there are very few people who can group this good the size of a 10p peice at 60yds with a sub 12 air rifle.
I regularly practice 25mm KZ on a reducer resetter at 55 yds at the club range. I will nock down the mini bird probably 19 out of 20 and reset 9 times out of 10 when I do my bit and I am quite consistant.
This is very different from taking a shot in the field and whilst I would support your encouragement of pushing and testing your marksmanship, it is not proper to give the same advice on live quarry. your range is set by your ability to group not by your desire to push boundaries.
All I am saying is be realistic - field shooting is a very different thing to club practice where you can spend a lot of time getting your eye in and allowing for weather. In the field, its a one shot assessment and it isnt justifiable to take such a risk unless it is a british politician in which case it is fair game