300 win mag barrel used for 308?

[Craig 61]

I have a new 300 win mag barrel. Can i use this barrel on a 308 rifle since they are both 30 caliber?

[Swissfan]

The 308 is a short action and the 300 WM requires a long action. The base diameter of 308 is .473 and .532 on the 300 WM, so you would also need to change bolt heads.

[Craig 61]

I don't want to change calibers,just use the barrel

[wbm]

I have a new 300 win mag barrel. Can i use this barrel on a 308 rifle since they are both 30 caliber?

No.

[Dave Hoback]

As wbm said, NO. It’s not feasible to use that barrel & action together. Which cartridge are you attempting to use, 300WM or 308Win?

[charlie b]

If you want to change your .308 to .300WM then there are two problems as mentioned above. The action is too short and the bolt face is too small. The bolt face can be fixed, the action length cannot.

If you want to change the .300WM barrel to a .308 chamber then it might be possible. You'd have to have most of the chamber end of the barrel cut off and a new chamber reamed, as well as extend the threads. That might not be possible if the barrel starts to taper where you need to put the threads. That depends on the contour of the barrel. I suspect there won't be enough 'meat' there for that much of a cutoff. FWIW, unless you have a buddy who is a competent machinist/gunsmith, it will probably cost more for the machine work than it would be for a new barrel.

[Craig 61]

I have a new 300 win mag bull barrel from a project never completed. I thought i could replace the barrel on a used 308 rifle i'm getting.

[pdog06]

Nope.

The only variable would be if the 308 you’re getting is an older model that was built on a long action. Older as in like 15-20+ years old. Then the action would be big enough but you’d still need a bolt head and mag box swap.

[pdog06]

Wait a minute. You state you don’t want to change calibers and just use the 300wm barrel?

So by saying that you mean you want to know if you can shoot 308 rounds Thru the 300wm barrel since they’re both 30cal? That would be a huge NO!

[Craig 61]

Yes that was the question,I thought maybe because they are both 30 caliber,the difference would be in the receivers

[Blue Avenger]

Yes that was the question,I thought maybe because they are both 30 caliber,the difference would be in the receivers

Nothing in Rifles will do that! They have to be exact fits or they will expand and explode to fit the extra space. ( please! nobody confuse him with the fireform exceptions, that is a different game. )

[Dave Hoback]

OP… Which cartridge do you want to run? 300WM or 308Win. You still have not said. There are just so much info being thrown at you because you aren’t telling us what you want to do. So once again I’m asking, do want to run 300WM or 308Win​?

[Robinhood]

308 to 300 win mag: possible
300 wim mag to 308: Possible if you have a long barrel with a large shank. Otherwise nope.

308W on the left, and the 300 WM on the right

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