The pressure curve on the 17M2 is faster and higher than a 22 rimfire round.
There have been a lot of reports of burst cases when the bolt and springs are left as stock.
Most of the conversion kits available now include either a heavier bolt, or a weighted bolt, and heavier spring.
P&D had a set in stock, last time I was in, a couple weeks back. It included a barrel, and a recoil spring/guide rod assy, with a oversize knob for weight.
The HMR is interchangeable with the 22 Magnum, not the Long Rifle. Have not heard much in the way of issues with the swap on the HMR/22Mag.
Cheers
Trev