Shooting the revolver troubles

I started shooting the revolver this week after being away from it a while. I used to shoot it double action and wasn't very good at it, so now I'm trying single action and doing better in slow fire and timed. I shoot an older 4' 686 with a weigand mount and ultra dot II. I had Randall Fung make me some of his Euro style single action grips back when I had wrist surgery, they made it easier to hold and shoot.
   I'm dry firing more with it this week, I'm realizing that the hammer takes longer to fall than a 1911. When I try firing rapid fire I get about 3-4 shots off and call them left. When live fire maybe 4-5 shots and spread them in the white, usually first 2 are in the black.
   Since I'm shooting everything single action and it's had action work and a 2.5lb trgger pull, can there be anything done to speed up the hammer fall time (lock speed). I'm thinking a heavier main spring or is technique more in line with this issue
   I've tried doing everything like I do with 1911, except in rapid fire it's tough to cock, put pressure on the trigger, and get dot on target since the trigger's lightweight. I find myself snapshooting as the dot gets above the black, some okay some not. There's not much written on single action fire with a revolver and I've got a hunch that more dry fire is in order too, but that rapid fire is a tough one to figure out.
  I'd like to here any suggestions on single action grips too, maybe grips without the adjustable shelf.
Stan

It's possible the mainspring has been thinned to lighten D.A pull.

Get Wolf ribbed back mainspring and a new factory mainspring screw and tighten it up. Your s,a pull may be faster and not much heavier.

If you're coming to the match at Cedar Rapids this weekend, bring the revolver and we'll try to figure out what is going on.

James, I think you hit that very well, I pulled the grips and my friend Gary did in fact file the edges of the the main spring. I'm ordering a new   ribbed mainspring tomorrow and a screw. James, it wouldn't make much difference with the rebound spring, since I'm thumbing it, I think he changed it also. 
  Ralph, I'll try to make it there Sunday since I missed Milan last weekend.
Thanks, Stan

Right, the rebound spring would only affect the D.A pull and trigger reset.

I dropped my SA pull by 1# changing rebound spring. S&W Mod 14.

It will marginally impact your single action pull,

It will dramatically impact your double action pull.