When selecting a deer hunting rifle what is the maximum groups you can have before ruling out that gun?
The answer is gonna depend highly upon:
-at what distances you'll be shooting (based on terrain, flora cover, etc.)
-whether or not you're disciplined enough to not take shots that are beyond your established range, based on the capabilities of your rifle and you
-How much you practice under field conditions / how good a shot you are under field conditions
-(closely related) whether your "field condition" is rested or unrested (e.g. tree stand with horizontal rest vs. walking/still hunting).
-Whether you're shooting vital shots or neck shots, as well as general size of the deer in your area (these determine target size)
-etc.
But, without knowing more, typical hunting situation, typical skill, ranges, etc., you figure....... take the vital zone (heart/lungs) of say, a typical sized deer - outside the deer is about a 10" circle (5" radius). Allow 4" for "field condition error", including shooter hold, shooter range mis-estimation, wind effects, and angle vis a vis horizon effects - i.e. 2" on either side. This means you need the rifle to hit within a 6" circle. That means you need a 12 MOA gun/ammo combo at 50 yards, a 6 MOA gun at 100 yards, 3 MOA at 200 yards, 2 MOA at 300 yards, and 1.5 MOA at 400 yards. 400 yards shots are pretty insane, and just ain't gonna happen realistically. At least not ethically, in 99.44% of situations. And since 300 yards shots are very rare, but not altogether inconceivable, you want a rifle that shoots roughly 2 MOA from a rested position at the range, or about 3 MOA if you limit your shots to 200 yards and are a *reasonably* steady/good shot.
Now, since (as Art & WBB & others have said), pretty much any modern turnbolt will shoot into 2 MOA with ammo it likes, you can pretty much grab ANY modern rifle made out there and with proper ammo testing, zeroing, and practicing under field conditions, the deer are as good as dead if they meet up with you. Just as true with a $244 Mossy 100 or $279 Stephens 200 or $195 NEF or $170 Rossi, as it is with a $1,250 Kimber, Sako, or whathaveyou, or anywhere in between.
That's actually an imprecise calculation because the 4" allowed for to provide for field conditions is actually gonna depend on the distance, and so this should be expressed in MOA, not inches, since any error is magnified the further out you go. So it's a decent analysis for 50 to 100 yards, but not real pretty after that. You need a progressively better and better gun (not to mention a better and better shooter), the farther the distance.
In other words, a 6MOA gun is probably fine for hunting if all shots are 100 or less (and heck, a 13 or 14 MOA gun is going to work if all shots are under 50 yards, instead of 12 MOA). But at 300 yards, you actually need a gun that shoots a tad BETTER than 2 MOA rested, even with better skill...shooter error, wind, and range misestimation are all magnified. So more like 1.5 - 1.75 MOA gun/ammo combo at 300 yards, and preferably a 0.5-.075 MOA gun/ammo combo if you're gonna try a 400 yard shot, and stay ethical.
All IMO, of course. But distance, distance, distance - it all depends on the distance!
Yes, and what Art says about a rifle's stock-to-body natural fit is right on.....
If the rifle puts the first two shots very close together, you're good to go
Yes, provided those two shots are close to the point of aim, not a foot from the crosshairs.