[Unclenick]

Yep. You sometimes see white oxide build up, but without very acidic soil, it's pretty much harmless. Take a look at Civil War bullets dug up from battlefields. Those white crusted mini-balls are full weight, for all practical intent and purpose.

Either cast or jacketed bullets will splatter lead around if they hit a steel plate squarely, but the pieces don't resemble fish eggs or seeds, like shot does, so the birds have little interest, AFAIK? If you have the option and the money, set up traps so you can catch and melt and clean and flux and re-use the lead. Bullets that hit steel angled beyond a critical degree don't dig into the steel, and more ricochet than splatter. Savage makes commercial semi-snail style bullet traps on this principle (though the design takes less steel than the original M1 .30 Carbine snail traps did), and they allow very easy recovery of the spent bullets.

If you can't afford a ready-made trap, but you have some scrap plate, tip it until the steel is struck by the bullet at about a 10 degree angle. If the plate is about 6 times longer than wide, it will look pretty much like a square from the shooter's vantage point at that angle. Catch the bullets in sandbags under the plate. Periodically dump the sand through a hardware cloth sieve to recover the bullets, then re-bag it. Replace the bags as needed.