Would a 13 lb. hammer spring cause light strikes on a cz75b pistol?
Yes, but might depend on the primer you're striking. What ammo/primer are we talking about?
Federal or Winchester ammunition primers will "probably" fire reliably, but others "probably" won't.
As said above, the lighter FP spring and FP Block spring will improve the strike. The 13# or 11.5# hammer spring should fire reliably with all primers up to CCI hardness (and maybe more)if you add the extended FP. Polishing all the action components friction areas will aslo improve the strike. Stickies show where to polish to reduce friction.
+1.
Specifically, Federal primers (whether purchased in the form of components or factory-loaded cartridges) use a different priming compound than virtually all other brands. It is an older formula known in the industry as "basic priming compound." It is higher in brisance (flame) and detonates more easily. I mention this because many, many modified pistols will fire Federal primers reliably, but not necessarily anything else.
You will want to test with a brand with lacquered primers (i.e. S&B) or so-called "hard" primers (i.e. CCI/Speer) to be certain.
As you may have gathered, not all models and production years are created equal. In addition to characteristics from wear/use, older CZs may have had Czech-manufactured OEM springs lighter than their nominal specs. This shouldn't be an issue on a pistol manufactured in this century, however.
