I voted 22 mag, and yes I'm biased because that's what I use. You can use 22 mag solids that'll do very little damage to the squirrel, but I usually use 22 mag JHP (winchester silver box). They make a dime to nickle size exit hole and you don't have to worry about runners. Also, the bullet holds together, no copper fragments getting into the meat. An off shot and they still fall right away and don't go far. I usually only eat the back legs so that's all I care about so I usually go for a quick chest shot. Much larger target than the head. The rest of the squirrel become my dog and cat food and gives them an hour or so of enjoyment trying to tear off the squirrels really strong hide to get to the meat.
I also use the new high velocity light weight 22 mag bullets (remington premeir 33 grain vmax, Win black box supreme 34 grain, CCI TNT 30 grain all at 2100+fps) on larger varmints like possums, skunks, and racoons around the farm and plan on using them for coyotes out to 100 yards. I'm very impressed with the new 22 mag ammo. My 223 is great over 100 yards but hard on pelts under 100 yards. My 22 mag should be a good rifle to grab when I'm hunting thicker areas where 100 yard or less shots are all I'm going to get. I wish I could report on it's performance on coyotes right now but last year the few time I took it I was skunked all but one time and flat out missed...
Anyway, the 17hmr only comes in explosive varmint rounds so far. The new 20 grain ammo had me hoping but from what I've read the 20 grain ammo is less explosive but still too explosive for eating the meat.
I can't say I've seen either 17hrm bullet performance in person, but I have seen what the small 30 grain explosive 22 mag rounds do on a squirrel and it's carnage. :eek: Even head shots are hard to look at while you're skinning them out. Blood everywhere.... No brains though, they're scattered over the ground. I image the 17hmr is the same. Carnage. But that's what the 17hmr is for, varmint carnage right?
If you have to choose 17hrm or 22 mag, I choose 22 mag because of wider ammo selection at this time (who knows in 1 year to 5 years). Between 22 mag and 22lr, if you're only after squirrel and rabbit, 22lr. If you're like me and want 1 gun for small game up to close range preditors and other varmints, I'd get the 22 mag. I put in alot of time with my 22mag and know it well. I have 22lr's but use the 22 mag most of the time for small game for the trigger time, target time, hunting time, etc. "Beware the man with one gun" they always used to say.
Oh, on skinning the legs, I cut the skin on the inside thigh area and cut a hole to the top and bottom of the thigh. Then I peal the skin back and around the other side of the leg and pull it down past the"ankle". Then I cut the tendons and such around the ankle and eventually gun my way threw the joint. Then I cut the top of the leg muscle down to the hip socket and once the hip socket is cut to all the way around I give it a twist and tug, then cut off the remaining tendons and it's free. Repeat on the other leg. Then the rest becomes dog and cat food. In the end nothing is wasted.
Again, if you're a "serious" squirrel hunter head shots are the goal. I guess I'm not a "serious" squirrel hunter by those standards, but I don't waste anything either. If you don't have some way to use all of the meat then you need to eat it. There's nothing wrong with the rest of the meat, just alot more work for not much more meat IMHO. So whatever you do, don't waste any of it.
Good luck and safe hunting!
Here's a pic of my nef 22 mag sportster -

Overkill for squirrels... but it's used for alot more than squirrels. I have a thread in the nef rimfire forum with details on the rifle.
later,
scruffy