Originally Posted by eel one

I Have been running a G&P 7mm reinforced V2 box with a M130 spring at a ROF of round 30 bb's/sec for 1½ years now. No problems with cracks so far. I realy dont know why, but it seen that it takes scandinavian people to make a proper upgrade on an AEG, if you whant it to last. I rarely hear of and never see any cracked boxed, in the danish airsoft community. But we might be a lucky nation? If you do the job right first time, when upgrading, you can have a gun running for round 40-50.000 rounds before havning to do anything more that installing a new piston.