You didn't clarify, spring gun or PCP, I came in here under general air gunning so, if it was posted under one or the other, my bad.
It all depends on what's acceptable for your usages. If you're going to compete, or if you hope to hit birds, pests, tin cans. Or just trying your best at relaxing, breathing, and seeing what you & rifle can do.
I've seem amazing groups out of cheaper rifles, and OK groups out of rifles I expected better from for the price. You have to be the judge of your question unless you're asking if you should plan on attending a competition or something. Inquiring to see if maybe you think gun is at fault, haven't found the perfect brand to barrel match. Honestly I've bought rifles used that came with pellets. tried them, and saw why they were selling. Different pellets, redrawn or even a simple cleaning, maybe a scope wasn't holding zero. I've seen that a lot on spring guns. Guys give up because it wouldn't group. Once tuned and good mounts groups shrunk to 1/2 or more.
So, my main question would be did you mean a spring gun or a PCP. The 10 shot judgement is more what YOU can do instead of the rifle. Pellets are not bullets by Federal or handloads and consistency, flyers are easily explained.
In general though, for normal non comp guys, I agree with AirNgasman. 1", 3/4", 1/2" @ 50 as if my rifles are doing 1/2 @ 50, it's subMOA in no wind conditions or you happen to read wind like a magician. I just put 3 pellets touching in a cloverleaf at 58 yards with a .22 Discovery. Not regulated. JSB 18.1's If it can do better, I doubt I can off a rocking chair and with no pellet sizer, sorting, weighing, a regulator. You can get to one hole groups. It's how much do you wish to spend & practice. My .177's are for 50 yards and under mostly. I personally am happy if they can hit English Sparrows at that distance. If the wind is above 10mph, I'm not out there trying to compensate to pest. I do love to shoot in snow storms at far (up to 200 yards) just to learn the wind. it's nothing more than long range plinking.Sticking to your .177 question, I'll stretch them out to 150 yards in snow but 3.8ftlbs, again, plinking & reading wind for fun.