I got to play with a CZ 452 American in .17 HMR a while back. It had a tuned trigger and Leupold 4.5-14X Vari-X III AO scope, but no bedding job or other tuning. With the Hornady 17 gr. V-Max bullet, in calm conditions, it averaged 0.715" for 5, 5-shot groups at 100 yards. Of interest, the rifle WOULD NOT shoot any of the other bullet designs (Speer TNT, Game Point, etc.) well -- only the V-Max or Winchester's equivalent. I've had several HMR shooters and a couple of gun store clerks tell me that their rifles/most rifles seem to strongly prefer the V-Max bullets.
It is insanely flat shooting. When zeroed at 100 yards, these trajectory results were obtained through actual firing:
12 yards (Yes, I have shot squirrels this close on occasion!): -0.96" low
25 yards - 0.53" low
50 yards +0.1" high
65 yards +.39" high
85 yards +.31" high
100 yards - zeroed
125 yards -1.27"
150 yards -2.32"
175 yards -4.77"
200 yards -7.96"
The little bullets seem to run out of steam pretty quickly after about 125 yards and are wind-sensitive, but capable of very fine accuracy. For smaller, lighter varmints, they work very well. On groundhogs, I'd rather have a .22 WMR. Up close, the .17 is VERY explosive. Example: Shooting a water-filled "Red Bull" 8-oz. can at 50 yards -- this is very soft aluminum and only about 2.5" in diameter. The top half was blown skyward and when the bottom half was examined, there was a sizeable chunk of jacket lying in the bottom of it... it had already started disintegrating! I saw a squirrel hit in the chest with one at about 30 yards, and it made a serious mess. Head shots are MANDATORY if you don't want a field-dressing/skinning nightmare on small game at woods ranges. Luckily, in a good rifle, it gives you the accuracy/trajectory to consistently make head shots as far out as you're likely to shoot.
Also, these bullets are not nearly so prone to riccochet as .22LR or WMR's. I did a test where I put a piece of white poster paper behind a still-green tree branch at 100 yds, and fired several shots from the bench, just barely glancing off the branch, and the bullets exploded from even the slightest touch. Thus, anything they hit in the woods is likely to eliminate the possibility of a bullet carrying any distance. The rifle/ammo were so accurate that it was no trick to just skim the bark of the branch or barely hit the branch itself, only 1/4" into the wood. I then did the same test using a flat rock to check for riccochets and got the same results.
Finally, as I started the last day of testing, I needed to foul the bore after cleaning, so I just fired a shot into a blank part of the target at 100 yards. I then aimed at the .17 cal. bullet hole, which was smaller than the intersection of my crosshairs. My next shot missed the first hole by only 0.1"!
Basically, you have top grade Anschutz .22 match rifle accuracy (think $1500 worth,minimum) in a $400 rifle, shooting over-the-counter ammo that, at $11.99/50 gives the accuracy the best Eley Tenex ($18.00/box) can provide at 100 yards, but with a relatively laser-flat trajectory and explosive killing power. If one did not want to take longer shots, the rifle could be zeroed at a shorter range than 100 yards and have a still-flatter trajectory, but basically, this setup gives the ability to hold virtually dead on out to 100 yards and hit with match rifle precision.
By comparison, an Anschutz match rifle using Eley Tenex standard velocity match ammo with a 50 yard zero dropped over 6" at 100 yards... which means you really need to be on your game at range/holdover if you want to use that rifle/ammo much past about 60 yards...
Hope this helps!
John