CJ gear works fine for rotators just make one simply mod , add J- B weld above the spring /scissors to the gear leg , this will keep them from turning under torque on landings and take offs .I have over 7 pairs of CJ , no problems at all and trust me I am not a "greese landing pilot "
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Howveer you absolutly have to make this mod or the gear will twist under load and bend and break the scissors .
As far as the 615 , its a continued reinforcemnet that robart should stick to giant scale , I gave them one more shot after years of swearing away the tiny set screws , drilling and hammering to assemble your gear and spending over $225 combined [:@].Thats why I went to CJ to start with , i do agree that sierra is the best , but be prepared to spend $295 for gear with scale scissors no air support so add another $39 for a robart air support kit