120gr 32-20 hard cast lead for downloading

I inadvertently just got dropped into the light load thing.  There's numerous ways to do this, one being what you're doing.  Missouri Bullet company and others sell their .313" coated cast bullets in bulk at about $.08 per bullet.

 

American Reloading is another company that sells blemished/pulled pistol bullets also in bulk for about $.10 per bullet; you have to keep an eye on their website because everything is based on availability and they sell out fast.  If you are quick on your feet you can get bullets like Sierra Matchkings that are seconds due to surface staining blemishing at less than half what you would get them in a store.

They even have .311" once in a while:

https://americanreloading.com/collections/311-cal-303

I have a Thompson/Center .32 caliber bullet mould for the Green River barrel I bought for shooting my .54 caliber Hawkin when I decided shooting gophers with 540 grain hunting bullets was harder on me than it was on the gophers.  It drops bullets which after being powder coated should work just fine.  That particular mould is now unobtainium since T/C passed into history and the small bore muzzle stuffer crowd pay ridiculous prices for them when they show up for sale on EvilBay.  So much so that I've thought of casting a a few thousand, enough to get me through whatever time I have left, then sell the mould to somebody who desperately wants one.

I'm not a Lee Enfield historian, but as far as what the US military called "gallery loads" goes, those low powered indoor/short range training rounds were common in the US military since the 30 U.S. was adopted by their military.  Our modern version were .22 rimfire inserts issued for our FN FAL rifles (made for FN by H&K, of all people).  FN collectors pay big bucks for one of those complete and in the box.

I'm not aware of whether the Brits, Aussies, etc developed gallery loads at some point after the .303 British cartridge was adopted.  Can't recall seeing anything like that in Canada.