Shoulder angle rounded

Ive just had a call from a guy who got a new barrel installed. Its a 7mm-08. His problem is, he's finding that his brass is very rounded at the shoulder angle after firing. I told him to bring it up so I can take a look. My take on it before I even look is that his smith must have over polished it and over done it a little at the shoulder. He said he used a brand new reamer so thats all I can think it could be. What do you guys think.

Were the shoulders sharp on the brass before firing?Butch

It was new brass so Id have to say yes.

It would be very hard and take a very long time to polish a shoulder in a chamber to make it round. I would check the reamer.Butch

I would also say define rounded? You wouldn't want a real sharp angle.

Also is he firing reloads? Like light starting loads?

Define rounded, well I mean really rounded and comparing new brass to the fired brass, it looks to have gained about 3.5mm in length from the bottom of the shell to the first angle, then a massive rounding of the shoulder, enough to 3 nice cracks. Im sorry, I meant to say its a .300 7mm wsm not a 7mm-08 as previously posted. I think its got to be a wrong reamer, possibly a weatherby magnum or something like that. Ive contacted the reamer maker but its shotshow week so Im not expecting anything for a few days.

Is it a .300 or a 7mm? Goatwhiskers

Goatwhiskers said:

Is it a .300 or a 7mm? Goatwhiskers

Click to expand...

i am guessing a 7-300wsm, a 300 wsm case necked down to 7mm.





it sure sounds like there is something seriously wrong with the chamber or the wrong cartridge is being used in it. just thinking out loud here but i don't know what exactly would happen if a 7-300wsm case was fired in a 7wsm chamber, or if you cold even get the bolt closed on one. i don't have the dimensions in front of me now but i think the 7wsm's shoulder is a bit forward compared to the 7-300wsm. if the shoulder if very far forward, i don't know if it would perfectly fireform to the chamber or round and split, like it sounds like what happened.

Im starting to smell what happened here now. The clients rifle is a 7-300, they ordered 7mm wsm and this is what I think has gone wrong. I still could do with input here. Would a 7-300 shell fit in a 7mm wsm chamber.

Might be a good idea to compare the reamer and a cartridge. Sounds like the wrong reamer was sent.

Ill have it my shop tomorrow, its never that easy to do a good comparison with a round and a reamer but Im really looking forward to taking a look at it to see what the story is.

i'm curious if you figured this one out yet.

It's either wrong cartiguide/ reamer combo or a serious case of loading the reamer up so bad that the shoulder of reamer was messed up.
I am curious myself , let us know.
CEW

Sorry guys, I meant to get back to you sooner on this one. Its the reamer alright. This guy had a huge communication issue between himself, his client and the reamer manufacturer. The client wanted a 7-300wsm chamber but he told the smith it was a 7mmwsm and never taught to mention the .300 part of th equasion. the smith asked him for a few brass samples to send to the reamer maker and spoke to him over the phone about the neck size etc and not knowing anything about .300 end of things sent the brass away. The reamer maker got the brass and still not having heard nothing about the .300 part proceeded to measure the neck size and over looked the print on the base of the brass. the reamer came back, the smith chambered the barrel and then went to test fire the rifle. Oh oh, something dont look good here he taught. He brought the fired shells up to me to see what I taught. After a lot of headscratching I told him to contact the reamer maker which he did and sent back the reamer and the dodgy brass. That night it struck me, nobody ever thought to mention to the the other that this was a 7-300wsm and not a 7mm wsm. So what happened was he was firing a 7-300 round through a 7mm wsm chamber. Lucky no was hurt. This was a very expensive lesson and one which could have been easily avoided if the shooter was using his head in the first place. Now the smith has it all to do to try and correct this. And the Moral of the story ?

good to know it was figured out. i'm not totally sold on the benefits of a 7-300wsm over a standard 7wsm. i don't think the longer neck is worth the loss in velocity, at least for what i would be doing with it.

Glad you figured it out. BTW the first step would've been to take a chamber casting to identify the problem.

A chamber casting would have been a good idea but as usual a friend borrowed my cerosafe and wasnt about when I needed it. Never lend anything again.

a solution to lending stuff

"Never lend anything again."

Al Mirdoch said to get a full deposit on the value of the goods loaned.

Then stuff was either returned quickly or replaced.

We were discussing old shooting books at that time.

It works!!

Glenn