I picked up an old FN Mauser chambered in 300Sav. Will a 308Win reamer clean up the chamber? The diagrams look to me like the 308 may be slightly less diameter than the Sav near the shoulder, in other words I could end up with a slight bulge in my cases.

The .308 Winchester reamer should totally clean up the 300 Savage chamber.....or to the point that you woon't notice a thing.
Personally I'd not hesitate to do the surgery.

fla3006: My understanding is that FN's in 300 Savage are pretty uncommon and thus quite collectible. That cartridge also happens to be one of my favorite deer cartridges and really doesn't give up all that much to the 308 when looked at objectively. I wouldn't rush to make that change.

There's a chance that the .308 reamer might not fully cut out the old .300 chamber's shoulder, depending on the dimensions of the original chamber. The barrel might need to be set back by a thread or so.

But as stocker says, DON'T DO IT! The .300 Savage is what the .308 should have been. I think that perhaps military designers were simply afraid that the sharp shoulders on the Savage might not feed smoothly or that the short neck might not have a firm grip on the bullet. Both fears are unfounded. In similar guns and at similar pressures, there is essentially no ballistic difference in the two rounds. Besides, your orignial FN .300 Savage will ALWAYS be worth considerably more than a rechambered gun.

Thanks everyone.
The rifle is not a fine factory FN Deluxe Sporter but is a semi-custom made on an FN Deluxe action that's had a fair amount of use. It has not been D&T but has Lyman 48 and Christy banded ramp sights, marked C.R. Peterson & Son on barrel & recoil pad.

I love the .308win I own more rifles chambered for this cartridge than any other. I also must say that the .300savage is a neat little round as well.

Forrest,
would like to see that one before it gets rechambered... neat caliber! .. and a 308 will totally clean the chamber.

jeffe