Pre 64 M70 load questions

[SDHNTR]

Finally found the nice, un modified, shooter grade pre 64 M70 I’ve been looking for. How careful do I need to be with ammo pressure? I’m not worried about action or barrel so much, I’m worried about stressing or cracking the un bedded wood stock. And no I’m not going to bed it either. I want it to stay original.

 

[davidsapp]

What cartridge is it chambered for? I couldn’t imagine that it would matter unless you’re talking about a magnum like a 338 or 375.

 

[SDHNTR]

.270 win

 

[Wapiti1]

Load it however you want. They actually hand fit the recoil lug to the stock. No other way to do it back then. They didn't have a sloppy mass produced fit. If the wood is sound, it will be just fine.

The only caveat that I'll mention is oil. Make sure the stock isn't soaked in oil, and soft. If the wood is black, or very dark, push on it with a screwdriver handle and see if it seems soft. The finishes back then didn't seal oil out and over time it soaks in softening the wood. If it is normal color and hard, then no worries, shoot away.

It's not like 1957 .270 Win ammo was less powerful than todays ammo. They loaded them to the max with what was available at the time just like we do today. I've got some really old reloading manuals that are downright frightening with some of their loads.

Jeremy

 

[SDHNTR]

That’s good info. Thanks.

Was also thinking of either finding an aftermarket synthetic stock of some sort to shoot it in, or buy an old factory stock that had been modified (usually recoil pads) off eBay or something, bed it and shoot it. Keep the original in the safe.

 

[S-3 ranch]

That gun will handle 55-56.5 grain of 4831 behind a 130 nosler partitions or accubond.
easy

 

[ResearchinStuff]

I have some 1960's era reloading manuals that typically show starting loads at or above the max loads in the current manuals for the same cartridges. For a long time they were all I had, and I used them safely for 25/06 and 300 win mag loads growing up. I've heard that over time manual makers reduce the max for a given cartridge because of some assumptions about gun age/abuse/weakening, but that could be hearsay.

Anyhow, when the recoil lug is in good contact with the stock the stock itself sees very little of the chamber pressure because the bolt face is relatively small compared to the rest of the system, and the recoil lug is relatively large. Any forces on the stock are via the recoil lug, which is only reacting to pressure felt on the bolt face via the base of the case because of the axial pressure from the powder burn/expansion. The radial pressure is carried by the brass, chamber and barrel as the bullet travels. Since the area of the bore and bolt face are much smaller than the area of the chamber walls and barrel tube and the pressure (force per area) is felt in all directions equally, there is much less force in the axial direction (i.e. into the bolt lugs, recoil lug, stock and your sholder) than there are radially into the chamber and barrel.

In other words: the concern with an overpressure load really aren't the stock failing, it's one of the metallic pieces in the brass/primer/chamber/barrel/bolt face/bolt lug area failing. Of courese, if you blow your gun up the stock will probably also be damaged because high velocity metal is not kind to wood.

one last point: If the recoil lug is not making good contact with the stock, and that force is now being supplied by the action screws, or worse yet a single action screw, firing pretty much any round is fairly likely to initiate cracking in the stock at the rear of that action screw because the rear of the action screw is a relatively small area, and could be transmitting a lot of force, acting like a dull wedge. So, make sure the recoil lug is making good contact and enjoy your new toy.

 

[handwerk]

I load for 3 different pre 64 M70 .270 FWTs and have had no issues being at about max loads of 4831 or RL 22

 

[SDHNTR]

I have some 1960's era reloading manuals that typically show starting loads at or above the max loads in the current manuals for the same cartridges. For a long time they were all I had, and I used them safely for 25/06 and 300 win mag loads growing up. I've heard that over time manual makers reduce the max for a given cartridge because of some assumptions about gun age/abuse/weakening, but that could be hearsay.

Anyhow, when the recoil lug is in good contact with the stock the stock itself sees very little of the chamber pressure because the bolt face is relatively small compared to the rest of the system, and the recoil lug is relatively large. Any forces on the stock are via the recoil lug, which is only reacting to pressure felt on the bolt face via the base of the case because of the axial pressure from the powder burn/expansion. The radial pressure is carried by the brass, chamber and barrel as the bullet travels. Since the area of the bore and bolt face are much smaller than the area of the chamber walls and barrel tube and the pressure (force per area) is felt in all directions equally, there is much less force in the axial direction (i.e. into the bolt lugs, recoil lug, stock and your sholder) than there are radially into the chamber and barrel.

In other words: the concern with an overpressure load really aren't the stock failing, it's one of the metallic pieces in the brass/primer/chamber/barrel/bolt face/bolt lug area failing. Of courese, if you blow your gun up the stock will probably also be damaged because high velocity metal is not kind to wood.

one last point: If the recoil lug is not making good contact with the stock, and that force is now being supplied by the action screws, or worse yet a single action screw, firing pretty much any round is fairly likely to initiate cracking in the stock at the rear of that action screw because the rear of the action screw is a relatively small area, and could be transmitting a lot of force, acting like a dull wedge. So, make sure the recoil lug is making good contact and enjoy your new toy.

Good info, but I realize all that, which is why I said I wasn’t so concerned about chamber pressure. I will check for good recoil lug contact.

 

[ResearchinStuff]

Good info, but I realize all that, which is why I said I wasn’t so concerned about chamber pressure. I will check for good recoil lug contact.

I must be completely misreading your op then, I thought your concern was excessive chamber pressure cracking the stock.

 

[SDHNTR]

I must be completely misreading your op then, I thought your concern was excessive chamber pressure cracking the stock.

Sorry I can see that the way the title was written.

 

[hodgeman]

As mentioned... when you read some of the old load manuals and some of the stuff O'Connor wrote, I'd load it up and rock on.

Be aware, some of the powders changed over time meaning that 1960 4831 and 2022 4831 aren't exactly the same thing. As long as you're staying in the current products and manuals- you'll be just fine. Also, pressure testing and chrorongraph technology has come a long way since then so I'd take old data from those sources with a grain of salt too.

 

[MJB]

I have the same gun started shooting it for Tejon with hot tsx loads. No mods on mine, now it's time for a new barrel due to the blue wearing off.
It's been my California copper BG gun used every year.

Don't go synthetic get a newer wood stock and enjoy it in the woods.

 

[Wrench]

Pay attention to the stock at the rear of the action. If the action bears tight against anything to the rear, your odd go up quickly. Anything that touches the stock in a plane parallel to the bore is a place for cracks to start. The wrist is typically from side loads and impacts.

 

[SDHNTR]

I'm going to shelf my nice original stock to preserve it and try to find a beater pre-64 featherweight stock that's had a recoil pad added or refinished or something that kills value, glass bed that one, and use it for my shooter. At least that's my plan... If I could only find one at a reasonable price? Anyone got one laying around?

 

[kevin11mee]

I have a pre-64 M70 in .270 and I don't think you need to worry about the stock with handholds. The rifle was my dad's hunting rifle for at least 40 years and I know he pushed 130's as fast as he could from it. Just treat it as a normal rifle and look for signs of pressure as you move up. Wood is strong and an excellent material for a stock, it won't crack.