Cutting a 307 Win rim into a 308 Win chamber

[briannmilewis]

Would a gunsmith need a chamber reamer to cut the 307 Win rim into a 308 Win chamber, or is it just a machining job?

[gunnut69]

The 307 is a rimmed round and as such it's rim is larger than a 308. Thus altering cases by cutting them down is not likely to work. But to answer your question a chambering reamer might be used to Cut a slotted chamber in a pilot(5C?) to allow it to grip the case firmly yet evenly for a maching operation.

[bcp]

It could be done either way.  But if the chamber has an extractor notch like most single shots, I would rather use a reamer.

A typical bolt action will have the head of the case out of the barrel far enough that a rim cut won't be needed, just a bolt face/extractor modification.

Bruce

[briannmilewis]

I think my language was a little sloppy, and I was thinking single shot, but didn't specify. However you got me the info I was looking for on both counts. Larry had already clued me up on the bolt face work he thought would be needed, to make the 307 work in a 308 rifle, so that was a +1 on that. Thanks.

[gunnut69]

Whoops!! I surely misread that one..  Glad you got the answer thanks..

[trotterlg]

Sorry I am so slow seeing this.  Been there and done that.  Larry

http://www.gboreloaded.com/forums/index.php/topic,168498.0.html

[briannmilewis]

Sorry I am so slow seeing this.  Been there and done that.  Larry

http://www.gboreloaded.com/forums/index.php/topic,168498.0.html

Larry: Speed of reply is by no means imfortant compared with the value of the knowledge you share. So the big eye opener is that you end up with a dual cartridge rifle - 307 Win and 308 Win? Not knowing the intricacies of the process, I had expected that cutting the rim would then exclude the 308. Wow, and better still, one extractor does both! Then if you cut an AI chamber you get both AIs! That is an outrageous deal for a small modification. Thanks for the insight.

[Sweetwater]

What am I missing here? The 307 is a 308 with a rim. I have a 356 which is a 358 with a rim. Doesn't make it a dual caliber rifle, just multiple brass sources. I even trimmed an 8x57 to length, necked up to 358 and loaded it with all the rest, and the rifle digested it, not knowing it wasn't a 356 case to start with...... it didn't care at all.

Regards,
Sweetwater

[briannmilewis]

What you get is a dual cartridge rifle, not a dual caliber rifle.

After the rim is cut to accommodate the 307 Win, it can fire both 307 and 308 loaded cartridges.

[Nessmuk#1]

I have a Marlin that shoots and feeds both just fine.  I've even necked up mil-surp brass and it worked fine.

[Sweetwater]

I have a Marlin that shoots and feeds both just fine.  I've even necked up mil-surp brass and it worked fine.

Will your Marlin feed factory 308W's, or do they have to have the bullets seated deeper? My Big Bore 94 Winchester will feed 358Wbrass, but not 358W factory ammo - it is too long to feed through the magazine.

Regards,
Sweetwater