Another Enfield ?

Hi all. I just picked up a No.4 MKI 1943 British 303 rifle at an auction. No one was bidding on it so I took a chance and bought it cheap. Looking down the bore, the inside of the barrel looks brand new which got me wondering if the barrel had been replaced (possibly in another caliber). There are very few markings on the gun. It is a frankengun with no matching serial numbers and the only markings I could find were the Date on the band behind the receiver and an O in several locations ie: bolt, receiver band, receiver. the bands on the forearm are stamped VNS.
I guess what I am looking for is if someone can help me identify if this was an armory rebuild or a garage monster that someone decided to dump. What is the best way to check the caliber to make sure it hasn't been rechambered for .308 or .30 carbine?
After reading the below post I will be taking the fore arm apart to look for holes. Thanks for any input.

 

Well, I finally got the rifle checked out and took it to the range. What a sweet shooting rifle. I have to play with it some more to get it sighted in, but the first five rounds I shot all hit in the vitals area of a deer target at 50 yards. The recoil was mild compared to my Mosin-Nagant and the action was much smother too. Now I just need to find someone with ammunition on hand so I can spend a day at the range getting comfortable with this fine old war horse.

 

Yes, it was the original .303. John, if you happen to remember where you saw that ammo deal, let me know. I found some locally, but they wanted $31 for 20 rounds! I just love how smooth the action is compared to some of my other old military rifles. Does anyone know where I might find .303 stripper clips?

 

Thanks for the tips. I just got 100 rounds from Sportsman's Guide and they seem like good quality rounds.