For benchrest best bet is going to be the precompressed (scuba ) guns as listed prior. To save alittle green the predeccessors to these were powered by CO2 bulk fill. My reason for stating this is no moving parts cept hammer and valve. The co2 vs pcp in the top match rifles give nothing up to each other. An advantage to co2 is the constant velocity due to the consistant expansion ratio of co2 liquid to gas vs pcp where each shot reduces the available pressure which is the reason for the regulators in pcp guns to minimize the velocity drop shot to shot. These rifles were designed with the standard 10 meter target distance in mind. Various tests on pellet velocity have proven that at 10meters the optimum velocity is aproximately the mid to upper 500fps (about 6 ft lbs) with the 8.9 grain match wad cutters. At the extended range of 25 yards the platform of the guns is still sound, but the velocity drop off of the pellets might be a concern. The field target boys have developed their sport to quite a refined level. They shoot out to 50 yds or more. using 10 grain 177 dia pellets and power plants developing up to 20 ft lbs with the pcp system. Co2 in this arena is limited as it has a finite expansion ratio, the best way to gain velocity here is a longer barrel. So perhaps the field target version power plants in pcp are a more correct choice. The rub is that at best these field target units only get up to 30 shots from a 200 bar or so charge (2500-3000psi) at optimum velocity. (Note match pcp units avg. 200 shots/charge) The field target stocks for the most part are not condusive to benchwork out of the box so one has to be a little creative in that area. With the exception of a unit produced by Tim at Mac-1 (in Calif., field target type) all the top guns are of overseas mfg. match or field target types. Hope this helps.