Squirrel hunting is something that most of us who weren't born in cities grew up doing. As a kid, opening day of squirrel season mean't there was a lot of fun to come over the next few months as it was followed by deer, rabbit, and all other game hunting seasons in my state.
It also mean't a lot of fun would be had that day as these little creatures would give me many challenging shots as they started the game of hide and seek that has been played for many years with humans.
Most of the guys I hunted with used shotguns with high brass #6 shot. My dad was on of them. When I asked him why he cheated by using a shotgun his response was "they just won't be still".
A couple of us, that needed a little more challenge than that would take to the woods with our rimfires knowing that we probably wouldn't get the limit of 8, at that time, but the ones we did take would give memories that would last a lifetime.
The rimfire group all hunted with super accurate 22 lr rifles. We had all saved our money and built our rifles from the ground up and we were all pretty competent at shooting small targets at distance.
All of us returned that morning with at least a few squirrels that all displayed one neat hole punch to dispatch in order to bring them to the dinner table that night.
Why did we use 22 lr instead of a faster rimfire cartridge ?
In the 1970's the only other rimfire cartridge that was popular enough to be sold in our local sporting goods stores was the 22 WMR. They had the same bullets we were shooting from our 22 lr's but were traveling about 1800 fps, almost twice as fast.
They had a much flatter trajectory and were more accurate than most factory 22 lr ammo you could buy back then. The only problem with this round for squirrel hunting was the speed of the bullet could do quite a bit of damage to the meat. Don't forget, we were hunting these things to eat.
My dad's rule was "if you were going to use a 22 WMR on squirrels, they must all be head shots. Losing half of the meat from a squirrel due to where it was shot was a taboo act in my family.
What is the best caliber for squirrel hunting?
Quick answer: If you are hunting squirrels for meat the 22 lr is the perfect caliber. If you plan to use a faster rimfire cartridge such as the 17 HMR, 17 HM2, or the 22 WMR you should plan on head shots only as much of the edible portions of the squirrel will be destroyed with body shots.
Here is a ballistic chart that compares a few rimfire cartridges ballistics.
The top table is a comparison of bullet velocity. You can see that at all ranges out to 100 yards the 17 caliber bullet is approaching twice the velocity of the 22. Because of the speed, even though the 17 caliber bullets are lighter, they are also delivering twice the energy at impact which is shown in the bottom table which is comparing energy.
Combine higher velocity with higher energy, typically due to mass but not in this case, and you get a projectile which is going to do more damage on impact. Especially with a bullet that is designed to expand on impact such as a hollow point or a soft tip variety.
To further communicate the effect of a 17 HMR on a target check out the video below from Desert Derpers. It's a good visual example of the difference.
As you can see at 100 yards or less, probably a little further, the 17 HMR is much more devastating than the 22 lr. This is great if your targets are varmints and you don't plan to eat your harvest but just reduce their numbers, but in a hunting situation this rifle can destroy a squirrel.
The 22 WMR is almost just as destructive as the 17 HMR, again simply because of the velocity and mass. In my opinion and experience, both of these cartridges are overkill for squirrels. The best rifle cartridge for squirrels is the good old 22 lr.
Is there a situation when a 17 HMR would work?
If you are going to hunt squirrels and a 17 HMR is all you have, there are some things you can do to minimize damage to your harvest.
The first is to take only head shots. In a hunting situation, this is much easier said than done. To make a good head shot at even 25 yards, your scope must be zeroed dead on, and you must have a very steady rest. This steady rest is not always readily available when you need it. Patience is required and don't expect to get the limit.
Secondly, use a FMJ or non expanding bullet. You will still see much more damage than from the 22 lr simply due to the higher velocity but it won't be as bad as if you used a hollow point.
The 17 HMR is a great cartridge for dispensing of small varmints when harvest damage is not a concern. It is faster and has a not your best choice for hunting squirrels that you plan to end up on the dinner table.