I've used brass shims on half a dozen 1899s where it was obvious that the stock had shrunk away from the recoil lug and the tang was digging into its in-letting. Never had one of these crack or have any side to side or up and down movement. I like the shims in guns I don't want to alter in any way. I've glass bedded and relieved wood in less collectable guns. I have 2, .300 Savage Gs with brass shims that I've fired hundreds of rounds in while developing loads, practicing with peep sights and hunting.

I'll show you a "Savage Crack"
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That's what happens when you slip and fall on your Savage. Blew out the side of the receiver, cracked the wrist and tang in-letting.