We have 2 different 100m competitions in The Netherlands. But on both of them +12 fpe guns are used. Minimum energy used is around 30fpe.
Indeed they are connected to large external air supplies. For two reasons:
1. Heavy air use (as you mentioned). The guns that are used can produce 5-30 usable 100m target shots on the own supply.
2. More consistency in velocity of the projectile (although some guns are internally regulated)
Here some results from another 100m competition. As you can see, in this one guns are used with calibers that are being used in the UK on -12 fpe guns. In our competion these guns (for instance BSA) will produce app. 30fpe.
ATB
Emi