New Indoor Load

I'm using up some of my old bullets and have about 2000 of Magnus 155 gr swc bullets I want to use up. I have 2 pistols to try now, a AMT Hard Baller with a slide mount dot and a Clark Heavy Slide with a slide mount dot. I did have a load for a Springfield frame mount that work good with 3.5 gr BE and 10 lb spring, but a slide mount might be a little more difficult with that spring. My question is can a 7 or 8 lb spring be used reliably or would there be issues involved with them. I liked how soft and reliably that load shot in the Springfield at 50' and 25yds and want to keep it 3.5 for either slide mount pistols. If there would be issues of using real light springs then I'd have to up the charge more for some stiffer springs. I just don't know what problems I'd be getting into, thanks for any help.
 Stan

Since the recoil spring is more about solid consistent lockup, I’d stick with the 10 #’r
That being said, my Clark slide mount requires 4.3 BE to cycle 160 he cast.
But 200 go with 3.5 BE works fine.