Reply To: SPA PR900W review – a great super cheap PCP gun
Dan, as I mentioned above, their is a way to get a flatter shot curve but this involves turning the power down significantly which also reduces efficiency (the shotcount stays the same). With that sub 12 fpe transfer port, you spread is only about 30 fps because the airflow is getting choked and that results in more or less the same power for every shot as the rest of the air from every shot is probably released when the pellet already exited the barrel (and therewith wasted). The only other option is a regulator but I doubt that it would be possible to fit one in there so its not a viable option. The action (hammer) is sitting directly in the back of the air reservoir. I didn´t examine if there is a possibility of unscrewing the back side but I really doubt there is.
I do only have the sub 12 fpe transfer port and the high power one but it would certainly be interesting to make an intermediate one that still chokes the airflow for the higher powered shots but doesn´t affect the first low powered ones too much. This would probably result in a flatter shot curve and compromise a bit on energy. Lets say you find the right size for the air transfer port with 0.10″ or so and get the rifle to shoot at 700 fps. the spread would probably be 670 – 740 or something like that and the energy would average somewhere around 17 – 18 fpe.
Anyway, for backyard pest control, a sub 12 fpe rifle is more than enough but for the distances of back yard shooting you also don´t really need a narrower spred. The POI shift will be bearable up to about 25 yards.
What I do with unregulated rifles is that I simply make a diagram of pellet impact point at various distances over the useable fill and when I´m down from 200 to 150 bar I know the rifle will fire faster so I compensate for that by holding over/under.
This rifle certainly isn´t the best choice for field target or benchrest shooting but it makes a really good hunter and plinker.