I have an IWI Zion 15 rifle. I noticed it was slinging brass against the deflector pretty hard and makes an odd sound returning to battery. I asked IWI what would they suggest as far as a buffer weight, buffer spring or possibly a lighter ejector spring. They said it was under gassed and to try using 556 ammo. I told them I reload with 55gr fmj a little below max suggested charge. The response was "We don't recommend using reloaded ammo. Try a box of 556 ammo and see if it functions correctly." I'm going to try an H2 buffer and see if that helps.