I have an Enfield Mark 4 in 303 British (of course) and need a new barrel for it.

anyone have any suggestion on where to get one?

Have you tried Numrich, Sarco, and the Shotgun news ads?

I would start there and if all those fail try doing a search for Enfield collectors groups, they can sometimes be allot of help in finding parts. I have two 1898 US Krags and it took me going to a Krag collectors site to finally find someone with the part I needed.

Hi;
Just out of curiosity, what makes you think you need a new barrel? If you do, it's probably more cost efficient to just buy another #4, since they are cheap and plentiful and I imagine fitting a barrel and headspacing it could cost a bundle.
Grizz

I believe I need another one because the spent case I pulled out of it after the first shot, looked like it had a "puddle" on it. The brase flowed to fill the chamber and some metal was missing due to rust and negligence.

This puddle is the width of the case and just as long.

Basically there is metal missing in the chamber from corrosion, where there should be metal.

Blammer,

Geez...just because a big hunk of your chamber is gone what makes you think you need a new barrel?

Barrels for the No4 are pretty scarce, at least in a condition that would be worth putting on your rifle. Springfield Sporters is back and up on the eb. I am not sure if they have any left or not.

They come up on ebay every once in a while and seems like they sell for $60 to $80 and up. I have seen them go for up to $125. Seems a little nuts when you can still get a rifle for $100 to $200.

As for weather or not you really need a new barrel... The puddle on the brass is probably not that big of a deal unless you are getting gas escaping. How is the accuracy? Do you have overly difficult extraction? Case splits or separation? If not, you really should be OK.
You won't be able to reload the brass, but that is only a problem if you reload.

It can't be too bad,or you'd never get the case extracted.Take it with a grain of salt,But I'd be tempted to clean the area really good with a round wire brush and de-greaser,swab the un-affected area with mold release.cut the head off of a spent case,place in the chamber and blow mold release down the bore.Then fill it in with jb weld or devcon plastic metal.Then call rent a reamer and cut off the excess,,,I think rent a reamer charges 25 bucks a week.you're probably better off just picking up another one and transferring what you like of your old one onto the new rifle,,,wood,sights,trigger,etc.Have fun! Clay

Welcome to the club. I have a German M98 Mauser in 8x57.
I spent the better part of a winter restoring it. I took my time and it turned out beautifully, utterly beautiful. Firing it produced the moment of truth. That barrel was shot to all hell. This is quite common with the military rifles. Best wishes.

Cal - Montreal