Maybe it is supposed to shear like that...?

I have a 5' Competitor Cutter I pull behind my Kubota MX5100. It seems to do a pretty good job cutting, but I have a tendency to shear pins quite often. I am fairly new to the tractor business and from what I am hearing I shouldn't be shearing the 1/2 inch bolt nearly as often as I am.

I have been using the bushhog for some fairly heavy cutting here recently and during an hours worth of work I manage to shear around 5 bolts. I cleaned up around the bank of my pond and didn't shear any pins but when I started cutting some heavy stuff (1"-2" trees/shrubs), I would only do about 15 minutes worth of cutting before I would have to replace the shear pin.

Maybe it is supposed to shear like that...? I had a friend come by while I was working and I asked his opinion. He had his bush hog hooked up to his new Kubota (which uses shear pins) and he said he has used the same shear pin for a long time. The funny part is when he left my place he was back in about 15 minutes to show me what happens when your pin doesn't shear. He busted the yoke on his drive shaft.

Bush hogging with my Modern Attachments Competitor Cutter