When I first came on in '64, we had a great deal of interest in shooting. But, we had many more military veterans then, some from WW II. Our range was open each month, and mandatory qualifications were twice a year.
The qualification ribbon WardenRoss mentions was an incentive, because there, on the shirt or jacket, was proof of shooting ability. With it came bragging rights. We shot at 50 yards back then. The highest qualification ribbon was 'Distinguished'. It required an average score of at least 97.5% for at least 10 shoots (out of 12) to earn. For people who were competitive by nature anyway, it was natural. But it was challenging.
During the peak of PPC shooting, the '60s - '70s, our medium size department sponsored three shooting teams.
Until about the late '70s, we bought our own revolvers, via a uniform/equipment allowance We had a substantial number of deputies who, rather than buying the most basic available revolvers, opted for adjustable sight 'K' and 'N' frame Smiths (this predated the 'L' frames), Colt Pythons and Troopers/357/OMMs, and then later on Ruger Security Sixes. The decision by the department to purchase and mandate carrying Smith 66s ended the era of carrying personally owned revolvers.
I can't say that half of our department were conservative and half liberal. I would characterize us generally as center/right or center, but not liberal. We may have had some recruits come on with liberal idealism. But, then as now, the same groups that demonize and vilify LE were on the left side of the spectrum. All of the violent social upheaval and riots (now termed 'mostly peaceful demonstrations') we policed then were from the left side of the spectrum. This reality had the effect of causing LEOs to become more conservative. Pretty tough to relate to those seeking to break your head open. This was not just my department, but all of LE with whom I had contact. So from my experience I reject OPs speculation.
As time passed interest in PPC competition and shooting in general waned. There were just too many other demands on time. Besides my LE job, I was also going to school and teaching. Once I had my advanced degree, my teaching commitments further expanded. Our department, along with other LE agencies in the region, placed great emphasis on formal education if one wanted to advance. Promotions were/are intensively competitive. If one walked into an oral board interview and had no degree past high school, and was not working on one, the conversation dried up pretty quickly.
So increasing various professional demands, along with the normal demands of raising a family, took a toll on available recreational (which is what PPC competition was) time.
Because I was teaching AJ classes in (among others) community colleges, I was getting a lot of young people who had graduated high school but who were too young to apply to become LEOs. Since I had a three semester sequence of classes, I got to know most of my students. My observation of them was they were not liberal, but more center and center right. This was regardless of ethnicity.
I taught in these venues until I retired in the mid '90s, and this demographic did not appear to change.
I did see less interest in earning that shooting qualification ribbon as time passed. Early on we still fired from 50 yards. But then the course was reduced to 25 yards max, and the score to qualify 'Distinguished' was lowered to 95%. Bragging rights, and the incentive to earn them, were reduced as a consequence.
Some context: I retired in '94. We immediately moved and live in a very remote mountain area, so I don't know where my old department, or LE in general, is now on any of these issues. Even my AJ kids who went on to LE careers have all retired.