Over the past 8 years, I have answered a LOT of threads with complaints about Failure to Feed in the Lee-Enfield rifle.
Nearly all of them could be traced to magazines being swapped, dropped and plopped instead of being left IN the rifles.
Properly fitted and adjusted, they will feed flawlessly even with crappy modern ammunition which lacks the gentle RIM BEVEL you find on early military ammo. That Bevel was there to enable misloaded rounds to slip OVER the lower rounds..... and feed flawlessly.
IN the rifle, the feed lips cannot get bent. They are only thin sheet-metal and they bend easily, especially when DROPPED. Or knocked off the table. Or diddled with by some genius who knew more than James Paris Lee. Magazines were a critical and expensive component. They were (until the deep-drawn Number 4 Rifle Magazine came out) hand-made and individually-fitted to a particular Rifle. They were not serialled because it was recognised that they were somewhat fragile. Unit Armourers maintained a small supply of Magazines but these were not SPARES: they were REPLACEMENTS and were to be fitted BY THE ARMOURER.
I have seen guys show up at matches with pockets bulging with magazines in order that they might do a 'fast reload', dropping magazines on the ground, dumping them from the rifle and slamming in a fresh one (if they can get it in without spraying live rounds all over the firing-point), stomping them into the snow as they go to the next firing-point.... and then cursing that rotten old Lee-Enfield because the "F%%#^*ing THING DOES NOTHING BUT F&^%$#G JAM!!!". I have even had a guy BORROW 3 mags from me for a match. He even gave ONE of them back. Guess I am just SO lucky.
If you have a CLLE, SMLE, Number 1, Number 4, Number 5, Lightweight, or even a super-rare Australian Number 6, the rifle reloads FASTER with Chargers. That was the reason for the invention of the Charger in the first place: to allow the Magazine to remain IN PLACE where it could not get the Lips damaged.
Supplying spare Magazines was TRIED and did not work out, for the reasons above. The Lee-Metford Mark II had the single Magazine actually CHAINED to the Rifle. It could come out just far enough to be cleaned..... and not far enough that you could SLAM it back into place.
That should give some folks just a TINY hint.