how careful does one need to be to not permanently bend a M70 long action receiver by putting excessive pressure on one or more of the guard screws?

As with any bolt action. VERY careful; they are super easy to bend.
Your bedding has to be right to prevent bending; if you are worried about it, then the bedding is the answer.
Easiest is Mauser tangs, but they all will bend. Except maybe the big tube types like Bench rest shooters use. Several makes of them.

Absolutely right! I install 10-15 triggers a day in Remington M700's and can tell you that screw torque can bend the action enough to vary the out of stock trigger pull by up to 1.5 lbs in any direction. I did one today and it gave a factory acceptable 4 lb 2 oz outside the stock, but when screwed in it went to 3 lb 1 oz. Much of this problem is due to fore/aft bedding issues. The "spaghetti" Walmart stocks on ADL's are the worst. The pillar bedded premium stocks hardly vary. Any bending would likely be temporary as it is just a slight amount. But any flex in the action can/will affect the sear engagement.

quote:

Originally posted by dpcd:
As with any bolt action. VERY careful; they are super easy to bend.
Your bedding has to be right to prevent bending; if you are worried about it, then the bedding is the answer.
Easiest is Mauser tangs, but they all will bend. Except maybe the big tube types like Bench rest shooters use. Several makes of them.

Permanently bend it?

The alloy receivers take a lot of distortion to permanently bend.

They don't take much to flex, though, in poor bedding as others have mentioned. Fine pitch screws are remarkably efficient machines and put a lot of force on the action at very low screw torque values.

That said, they aren't always that straight from the factory.

Jeremy

yes, permanently bending it. I realize they are not difficult to flex, but am wondering about a permanent bend as a result of the combination of bedding that is not correct and snugging up guard screws a bit too tight. thanks for the replies.

No, you aren't going to permanently bend it. Receivers are made to flex. But your accuracy will not be good if you bend it any at all, temporarily.
True, they aren't necessarily straight as is, but you don't want to change that. That is why some target rifles bed the barrel and leave the receiver floating.

quote:

Originally posted by devere:
yes, permanently bending it. I realize they are not difficult to flex, but am wondering about a permanent bend as a result of the combination of bedding that is not correct and snugging up guard screws a bit too tight. thanks for the replies.

You would have to exceed the yield point of the steel, in this case 4140 probably around 85,000 psi.
Doubtful you could ever get enough torque on a 1/4" slotted screw to do that!

Doug, you are going to be closer to 130,000psi yield for quench and temper 4140. Most receivers are tempered to something around 30 Rc.

To your point though, it might flex, but the receiver is not likely to be the weak link for something to bend.

Jeremy