magazine floor plate ? Does it really make a difference in action stability ?

The barrel screw I can see relative use but I have seen more rifles without the screw either rebarreled or restocked than with . So is the M70 Mauser like and wants for a free float or like the 03 and Mannlicher wants to be held down or tip pressured ?

That's a lot of questions ...... Free discussion appreciated .

Tip pressure and very modest torque on that middle screw.

My Father was an Engineer and sometimes I have a bit up tongue when I get home from working with a few, another discussion. That said, maybe the thinking was to play with fore end pressure and decades later we may have a better understanding of barrel harmonics. Look at how far metallurgy and the machining process has evolved and the unknown amount of rounds reaching those conclusions. I am positive some here have been over a bad barrel and watch it head for the weeds heating round after round, hard to fix a bad barrel but some can be calmed down to minute of deer for the Bass Pro hunter maybe. In my lifetime as a child pie plates were used, now it has to cut 1 MOA or it's a dog. But you can have a good one out there in free air forward of chamber and it keeps dropping them in there. Way back think I remember articles referencing armorers fixes for the front ends of SMLE's, the action shimming and front end work of the Finnish chasing barrel/accuracy wandering issues. Lots to ponder, excellent mental volley ball!

No real idea on the three screws for the trigger guard, it seems more complicated than necessary when you had forty years of two screw Mausers for an example of what worked.

Considering the Model 70 Winchester was designed in the 1930's, well before epoxy was used for solid bedding, and people thought an air gap for a fully floated barrel was poor workmanship; I believe the forearm screw was a simple somewhat cost effective way of marrying the forearm to the barrel without unsightly gaps.

I have inletted forearms to the barrel on a few rifles, to prove I could do it. I have also went back an floated a few after shooting some of them.

Start with a good barrel that is precisely fitted to the action, and its kind of hard to get one to shoot poorly.

Robert

I have no idea why they did it but can say that overtightening the middle screw will play havoc with accuracy, at least it does in all 6 of my model 70's.

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Originally Posted by stubshaft

I have no idea why they did it but can say that overtightening the middle screw will play havoc with accuracy, at least it does in all 6 of my model 70's.

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I also learned, quite by accident, that a loose middle screw would give the most amazing 4 inch horizontal spread at 100 yards. After tightening, the gun went back to 1 inch or less groups.

"So was there a reason for the 3rd action screw ? Added insurance to avoid patent details ? Just a work around for the magazine floor plate ? Does it really make a difference in action stability ?"

The middle screw is there to simply hold the front of trigger guard in place and prevent the magazine spring tension from pushing it down and unlocking the floor plate.

On the standard weight Model 70 with the boss on the barrel with the barrel screw, the traditional wisdom back in the day was to remove that screw for best accuracy.

The model 54 Winchester had the same 3 screw setup if I remember right. So at the time I guess Winchester figured it was logical to carry on the same system. Have a 54 action but can't get to it to confirm the 3rd screw. The 54 action had a stamped combination trigger guard and floor plate. But where the forward screw is located is in a different location that the model 70. Frank

The middle screw on a Tang safety Ruger 77 is there to help crack the trigger guard(pot metal) when you over tighten it! After I got the replacement and BARELY tightened it, the rifle started shooting a lot better.

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Originally Posted by Mk42gunner

No real idea on the three screws for the trigger guard, it seems more complicated than necessary when you had forty years of two screw Mausers for an example of what worked.

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The Model 70 had two-piece bottom metal, separate TG's and floorplate's - ergo the need for 3 screws there.

Military Mauser 91/93/94/95/96/98's all have the TG & floorplate made enbloc (IOW a single piece)

The Winchester Model 70's 4th screw (through the forend, into the rear sight barrel boss) was thought to be needed during that time frame, for best accuracy.

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As to the forend screw. . .

The M70 showed up when elements of the Lee and P14/M1917 Enfields were still fairly cutting edge. The Lee was something of a marvel of rings, springs, etc... to stabilize a thin, portable barrel against the abuses of military service. The 14/17 went simpler, and engineered the forend of the stock to put upward pressure on the muzzle when the action was snugged down. By the time the Brits got around to updating the Lee No.1 MK3 to the No.4 pattern in the later '30's, they were cutting the wood to apply about 5 pounds of upward pressure at the muzzle when all the bits were locked into place. The standard Remington 700 sporters from introduction in 1962 to present day STILL use this method to put a pressure point at the forend tip.

So there was a fair amount of conventional wisdom at that time that said this was necessary, and there are plenty of bughole groupers out there that do this. It is worth remembering that free-floating is cheaper and easier; it is not necessarily better, but if a manufacturer can make for less and sell for more, you can bet they'll tell you that it is.

The highly subjective "truth" is probably that they had to deal with not only wood warpage, but inconsistencies of steel structure that would lead to more accuracy-robbing behavior during heating and cooling. Locking a barrel down along its length would minimize the effects of this. By the post WWI era, the "big boys" would have had most of the steel production issues licked, but they had a system that worked and was almost traditional by then, so probably opted not to mess with it.

As Pietro said the bottom plate on a standard pre 64 is two piece. That 3rd screw makes the magazine short for long bullets. It was a selling point for the MRC 1999 action, that they eliminated the middle screw. My standard length 1999 action is chambered in 458 Lott.

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Originally Posted by murf205

The middle screw on a Tang safety Ruger 77 is there to help crack the trigger guard(pot metal) when you over tighten it! After I got the replacement and BARELY tightened it, the rifle started shooting a lot better.

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my short action mid-80s tang safety 7-08 shoots amazingly well provided that stupid screw is almost "shake hard so it'll fall out" loose

They put it there so people will wonder why they did it.

Actually, I put it in "shake hard so it'll fall out" loose, just to keep from loosing it. It should be held in with a short wood screw.

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Originally Posted by fatnhappy

my short action mid-80s tang safety 7-08 shoots amazingly well provided that stupid screw is almost "shake hard so it'll fall out" loose

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I wish my mid 80's 243 would have responded to that. I tried every trick I knew but finally gave up on the rifle and sold it. I would love to have that rifle back now. It would be a 358 Win with a Douglas barrel duplicate tapered to that stock. Such is life.

Doubt if it had anything to do with patent infringement on the Mauser design. By the time the Model 70 was designed, all the Mauser patents would have been long expired.



I don't remember patent duration, but I'm pretty sure it's way less than the almost 40 years from the introduction off the '98 to the arrival of the Model 70.


Copyrights can be readily renewed, patents on mechanical design take extraordinary circumstances to renew is my understanding.