Tuning Brocock compato Caliber change

I don't get the answers here. I do a LOT of cal. changes on many guns. All that is needed is mag, probe, barrel and open the ports a bit. not that expensive what so ever. I make my own probes. 

Next project is the Uragan. From .25 to .22 and later to .30. 

Barrel, what, 120 bucks? mag, 100 or so, probe, 25 bucks and if a machinist is needed for the barrel turning, another 100 to 150 bucks. So 345 to 395 max. How is this half the cost of the gun? 😕

Knife