The folks who man the phones at Savage aren't gunsmiths, they're phone jockey's being paid a little over minimum wage at best. Most of them know very little (if anything) about firearms. They know how to punch a SN into the computer to pull up a parts diagram and generate an order, that's about it.

Far as I know the 3-piece spring is what comes in the Axis, 11/111 Trophy Hunter and the slug guns. I haven't messed with a M25 in six years, but know the one I reviewed at that time had the one-piece spring the same as yours.

To me it sounds like a weak firing pin spring or there's excessive drag somewhere that's limiting firing pin energy.