Here we go...
I'll try to make a convincing case to do what I do (which naturally is the best approach in my opinion
):
-When ordering aftermarket parts, I try to buy absolutely everything I might want from that particular online store at the same time to save on shipping; I also try to bring friends in on group buys. The idea here is that it costs roughly the same to ship one spring or 20 so if you order springs one at a time, you end up with as much into shipping as you do into springs.
-Next, call it laziness, call it having two sons in diapers and therefore very limited free time, but I try to limit the number of times I take a particular gun apart so I lump together mods. This could also be because I have owned many guns and done many mods, so it's not as exciting for me; if this is your first foray into home gunsmithing the tinkering may be the fun of it. One thing to keep in mind however is that the more times you disassemble the pistol, the higher your odds of destroying/losing a pin, or slipping with a punch (those of us with large collections can all remember a gun we sold because we could no longer stand the sight of a mistake we made).
With regards to the hammer spring: I have never actually owned a 75B, although I have owned many clones and also a Tactical Sport, but from what I hear, Bs with 13# hammer springs are prone to light strikes with the stock firing pin/FP spring. I run 13# hammer springs in all my guns and have never had a light strike, but all my guns share the same full width hammer as the Tactical Sport. The bulk of the CZ pistols use a narrow hammer (maybe someone who knows can tell me why?) which has less mass, ergo require higher velocity to strike the inertia firing pin hard enough to ignite the primer. The most common solution to this is to use a longer firing pin and or a lighter spring; I also suggest the option of widening the notch in the slide and using the full width hammer of a Tanfoglio or Baby Eagle (blasphemous I know!). I actually widened the notch on an SP01 slide I use on my Tactical Sport and it worked great. To conclude if you want an improved DA trigger pull without a big project, I would start with a 15#, although while you're at it, it's not a lot more money to order a 13#, 11# and 8.5# too!
Recoil spring - there are clear camps in the recoil spring debate: heavier than stock and lighter than stock. A heavy recoil spring slams the slide shut faster than a light one, but it takes longer to open, vice versa, with the light spring. As far as recoil, I don't know which is less/more, but spring weight can certainly change the feel of the recoil; the best way to reduce the recoil is to remove weight from the slide. I'll tell you the best, non-partisan way to pick your recoil spring weight: bring the target in to a distance at which you feel comfortable you can get two fast shots on the paper, then take careful aim and pull the trigger twice as fast as you can, don't even reacquire the sight picture (obviously the less you disturb the gun while pulling the trigger the better). The first shot should be dead on, then if the second shot is high, you could benefit from a heavier recoil spring, if the second shot is low, you could use a lighter recoil spring. The idea is that a spring which is too light doesn't bring the gun back on target fast enough and if the spring is too heavy, the muzzle dips as it goes back into battery. Repeat this over and over again until you have a clear pattern; the more comfortable you get with the trigger, the more consistent results you will see. When I tried this with my Tactical Sport, I have a bunch of springs all lined up, some heavier, some lighter; the stock recoil spring (14# I think) actually worked perfect! Double taps at 7 yards withing an inch of each other. To check the theory, I did the exercise with all the springs I had and they all behaved as I expected. Pretty amazing!
