Why the sear? Is the current one damaged? Don't replace current parts unless you fear failure. The springs are available, the only question is what weight do you want? The heavier ones are for high pressure loads meant to make majors in competition... The rubber buffers aren't needed if your springs are good. You can get GI replacement springs and they'll be fine. Don't get the Wolfe brand over power types, they can be trouble. Ask for a full replacement set and you'll change them one for one. Use standard ammo, perhaps Federal 230 gr ball would be available to you? It's about as good as can be had and close to gov't spec. It's clean...