dahermit, Sierra's rep said the reason was due to a lot of requests for cannelured 22 caliber HPMK's for use by folks in their AR15 type semiauto rifles who wanted to crimp bullets in their reloads. The bullet's cannelured so crimping can be done more easily. So, to me, it was another way for them to sell stuff keeping customers happy and make money. I believe Sierra's folks making and testing bullets know very well that any crimp on rifle bullets degrades their inheirant accuracy by adding another variable to the ammo that'll never be zero in magnitude.
I think it's like a master gunsmith asked to build a match rifle that'll compete with the best of them but the customer insists it use a Shaw or McGowen or Green River barrel.