just prior to becoming retired my sgt. & I implimented prefered carry for our 55 man department.
We established standards such as minimum caliber, .380, maximum caliber .45 a.c.p. for autos, and .38 spl. / .357, for revovlers.
Max barrel legnth 6" and so forth.
We also set stadards for quality, no Rossi, F.I.E. etc.
The officer would purchase the weapon, demontate proficiency with it and could carry same on duty. We set standards for bug & of duty weapons & ammunition also.
Standard issue was the Smith M-66 4".
Many officers carry Kimber, Springfield & Glock. Many were content with the M66 issued revolver. Issue ammo for the M-66 was the .38 Spl. +P 125 grain
Reminton or Federal h.p.