I have a Remington 700 purchased used. The left bolt lug is worn to show bearing on about 60% of its surface. The right lug shows little wear and hardly contacts at all. How much is accuracy affected by this?

This is just a question of curiosity as it is a donor that will be off to the gunsmith to have the action trued and rebarrelled soon. TIA, Ed

Well, it is not in the best intrest of ulitmate accuracy. Definitely need more even bearing to get the most out of a rifle.

I know that some folks really get up tight about opening Mausers for .375H&H cartridges, saying it is too weak. Yet there are countless rifles, possibly sitting in their own gun safes, shooting with no problem with only one lug bearing at all. An opened up Mauser looks like the door to a bank vault in comparison.

I don't know about the accuracy thing frankly, but would be worried some about possible breech or bolt failures? If one lug isn't contacting at all, I wouldn't think that too cool myself; all the loads going one place.
I have read in the past about some "new" rifles sometimes doing similar until they seat(?)/deform after a bit, especially with more/many lugs, but even then it is more of a poorer quality issue I think.
Then again, what the heck do I know for sure...ha ha. In the military stuff I used to manufacture, this would be a "no no" condition however....
Good luck and take care.

I would venture to say that almost all of them have the top lug not touching when the rifle is cocked. The cocking piece pushes the back of the bolt up and that forces the top lug away from the receiver. That's why I don't lap lugs any longer. Cock the bolt in your rifle and watch it. On a BR rifle where the bolt is a .001 clearence to the body, that is a different story.
Butch

Good call butch, but he said the right lug shows little wear and that would be the bottom one. But how was he looking at the bolt?
I have had good luck lapping with very fine paste with all the parts out of the bolt or the trigger and sear removed. Just barely enough to get better contact. Can't get carried away.

Big Ed

You didn't say what cartridge but I wouldn't worry too much about accuracy in a factory M700. If it hasn't been shot a lot it could eventually even itself out.

Be careful if you intend to lap the lugs. It could change the headspace if a lot has to be taken off the one lug that does bear. And you have to know what you're doing otherwise you might just make the situation worse.

Ray

quote:

Originally posted by bfrshooter:
Good call butch, but he said the right lug shows little wear and that would be the bottom one.

Unless he's left handed.

M700 receivers tend to be bent/warped from heat treating which adds to the single locking lug bearing issue. The 40X receivers were heat treated first avoiding some of this. The steel used in a M700 is so much stronger than a Mauser that I would feel safer with a one lugged Remington than than a stretched 375 M98. Remember the Remington ius trrhough hardened steel. The Mauser is only hard on the skin.

Thanks to all. Don't worry, I'm not lapping the lugs though that will be done as part of my gunsmith's rebarrel so headspace also isn't an issue I will deal with. Yep, it is the right lug that shows no wear and, yes, that's the bottom lug. The rifle is/was a 7mm Rem Mag but will be a .257 Roy in its new life.

My curiosity is related to how much uneven lug bearing affects accuracy. Since it was a donor, it didn't and won't be shot before the rebarrel since I still have a few "donors" that shoot too well to tear apart. Ed

I have seen 40x's and Remington Custom Shop 700's that were worse than the average M700 you could buy at WalMart.

quote:

Originally posted by BigEd:
My curiosity is related to how much uneven lug bearing affects accuracy.

Anything that allows the axis of the bullet to slip out of alignment with the axis of the bore is detrimental to accuracy. Out of whack lugs certainly do, an off center throat will. Too much slop between the chamber walls and the cartridge case does it. The more you can do to reduce these errors the better. If your gunsmith trues your action at the time he rebarrels it, that will solve the lug issue.

quote:

Originally posted by Marc_Stokeld:
I have seen 40x's and Remington Custom Shop 700's that were worse than the average M700 you could buy at WalMart.

Receivers are like barrels. Some just happen to turn out straight. Many don't.

quote:

Originally posted by Marc_Stokeld:
I have seen 40x's and Remington Custom Shop 700's that were worse than the average M700 you could buy at WalMart.

The worst one I saw ran out almost .030" on the threads versus the Bolt raceway.