This Guy says a Lighter valve spring won't keep valve closed,or just the Opposite
of whay you just said!
I've put #6 Hillman Springs in My Reg Valve 13XX's,Just had to remember Marioto cock gun Before Pumping!!
I say with a Lighter spring ,the Air pushing the check valve back duing pumping is
better, beccause when you Squeeze trigger,firing the gun reg (Stock)Hammer spring
will send hammer with adequate force to Hit exhaust valve rod to open up valve faster,
dumping all the air up thru TP to send Pellet! as long as TP,exhaust channel is Modded