I have been of the opinion that the CZ75/SP-01 safety could be more positive than it is in stock configuration. I have heard others mention this as well, in the case of carrying a CZ safety model this may come more into play then anywhere els. For me this is not an issue being that i prefer CZ decockers for defensive purposes. My safety models are range pistols for the most part.
Regardless of my personal need of this upgrade part, i really like it when i see people offer specialty parts for CZ pistols. I feel that it enriches the platform for everyone involved. In this case it is the CZ Extra Power Thumb Safety Spring. I purchased a few of these springs out of curiosity.
I installed one of these spring into my SP-01 safety model to find out. The SP-01 unlike the CZ85 (CZ85 being a CZ75 with ambi controls) has a spring loaded safety detent only on the left side. The right side of an SP-01 has a insert without a spring. In a CZ85 and other short dust cover CZ75s there are springs on both sides, one for each safety lever. So one might get even more of an increase in safety lever tension when installed in a CZ 85 or other short dust cover CZ.
A word on installation. The extra power spring is longer than the original factory part. This makes installation a bit more challenging because you have to compress the spring further to get the safety detent back into place. With the help of a metal probe, it took a few extra minutes to reinstall the safety detent with the extra power spring. While a bit more tricky, installation was easily accomplished. I might suggest leaving the extra power spring for the final touches if doing allot of upgrade work on a CZ. Taking it in and out a bunch of times could get tedious, the stock spring will be easier with repeated disassembly/reassembly.
Factory Spring - Top / Extra Power Spring - Bottom
Extra Power Safety Spring pull weight comparison: These measurements are the product of average of 10 pulls with a Lyman electronic trigger pull gauge. I had paddle safetys (Shadow safetys) installed on the SP-01 so the trigger scale had a better ledge to pull on for more consistent readings.
Stock Spring - On: 1lb, 5oz Off: 1lb, 0oz
Extra Power Spring - On: 2lb, 10oz Off: 2lb, 6oz
In the end the extra power spring approximately doubled the pull weight of the safety lever. As stated above when installed into a CZ85 with two springs, one could expect an even greater increase in safety lever pull weight. I will test this in a CZ85 in the near future and add the results to this post. I assume that the increase in tension can vary a bit from pistol to pistol due to differences in manufacturing.
The purchase of these springs was painless. An email and a few bucks through Paypal. If anyone is interested there is a link below to the
Dsperman website.
http://dsperman.com/