It appears you're referring to a non set trigger, so the easiest way is to reduce mainspring strength. Too heavy will make cocking the hammer very hard, and could even result in pierced primers from a heavy strike.
I'd start by not taking too much off at first. Just rounding the corners of the mainspring, and then try it with just a primed case to ensure it strikes hard enough. If it needs more I use my belt sander to thing the thickest part of the spring, and keep a cup of water handy to cool it so it doesn't get too hot.
Once you've lightened a mainspring for a Roller it goes faster the next time. Just be careful not too get too carried away before trying it.

I would only lighten the main spring as a last resort.  That way is full of potential side effects, and is not likely the cause anyway.

The very first thing I would check for is the mainspring hitting the cross screw that holds the trigger guard on.  If you take the buttstock off, and look in from the back with a good light, you may be able to see if that is happening.  If it is, the effect is that the hammer has to bend the last 1/2 inch of the spring, not the whole spring, so it makes the spring appear harder than it is.  This is caused by the main spring not having quite the right curvature, and can't be corrected in the spring easily.  (or too long a trigger nose) If you have spare parts, I'd try several springs and see if one works.  That would be the definitive diagnosis there of a bad spring.

I've often seen this problem corrected by grinding away about 1/2 of the cross screw diameter in the area that the spring hits.  By carefully marking the top side with the screw tightened, you can determine which part to grind away.  A more elegant solution would be to convert to two screws, like a sporter action has.  That would of course require modifying the receiver and the trigger guard assembly.

Another thing to try is a shorter trigger.  If you have spare parts, again try switching them out.  If a shorter trigger fixes the problem, the original can be shortened, but it will then need to be re-case hardened to work correctly when you're done.

Good luck!

SSDave was right.  The mainspring in the gun was chrome plated and much thicker, especially at the end that rubs the base of the hammer.  The spring was  contacting the rear trigger guard screw when being cocked.  I put another spring in the rifle and Voila!  It now cocks MUCH easier.  I guess I'll use the spring for making a bowie knife, lol...   Thanks SSDave!   Thanks also to the other gentlemen that offered possible cures.