The Lee Enfield is one of the most tolerant when it comes to out of spec head space. I believe the topic to be blown out of proportion.
Many generations of owners dont even know what head space is and has never been of great concern.
The preoccupation with head space seems to be encouraged by reloaders who are really up against all odds when hand loading for the 303 British round. Reloading was not overly popular by the masses when there was plenty of army surplus ammo around. In recent years, that supply has dried up and shooters are now looking to reload as modern commercial ammo is expensive and at times hard to find.
Despite what some critics will tell you, the action design is very robust and it will literally take thousands upon thousands of rounds down the tube to wear the gun out. Designed as a throw away cartridge, the 303 Brit round was never intended to be reloaded, it was a one shot with a disposable casing. The chambers in the battle rifles are generous to allow any manufacture of round to fit the chamber in battle field conditions. The brass will expand on firing and seal the pressure in the chamber. However, this stretches the brass (as it is supposed to do), and makes things difficult when making hand loads and repeatedly resizing a brass case. Eventually the resized brass will work harden and the stretching thins the case and a case head separation might occur.
When the brass case lets go, you might hear a difference in sound of the shot, maybe. Or you might see a puff of smoke at the chamber. The design vents the gasses away from the shooter so most times one will only notice a split case on ejection.
It would be irresponsible for me to suggest to just shoot the damn thing and examine the brass for problems, but that is what some owners do. There is a great deal of pressure generated in front of your face when the thing goes bang.. Potentially dangerous if something is amiss. Safety first!
Some shooters tie the rifle to a tire and fire remotely with a string around the trigger. Some just give it to their dumb assed brother in law to shoot first (here, hold ma beer)...
Clean the rifle making sure that there is no obstruction in the bore. Dry the chamber and bore of oil. Shoot half a dozen rounds of clean new commercial ammo and examine the cases for stretching or other probs.
If you don't reload, just toss the brass in the bucket, somebody will scrounge it from you.
If you do reload, be prepared for a fire hose of information on tricks and tips for preserving your brass and ways for reloading them multiple times.
There is a great deal more to adjusting these rifles than switching out a bolt head, and that knowledge is for the armourer, not so much for the shooter or hobbyist. If the rifle fails the field gauge due to wear from use, then there are likely to be other wear concerns such as worn locking lugs, bolt threads, cam track, bolt way.... A whole can of worms to open. Practical advice is, if it passes the field gauge (0.074) then have at her and bang away.
A 'FIELD' head space gauge and a separated case extractor are two things that I carry in my shooting box, they don't get used very much, but when needed, they are the best to use. I have checked hundreds of rifles with my field gauge (usually rifles belonging to others), only a few failed the spec, and they still shot just fine.
So welcome to the world of the Lee Enfield, it was adopted for Canadian service 1896, has been used in numerous major conflicts and is still serving today with the Rangers.
It is a good design, so don't #### with the gun to improve it unless you know what you are doing.
Your rifle is of classic sporter form. It is part of our Canadian heritage. Rifles such as yours have probably put more meat on the table to feed families that any other rifle in Canada.
You have options and your rifle has great potential.
Use it as is and take a step back in time when hunting.
Restore it back to its original war horse configuration. Imagine what that sight picture has seen.
Or restock it with aftermarket wood and turn it into something really sporty.
