The hammer/main spring tension should not have anything to do with the rear trigger and it pulling hard to set.  Although, it could be the reason why the set triggers are not kicking off the main rifle sear.

Since this sounds like a new rifle, the best thing would be to call CPA.

But, a couple thoughts anyway.

Does the hammer cock okay to both half and full?  

The spring you shimmed will definitely reduce the pressure but, as you found out, it is a balanced spring and needs to be properly setup.  To heavy and it’s hard to pull, to light and it won’t kick off the sear.  My first questions answer, could determine the kick off force required if the main rifle sear is hanging up, but this is a long shot and probably not the issue.

If the rifle is new, another long shot for the hard rear trigger pull, could be the set trigger sear.  I don’t know this for certain, but if the front extension on the rear trigger was to long, (not adjusted properly) it could be dragging as you try setting the trigger.  That extension needs to hook under the shoulder on the front trigger, shown by the red arrow in the first picture.

The second picture is the rear trigger.  #1 is the extension and #2 is the surface the trigger spring pushes against.
Bob

Check and make sure the main hammer spring is not hitting on the stock. Pull it off and check for a run mark and if it sets easier with the stock removed.

joelpend wrote on Jul 17^th, 2026 at 8:46pm:


That front trigger should move back as the rear trigger is set.  Does the front trigger pull easy…unset?  If you hold the front trigger back, as far as it will go, does the rear trigger change any? 

Might be best to wait for the call back but, if you want to try it, pull the trigger assembly and see what it does out of the frame.  Remove the sear spring and sear.  Keep the set trigger spring in place and you should see exactly how everything is working.  This is a top picture of one I made so it might be slightly different than yours but still work the same.
Bob