JR I just ordered a LWD 9mm conversion barrel for my G22. The purpose was to save $$ on ammo. WalMart has 115gr 9mm UMC cheap, but I read here that some 9's have trouble cycling 115 gr. ammo. So wouldn't a gun set up for .40 cal have even more trouble with light 9mm's? The recoil spring on my G22 has "5579" embossed on the base of the plastic guide rod. It cycles my .40 UMC 180 grain ammo fine. (Throws the casings about 10 feet.) Will it be too heavy for 115 grain ammo in the conversion barrel? If so, what spring would you suggest?