walking barrel

[moooose102]

i have a remington 700, 300 win mag that the barrel walks as it heats up (the point of impact goes up). so reading and talking to several people, i decided to remove the "pressure point" in the stock to free float the barrel. i went and shot it yesterday, but it really made little difference. it may not walk as much, but it still does it. to the point of having to stop after 3 shots to let the barrel cool so i can hit on target (bullseye) again. it is a mid eighties vintage 700 bdl if that makes any difference. it has the standard barrel contour also. so what will stop this? i thought about full length glass bedding, but if the barrel is raising up free floated, why would it not raise up off from a glass bedded stock? am i doomed into replacing the barrel? do the open sights have anything to do with it?

 

[alsaqr]

It is not unusual for a gun, especially a magnum caliber gun, to change point of impact as the barrel heats. In hunting it is unusual to fire more than three rounds in quick succession at a game animal.

Just removing the barrel bump in the stock does not fully float the barrel. One has to relieve the barrel channel until a business card can be inserted between the barrel and stock. Have floated the barrels and glass bedded the actions of a lot of Remington 700 guns. Usually accuracy is improved-sometimes it is not. Fully floating the barrel and glass bedding the action may help accuracy as the barrel heats up but at some point the barrel will get so hot that accuracy goes south.

My advice is to not let the barrel get so hot during range firing. Take another gun with you and fire it while your .300 cools. It has nothing to do with your open sights.

 

[moooose102]

I did check the stock - barrel clearance after i re installed and tightened the screws. A dollar bill went between the stock and barrel up to the point where the barrel gets big. So, being a beginner at this, i would think that is free floated. I wonder if some kind of something fashioned as a temporaray barrel band would help while i was target practicing. I do take at least 3 other guns with me when i go. And i still end up waiting. Ibecause all of them do pretty much the same thing. Except the 22's. But shooting round after round for no other purpose other than wasting time just gets boring. I know it is good trigger finger practice, but i shoot enough to stay on top of that. I have often wondered about pouring water across the barrel to cool them. If it would warp them or something. They are not so hot i can not hold onto them. If they were, i would want them to cool. But really, the 3 hunting rifles i have, all need to cool to ambient temp before they will shoot correctly again. Maybe that is part of the draw to a custom barrel. I dont know, i have never owned one. If i had the money to blow, i would at least call and find out. But i see no sense in jerking these folks around for nothing. They have paying customers to take care of.

 

[Jon_Snow]

When you slipped the dollar under the barrel, did you do it while the barrel was hot? It may be free-floated at room temp, but not after you've shot those three rounds. That's why the business card at room temp is a better goal.

 

[moooose102]

No, i did not. Just at room temp when i finshed the job. I will have to take it out, and get it hot and see if the clearance has gone away.

 

[BADUNAME27]

Your zero shifts when your lightweight sporter barrel chambered in a big magnum cartridge heats up.

There are two offerings to resolve your dilemma.

1. Don't shoot so fast.
2. Get a heavier barrel.

Just as it's outside the design parameters for an M-4 to be used as a defensive crew served machine gun it's the same thing with your big boomer fitted with a spaghetti barrel.

Slow down and it'll be fine. It's a hunting gun intended for one or two shots, not sustained rates of fire.

Good luck.

C

 

[NCsmitty]

+1 for LongRifles, Inc..

You are igniting at least 75gr of powder and it produces a lot of heat in that hunting contoured barrel.
If you want to shoot strings of target rounds, you need a heavier barrel.
The important thing is if it hits POA with the first shot in it's present form.


NCsmitty

 

[1911Tuner]

Good posts and good explanations on the phenomenon.

If I may...

Barrels go throuh several machining steps from a blank length of steel to a finished barrel.
As each step is completed...the prospective barrel usually needs to be straightened before moving on to the next process due to the removal of material relieving stresses in the steel. After the barrel is rifled...it's again straightened before final assembly...and then it's checked for straightness after being torqued into the receiver.

Then, when it heats up from firing...it warps again. Because steel has a "memory"when it cools off, it goes back to its post-straightened shape.