weatherby mk v

[fast427ci]

My friend needs a Smith to look at his weatherby mark v, it is chambered in 270 wby and somehow got a 7mm wby in the chamber and touched it off, you can almost read 7mm on the bolt face!!! Any help would be gladly appreciated!!!!

[JeremyD]

http://www.firearmfinishinginc.com/

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[scrappy]

That is very interesting indeed. I just looked at the case specs of the two and I would have thought that the 7mm being .009" larger dia at the neck would certainly have prevented it chambering in the 270 chamber. I had also thought that the 7mm case was slightly longer, but my Speer manual shows the length to the front of the shoulder as being 2.218" for the 7mm WM and 2.221" for the 270 WM. Meaning that if the .009" larger diameter neck of the 7mm would somehow fit then nothing else would prevent this from happening. It still surprises me that this could happen as that .009" difference in neck diameter is huge and it should not have fit.
I am inclined to believe that the Mk-5 action would have been up to the challenge, but be certain to have it checked out by a competent gunsmith. They will likely need to magnaflux the action to check for microscopic stress cracks. Years ago I read of a Rem 700 in .270 Win that suffered a similar incident. The shooter accidentally chambered a 308 Win round and fired it. The 308" dia bullet filled out the chamber right about where the neck of the 270 case should have been which allowed it to headspace enough to be fired. The pressures that were generated by forcing a .308" dia bullet down a .277" dia hole must have been stratospheric, but after a complete exam the 700 action was pronounced undamaged.

[fast427ci]

thanks I'll check into them, and see what they say! I know scrappy I wouldn't think it would fit either, but I wasn't there I don't know if he beat the bolt down with a hammer or it simply had just enough resistance to not worry him! I just didn't know if he needed a Smith that specialized in weatherby rifles or not!

[scrappy]

Any chance he was using reloaded ammo? if so the 7mm case could have been run through a 270 sizing die and there would'nt have been a problem. Did he say anything about how he got the bolt open after the shot?

[fast427ci]

no he didn't in actuality its my friends dads rifle and hes the one that shot it and it scared him after it happened and put it away thinking it was ruined, so many years after it happened we are here! so I really only know the bare facts! I don't know if he was a reloader or had another wby in 7mm and just grabbed the wrong box. but my thinking is, if it was only fired one time with the wrong cartridge it might be ok, but then again I'm not a Smith either!

[roger]

http://www.firearmfinishinginc.com/

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[high country]

that is a tough one to diagnose damage on. its going to need the headspace checked first, and if its good.....i wouldn't give it grace without pulling the barrel and looking the action and bolt lugs over. they really made a pita action with all those lugs.

[ron]

http://www.firearmfinishinginc.com/

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+1

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Agree 100%. also agree with what High country said about the degree of difficulty of determining wear or damage on multiple lugs instead of just two.

I fired an 8mm mauser round in a 30-06 once but luckily it was Remington commercial 180 grain round-nose and they're loaded down to the same 38,000 PSI pressure levels as the 30-30 plus the longer chamber of the 30-06 had a lot of "freebore". The rifle was a 1917 remington enfield and in WWI it was often rumored that they were able to fire the German's ammo in these guns.

I had two boxes of ammo, Remington 30-06 180 grain RN and 8mm mauser 180 grain RN and at a glance both boxes looked the same and even the round nose ammo looked similar. I discovered my mistake when the fired 8mm case was ejected and the case looked like the length of the neck was only an eighth inch long after being fire-formed in the 30-06 chamber.

But in this situation we're dealing with much higher pressure levels. So depending on what the gunsmiths say, it would probably be best to only use handloads in this gun and load a little below max so that the velocities you get will still be better than a 270 Winchester but not quite as high as standard loads for the 270 weatherby, but more like what you get with the 270 WSM.

Any of the weatherby rounds are probably best for handloaders anyway because of the cost of factory ammo.

[fast427ci]

I would like to thank everybody on their input, my friend is going to take the wby to firearm finishing next week to see if it will recover or not, will update when he comes up with an answer

[high country]

take a fired case from pre oopsie and the one that is in question with it. if the headspace moved visibly between the two, you can stop right there.