I'm looking for a lighter than OEM spring for a 9mm MechTech carbine... I would like to stay with my 147 grain hand load at just over 900fps, and I get an occasional failure to eject due to the weak load... the factory spring is  5/16 dia .043" wire... I've tried a "hardware store" grade spring of .039" wire, but was deformed just installing it... anyone have an operating lighter than OEM spring?... thanks

Check with Wolf springs.   They have the spring kits for other guns so they may be able to help.

Old slightly "tired" AR15 spring perhaps?

the spring is an extension spring... like the screen door spring if you are my age... I found one on the Fastenal web site... 5/16", 5", .035" wire... I don't know enough about the spring rate of the original.... I e-mailed ISMI and Wolff... ISMI responded in the negative, haven't heard from Wolff yet... letting it sit in the gun safe with the bolt locked back... I really don't want to have to load two different 9mm rounds