The "right kind of bolt" is a shear bolt.
Specifically, the shear bolt your snowblower manufacturer specifies for that location, since not all shear bolts are the same.
It is deliberately designed to break easily. It's a mechanical fuse. It costs a small amount and prevents breaking other parts that cost a large amount. It is sacrificial protection.
To prevent breakage of the shear bolts, you stop overloading the blower (go slower, take less of a bite, avoid blowing rocks), or you do the classic "replace the shear bolts with regular bolts" and instead of breaking the shear bolts as designed, you break some other more expensive part of the snowblower that the shear bolts were protecting by breaking first.
As mentioned in comments, you might also be seeing a need for lubrication (or adjustments,) lack of which is causing loss of performance and abetting the overload condition. It's also possible (but not the most likely option) that your shear bolts were replaced with incorrect ones that were actually weaker than the correct ones.
Buy lots of shear bolts when buying more. Many recent blowers actually have spots to hold 5-6 spares right on the blower itself - they are meant to be easily replaced. You may have some of the right ones sitting in a bag of maintenance parts included with the blower when you purchased it.