Virtues of 17 Mach 2
I believe the 17 Mach 2 to be the best cartridge for tree squirrel hunting for the following reasons: Because of the precision 17 grain bullets it uses, it is superbly accurate (just as accurate as the HMR which uses the same bullet), with many guns chambered in this caliber capable of 1/2 minute groups (with no wind). It is much flatter shooting than the 22 LR, and holdover is unnecessary out to 100 yards or more when making head shots on gray squirrels. Out to 100 yards, there is an insignificant difference between the trajectories of the Mach 2 and the HMR. If a 22 LR is sighted in at 50 feet, it is dead on at 50 yards and 6.5 inches low at 100 yards with 22 Standard Velocity ammo and sights mounted 1.5 inches above the bore. The Mach 2 is somewhat noisier than subsonic (standard velocity) 22 LR ammo, and some hunters consider this very important, so they choose the 22 for squirrel hunting (I suspect at distances less than about 60 yards). But, the Mach 2 is MUCH quieter (about like a high velocity 22) than the HMR. Late season squirrel hunting (when the leaves are down) often affords shots well beyond 60 yards, so I favor the 17 Mach 2. The 17 HMR is MUCH noisier than the Mach 2 and blows up squirrels when you hit them. While a head shot with the HMR ruins no meat, it sure makes for an ugly dead squirrel. And too often on ground shots, a squirrel hops just as you shoot, and you end up with a body shot, despite the best of holds and trigger squeeze. The Mach 2 doesn't damage much more meat than a 22 LR. For example, I took a squirrel at 25 yards with a Mach 2 with a shot into its right eye. The only evidence of the shot was a missing right eye and a somewhat bulged left eye. I shot another that hopped at 25 yards, and the bullet struck just behind the right shoulder. It produced a 3/8 inch entry wound and no exit wound and killed the squirrel instantly, with no loss of meat. Finally, neither the Mach 2 nor the HMR ricochets like the 22 LR does--they just vaporize when they hit a hard object at squirrel hunting distances. This is an important safety factor when taking ground shots. IN SUMMARY, IF YOU WANT TO EAT WHAT YOU SHOOT, AND YOU SHOOT AT DISTANCES MUCH BEYOND 60 YARDS, USE A MACH 2. Regarding squirrel rifles, if you can afford one, get a Cooper Firearms Jackson Squirrel Rifle in 17 Mach 2 (with AAA Claro walnut stock with rollover cheekpiece, inletted sling swivels, and fluted stainless barrel) like mine. It is as nice a rifle as can be made by humans (great trigger and superbly accurate), and if there are no squirrels about, you can still have a good time just admiring the stock in the sunlight. This rifle (along with my Springer Spaniel and side-by-side shotguns) helps bring meaning to my retirement!