Geco should be fine, but be careful with Hobbys as they are considerably larger at the tail and are hard to seat correctly with your funger or thumb. They are also heavier so will have less velocity, especially with such a low powered gun.
We got a sample tin of H & N Econo with our last bulk order of Gecos & Hobbys and the general impression in our club is that they are a more consistent size compared to Geco. Our next bulk order will be Econo.
Walther CP-2 Match, FAS 604 & Tau 7 target pistols, Smith & Wesson 6" & 4" co2 pistol, Crosman 1377,
Baikal IZH 53 pistol, Gamo CFX Royal,177, Umarex SA-10 CO2 pistol.