While slugging the throat of a G4xxxx series Stainless Classic M70 '06, I learned that the leade was not cut evenly. While the rifle has not yet been wrung out for accuracy potential, it hasn't shot such that it raised any flags for plain factory issue.

The overall dimensions are at the maximum of the chamber drawings in the back of NRA's "Handloading" book with a throat of .3125" at the neck, tapering approximately .001" per .050" to a groove diameter of .3095" at .100" forward of the first leade.


I will continue to diddle with it for fun but at some point, especially if it never does shoot particularly well, will want to do something.

Question is: being that the throat is already on the fat side, is there any reason to try to rethroat the barrel? Would a new barrel be a better/simpler solution? How about a rebore to .35Whelen? (although I've heard the stainless steel Winchester used in thier barrels can be a bugger to rework)

I'd set the barrel back one or two threads and re-chamber.

Dave Manson

As Mr Manson has pointed out setting the barrel back would be the best and simplest way to deal with a chamber at max and your leade issue.

Having said that, there is a pretty good chance your gun will shoot just fine the way it is, I'd try larger size bullets in the 180-200 grain range and it may shoot just fine for you, especially for a hunting rifle.

Thanks for the advice, I'll go with a barrel setback when I get the time and money.

The slugging was to fit a cast bullet to the rifle but I'll wait on that project until after cleaning up the chamber.

The rifle has shot some nice groups as is but you know how we all want to shoot bugholes every time...

One of my M700s has a hideously lopsided throat, one of the ZGs (270)has a DIY dremel job on the throat to accomodate 160s to mag length, my 6.5 doesn't have a throat and my 30-06 has about 6" of rifling... As far as I can see the accuracy of a rifle is determined by the quality and straightness of the end of the barrel and the beginning has little to do with it.

If the throat is eccentric to the bore, the neck and the rest of the chamber probably is as well. This makes it very difficult to correct the deficiency by setting the barrel back. The barrel would have to set back by at least the length of the neck. The barrel would have to be set up so that the new throat area runs true then the neck portion bored out so it no longer influences reamer alignment. Still, the reamer will be influenced by the body portion of the chamber and even a tight fitting pilot can't correct for this 100%.
If one is rechambering to a larger cartridge, it is possible to bore enough of the body to correct misalignment but when you are staying with the same cartridge, it's tough to fix.
The upshot is this; correcting a misaligned chamber is more difficult than doing it right in the first place. The effort required to produce a chamber that may still be flawed is great enough the effort is better spent on re-barreling.
Bottom line? Shoot it as it is as long as accuracy is acceptable to you. When you are ready, re-barrel and have the new chamber cut with a throat which will be a better configuration for cast bullets, if that's what you want to shoot. Regards, Bill.

quote:

Originally posted by Bill Leeper:
Bottom line? Shoot it as it is as long as accuracy is acceptable to you. When you are ready, re-barrel and have the new chamber cut with a throat which will be a better configuration for cast bullets, if that's what you want to shoot. Regards, Bill.

Thanks for the further advice. Looks like I'm out of a job until this spring so I'll shoot it (after replacing that stupid bubblegum bedding compound that comes out with the action when you pull it from the stock ) and if the accuracy isn't there, it's off to the gundoctor. If he finds that the chamber is too far out to work with, I'll have a new barrel installed.