What do you plan to use it for?
I got all caught up in the HMR/HM2 craze when they were first released. I have a nice marlin, heavy barreled bolt gun in 17HMR....great shooting rifle. With a little trigger work, it can shoot sub 1" at 100yds any day there isn't much wind--and that's with a 4x-12x scope. A great round for target work! A little expensive for the rimfire world, though. As mentioned, out to 100yds on paper the HM2 is almost half the price and every bit as good.
For hunting...
I can't comment on the HM2, but I can tell you the HMR was a big let down. I bought this round because there was a lot of hype (even from the ammo manufacturers) that this round was good up to coyote size game out to about 100yds....and a great round out to 175ish on smaller stuff (ground squirrels, P-dogs, etc).
Truth be told...not so much. (Remember, this is just my experience/opinion).
NOT a good round for coyote size game...I wouldn't consider it on bobcat or coon size game beyond about 75yds. The bullet is just too tiny for the larger "small game." Light weight means penetration is going to suffer, it doesn't fair well against bones, and the tiny .17 bullet leaves a pretty small wound channel when things don't work out like they should.
Soft points and FMJ's are pretty much pointless beyond paper punching and the tinyest of critters...they just don't do enough damage on any of the larger stuff. Penetration doesn't mean much with a tiny wound channel.
I love my HMR, don't get me wrong. It's one of my paper punching favorites...and it's GREAT around the farm taking out crows, barn pigeons, rats, and the occasional mole. I've also used it to dispatch wounded barn cats a time or two. I will NEVER take it in the field if I plan on hunting anything over 10-12lbs....and that rules out almost everything in N/W Washington state. If you're looking for a ground squirrel/p-dog rifle, this might be what you're looking for!
The best thing about the .17 rimfire craze, IMHO, was the kick in the pants to ammo manufacturers to create better ammunition for .22mag fans. Years ago, the .22mag was pretty much a .22lr with more powder--that is, a lot of soft lead (non jacketed) bullets in the 40grain class for weight. Not the most accurate stuff out there...I think this is why the .22mag never created a huge following.
Now, we've got TNT and VMAX copper jacketed (even TOTAL metal jacket-TMJ's) for the .22mag...the .22mag has exceeded 2,200fps.
With the higher quality ammunition, many of our old rifles are able to shoot at/better than MOA out to 100yds. This QUALITY ammunition has put the .22mag ahead of the HMR in my book.
Larger bullet diameter and more weight--better penetration, larger wound channel, and more energy at longer distances.
The .22mag is now my favorite bobcat round. Very little chance of pelt damage, and I feel quite confident out to about 125yds. I've seen what this stuff does to a cat, and I'm a LOT more impressed than the HMR. In my area, shots are usually under 100yds.
And while I'm not one to advocate shooting coyote size game with rimfires...I wouldn't pass up good/clean a shot within 75yds with my .22mag--Mind you, I would NEVER walk out the door with the .22mag knowing I was looking for 'yotes....I'd much prefer a 22cal. CENERFIRE.
The long and short...
HMR is lazer flat and very accurate...great for paper and pests.
The .22mag has come a LONG ways, and beats the HMR in my book for field use--better choice for hunting small game.
The .22hornet is great...but the brass can be a bit of a PITA to reload, and for the noise the hornet makes, I'd just as soon carry my .223 for a little more power (and cheaper factory ammo when I'm lazy/away from my reloading equipment).
I LOVE my contender in .218 Bee!
