Home Forums Hunting & Shooting Gunsmithing Win model 70 problem

A guy showed up at the shop yesterday with a model 70 classic in 300 WSM saying he was having inconsistent problem with chambering full length sized rounds. I went through it, checked the settings on his sizing die, bolt clearance in the action, extractor clearance, headspace check, etc, all checked out OK. Could not come up with an answer so decided to pull the barrel. When I did, I put in my reamer and turned it by hand. I could feel it cut a small amount, pulled out the reamer and guess what, two shiny spots in the chamber near the back on opposite sides. THE CHAMBER WAS OUT OF ROUND!

The rifle belonged to his brother in law and he only shot factory ammo and had shot it for years that way. The deal with not fitting, if he took a full length cartridge and tried it in the chamber, unless it was oriented the same as when it was fired, it would not fit. How did Winchester cut a chamber out of round???

Jim

Very common problem with late NH WSM guns. I've got a 7mm WSM and a 300 WSM, both very early rifles without the problem.

I've also checked end of production WSM rifles in the same calibers with egg shaped chambers.The 7mm would chamber one type of commercial ammo fine, another type with some force required on the bolt, and another brand of ammo would not chamber under any circumstances. Best bet is a rebarrel.

I'm certainly not a gunsmith or machinist, but have done a little work with reamers...how do you get a reamer to cut an out of round hole?

I read on the Internet (so it must be true) that Winchester switched from the 1"x16 thread to the 1-1/16"x28(?) because the receiver threads that were interrupted by the raceways was causing this out-of-round problem on the WSM chambers when the barrels were tightened up

Common problem with the WSM's of that vintage (assuming late USRAC production). They were torqued too tight, which egg shaped the chamber... Do a little research, this has been discussed before..

I have also encountered this. I believe the culprit was over tightening those barrels. I had a guy bring a new model Ruger Blackhawk into the shop that just would not shoot to please him.
It was a 45 Colt. When I tried to pass the range rod through from the muzzle, it would not go past the forcing cone. Pulled the barrel and installed another everything was fine. Again, over tightening was the culprit.

I know that YOU know the answer to that as easily as I..

But part of the problem was alleged (note: alleged) over-tightening of the barrel to the receiver.. Yeah, it's been written about. So has global warming.. Both taken with truckloads of salt.. IMHO that would take one helluva lot of torque to get to that point..

My question is: why was this phenomenon supposedly only with WSM rounds and not other magnums etc?? Do they not tighten the barrel (roughly) the same on each rifle? Wouldn't THAT cause egg-shapes on others? Why only WSMs?

One way to find out if your barrel could be an over-tightening problem is noting exactly where those two spots are. Do they coincide with the center of the uninterrupted thread section of the receiver? Or not?

FWIW I've run into egg-shaped chambers on Rem 700s too - and it had nothing to do with WSMs or interrupted threads..

YMMV

I had not heard of this egg shaping. Perhaps the rumor / fact/ whatever, has to do with the larger diameter of the WSM, WSSM cases leaving less meat? FWIW I think the Win 70 Fwt defeated that argument in 1952!

I have seen / heard of a large number of new rifles in the past 6 or 7 years needing major chamber work to include rebarreling across the mass produced manufacturers, i.e. Rem, Win, Moss, and Savage. QC took a hit to hurried production for profit....or not??

Good refresher. I'm adding a quick spin with a snap gauge when looking into chamber issues.

Figuring about .020/side extra. But there's still the entire shoulder of the barrel in contact with the receiver to figure into this.. It would require an actual stretching to get there.. I'm just not buyin' it..

And I've had a few NH WSMs in the shop w/o any chamber problems. Wouldn't they have barrels attached just as tightly? I've had an easier time getting those off than a few others with standard-sized chambers..

IMHO it's a crap-shoot.. And that goes for all of 'em..

During the hammer forging process some manufactures have the chamber on the barrel mandrel as well. I would suspect that was the cause more than anything else. Just sayin.

Good point..