If it has the early style bolt you will need to have a gunsmith custom fit a barrel. If it's the newer style (1966 and up), any pre-fit or modern factory take-off barrel will screw right on.

Early style bolt is on top, new style on bottom.



Early style bolt is on the left, new style on the right.


The other option (if you have the early style) is to replace the entire bolt assembly with the newer style which will allow you to use the newer style barrels. Probably looking at $160-180 for a complete bolt assembly though.

And since I know someone will ask, no you can't simply swap on a new-style bolt head. If you look at the first photo above you'll see that the cross pin that holds the bolt head in place is is vertical on one and horizontal on the other (in relation to the bolt lugs)