Great Crouton
Below is a new unfired case on the left and a fired case on the right, the biggest problem the Enfield rifle has are cartridge cases not made to military standards. And the sizing dies that are set up for American civilian SAAMI standards. (and a chamber I have never seen)
The amount the case is sticking above the Wilson case gauge below is how much longer the Enfield military chamber is. In 1914 the British reamed the chambers larger in diameter and longer in shoulder location to make room for the mud of Flanders fields. (muddy dirty trench warfare)
Below is a animated illustration of what happens when you fire a civilian .303 cartridge in the military British .303 Enfield chamber. In the photo below I'm holding a fired case in the die with my little finger. Meaning all this die will touch when sized is the shoulder of the case and following this you will need to neck size the case also. If you use a full length resizing die to bump the shoulder back you may over resize the base of the case.
If your serious about reloading the Enfield rifle then the first time you fireform a new case, then slip a small thin rubber O-ring around the rim. This holds the case against the bolt face and keeps the case from stretching.
After the case is fire formed for your chamber then only neck size your cases and let the case headspace on its shoulder and not the rim. Again this method holds the rear of the case against the bolt face to prevent stretching.
When the case becomes a tight fit and excess force is needed to close the bolt you can use a .303 British case forming and trim die to bump the shoulder back for chamber clearance. The case forming die is oversized and the "fired" case below is being held in position with my little finger. Meaning when the die is setup "only" the shoulder of the case will be touched and not the body of the case or the neck. After bumping the shoulder of the case it will need to be neck sized for proper neck tension.
When fire forming your cases with the O-ring make sure you grease the locking lugs to prevent lug wear and do not use too big of an O-ring that excessive force is required to close the bolt. Using the rubber O-ring has the added benefit when being compressed that it centers the rear of the case in the chamber as the O-ring is flattened. This improves case alignment in the rear due to the chambers larger diameter with cases that are minimum base diameter. Meaning better accuracy with your reloaded ammunition.
Now I'm going to go with what maple_leaf_eh said, "
There is a finite quantity of No.4 T Enfields (29,000 or so), but millions of common battle rifles". and if it was me I would find another Enfield rifle to shoot.
It is your rifle and you can do as you wish with it, and you will always have collector and shooter opinions in any forum. BUT your rifle has not been in the hands of a trained armourer in a long time and if the wood has dried out you could damage the rifle the first time you pull the trigger.
