Whats the best caliber of rifle for varmits?

For accuracy out to 400-500 yards, availabilty and cost of ammo, it's hard to beat the .223

 

I would look at a 22-250 or 243. 25-06 is another good choice, but would definitely have to be a reloader as ammo is harder to come by.
Still alot of other factors that come into play though, as RC eluded to.
What range are you anticipating and how much shooting do you plan on?
If you plan on alot of shooting, then go with a caliber that is readily available if you don't handload.

 

I agree with the worm but .223 is hard to beat for cost even reloading.

 

Groundhogs are not a big problem in my area. We have a few and they are fairly easy to kill. I use a Hi Point 9mm carbine on coyotes. Shooting coyotes in this are is a close range affair. I just ride along the edges of field that coyotes frequent in a pick up truck. Once we spot the coyotes it's on. After a few coyote casualties they usually move on.

 

.223 is my vote, hard to beat for cost and accuracy not to mention a good match ballistically for most small to medium game.

 

.223, nothing more is needed for that type of shooting.

 

Get a 6.8 AR; you'll end up having that gun with you wherever you go.

 

I rarely shoot more than 100yds at varmints (armadillo, coon, possum, groundhog, etc.), so a .22mag does the job for me. I like the Hornady .22mag Vmax (ballistic tip) in my old Win 9422M, and the ammo is cheap. Longer ranges I agree with the .223 comments.

 

.223, .270 and .308. I been shooting rabbits with my .308. I had probaly tooken about 11 of them with my .308 since I got my .308 2 months ago.

 

I don't know how much punch a .223 will have at 500 yds on a coyote, but I know my 22-250 has done a nice job at that range on a lot of rockchucks. They would probably mass out about the same as the western coyotes I've seen. In the east the 'yotes run considerably larger.

 

The federal site lists a 60 grain nosler bullet with 250 foot pounds energy , a 42 inch 10 mph crosswind drift and a 13 inch drop with a 100 yard zero.
This would be outside of my capabilities to hit the vitals (5 inch) on a STANDING coyote.
It is commonly considered that a minimum of 700 foot pounds is necessary to bring down a deer and that is reached around 150 yards.
If you are shooting coyotes I would think you would be OK out to 300 yards IF YOU CAN PLACE A SHOT CONSISTANTY IN A 5 INCH CIRCLE. That includes accurate range estimation and wind doping. Range shooting is one thing and field hunting is another.
The above basics will be necessary for any caliber.
I think the 223 is fine for deer out to 150 yards with partition bullets and further on coyotes if one's marksmanship is adequate.
Some how I wonder how the military figures a 5.56 mm can regularly kill a man out to 400 yards with approximately 400 foot pounds-- the military 5.56 undoubtedly is loaded hotter but the example still stands ( I believe that is the Marine qualification distance)
For long distance shooting a larger caliber will buck the wind better 243, 6.5 ...
Just some thoughts from this quarter

 

Nope. Here's the USMC firearms qual. MARINE CORPS ORDER 3574.2K (2007) http://community.marines.mil/news/publications/Documents/MCO 3574.2K.pdf. Still 200, 300 and 500 meters (yds when I served), in various positions.

Btw, the above is a pretty good drill for those wishing to hone their rifle and pistol skills.

 

I use .204 for yote here in Maine the longest shot so far was just under 450 yards and took the yote NP. I have practice with it out to 600 as long as my aim is true they rarely run more then 20 yards if that...