SMLE No.1 Mk.3* Locking lug surfaces

Hello, Im working on remedying a severe headspace issue with my Canadian 1918 SMLE. The previous bolt was not matching, produced excessive headspace, and seemed very worn. I recieved an extremely good condition aussie bolt from a bloke online. I am working on getting it fitted to my reciever. The long lug barely engages, and the small lug doesnt engage at all. I understand the next step is to remove meterial from the long lug, until both lugs are evenly bearing, but I dont know of the best way to do this. Jewelers file, fine sandpaper, fine stone? This will be my first time working with locking lugs, so I intend on taking my time, to end with the best result for me and my rifle.
I appreciate any responses

I suggest that you review these threads:

https://www.milsurps.com/showthread.php?t=20094

https://www.milsurps.com/showthread.php?t=39360

https://www.milsurps.com/showthread.php?t=31793

Also note that, for MOST No1 rifle production, there was ONE size of bolt-head.

HOWEVER, there was enough "tolerance" in the production method to functionally produce a small "range" of sizes. The entire thing was classic 19th Century hand-fitted craftsmanship, because simultaneously, the process involved:

1. Achieving nominal bearing on the right and left locking shoulder and lugs,
2. Having the bolt-head correctly index to the bolt body,
3. Having the bolt body and bolt-head assembly achieve headspace spec with the barrel.

The helical locking shoulders on the body were cut to final dimensions using a hand-driven "shaving tool" running in a special jig that provided the guide for the helix cutter, There was an incredibly expensive, specially-hardened, "master bolt" used to evaluate the location and accuracy of the finished shoulders. There was an "allowance of a whole FOUR thousandths of an inch offset between the shoulders. The tolerances on the locking surfaces of the two lugs on the bolt body were also VERY small.

Bear in mind that some of this "setting up" of headspace, engagement, etc, involved the firing of proof rounds to aid "seating". Wild times!

The only "special" bolt-heads of my limited acquaintance are the small run made at Lithgow post WW2. These were analogous to the "numbered" bolt-heads for the No4 rifle and appear to have been intended to keep Australia's fleet of rifles going until the "new" cartridge and self-loading rifle were well in place. I have never actually noted one in the flesh, but have references to them in a couple of slightly fuzzy copies of "issue" maintenance documents.

Double Post!!

The way I would do it, if doing by hand, would be to cut the base off a fired case, find a suitable coil spring to go up inside it, butting against the case neck while pushing back on the bolt head face. Lapping compound on all four surfaces (unless two look "high"), and work the bolt handle up and down allowing the spring to push the lug bearing surfaces together for as much of their travel as possible.

Anyone who has worked with lapping compounds will know how surfaces look when they start to wear in to each other.

Slow, and not much fun, but much less likely to screw things up than the alternatives, in less than experienced hands.

IMHO ;)