Home Forums Hunting & Shooting Gunsmithing M70 7 WSM chamber issues.

I bought a New Haven M70 fw chambered in 7 WSM at a gun show last year. Just started shooting it a couple weeks ago and found an accurate load with 150 Accubonds over IMR 7977.

But looking at the fired brass revealed an issue with the chamber. The brass has a slight bulge about 1/8" below the shoulder. The bulge creates a ring which is about 1/3 around the circumference of the case. This create a an issue when trying to load brass fired in the chamber unless the bulge is lined up perfectly in the chamber.

Has anyone seen an issue like this and what solutions are available, other than a new barrel.

Got a pic of a fired case? Could be a rolled chip when the chamber was being cut.

If it’s big enough that a sizing die doesn’t take care of it a new barrel or at least setting that one back and rechambering is probably in order.

If the same flaw existed on a 30/06, one could probably set the barrel back a couple of threads and rechamber. With the WSM cartridges though, there is not enough taper to the chamber wall so one would like have to set back much more to eliminate the flaw. You will probably have to rebarrel. GD

Thanks for your replies fellas.

Tried to upload a picture to the image gallery but no luck. The cases have a very slight ridge which is barely visible but is easily noticicable by running your fingernail over it. Also noticed after enlarging the picture was the area between the ridge and shoulder has scratches running around the circumference, but no scratches below it.

I'm only neck sizing this brass with a type S bushing die, but I could run brass through the body die, but I don't think this will resolve the issue. Like greydog mentioned, very little taper on the Whizzum case so barrel setback isn't a good option.

Seems I've heard of issues regarding the chambers on early Whizzum guns out of new haven. Gun has a beautiful wood and may be a pretty good shooter. Already dumped a few hundred in it for bedding, 1 pc bottom metal, base holes drilled to 8-40. I'll let my gunsmith look at it but it's looking like a new barrel is in order.

Seems like last couple of guns I've bought ha e been money pits.

I would say run a case through the FL or body die and see if it sizes the ridge and chambers easily. If so then just FL every time if it proves to be a shooter.
If not a rebarrel is your best bet.

A few years back I had bought a brand new Winchester M70 a New Haven rifle and the first time I fired it I set a couple brass pieces down on the bench and I noticed they rolled funny. After further inspection

and a visit with a local barrel maker and life long gunsmith, we concluded the chamber was quite out of round. Ended up re-barreling the rifle. It was a 300WSM. Probably your only option.

I'm believing that a new barrel is in my future. I've heard some of the New Haven Whizzums had chambers out of round.

There is a history to this and it is not uncommon. I think that there might have been a recall. A barrel setback or new barrel is the fix. There is not much taper to the WSM case so a barrel setback might not be possible or would leave a big gap in the stock that could easily be fixed. To me it would be an ideal excuse to get a faster twist barrel if you had any curiosity in how the 180 & 195s might perform.

Not sure if there is any warranty but might be worth a call to FN/Winchester.

Eureka. Finally remembered how to upload a picture.

You can see the slight ridge with circumferential scratches below the shoulder.

Not looking to shoot heavies in this gun. 150 - 160 gr bullets will be just right for an "all around' Bama deer gun from 30-500 yards. The 150 gr Accubonds should do this nicely at 3100 FPS.

Google Winchester WSM chamber issues. I recall they were round when chambered when barrels were installed they went out of round.

The New Haven rifles had a 1"x16tpi interrupted thread. It was interrupted because the locking lug raceways were cut all the way through the receiver threads. The barrel threads were often a little bit loose and, when the barrel was tightened into the receiver, it would become oval. This was, of course, most apparent on the WSM chambers because the chamber diameter was so large. When Winchester started making the actions for the wssm's they made these receivers with a 1 1/16"x 28 tpi thread and tightened up the tolerances. I will not re-barrel a WSM without opening the thread up to 1 1/16x16 tpi.
The OP's rifle appears to have a flaw which is mostly cosmetic providing cases are FL sized. The chamber could be improved but not totally fixed by honing but, in my opinion, it should be re-barreled. GD