Realistic pigeon killing distance

Only you can determine your maximum killing distances. You have already proved it isn’t 100yrds. Baby steps. Establish that you are deadly at 70-80yrds. Get comfortable with how your projectile reacts under various conditions at closer ranges before you start getting to distances that require even more skill to compensate and tune for. A gun that has a tune that can get you by at 70 or 80 yards might suck when you get to 100 and beyond. No quick answers and no shortcuts.
 
From my experience it’s all about shot placement. I’ve shot pigeons with 22 , 25 and 30 cal and I’ve had pigeons fly off after what appeared to be pretty hard hits. Of course how can you really tell. Lots of feathers flying and that “ pop “ sound.
I hate crippling any animal but it happens. I try to hit them at the neck body junction and I don’t shoot much over 80 yards. Only because any little wind will affect your shot placement.
The area I’m aiming at is about an inch in diameter and I have some top end equipment.
Shooting groups and hunting while having some similarities there is one big difference. You don’t get do overs while hunting. So you decide I’m skeptical about some of those long shots with air rifles. Skeptical not that is possible just as to whether it’s a reliable way to consistently make clean kills . I know there are guys that say they can reliably take ground hogs out to and beyond 100 yards. I limit my GH shots to 50 You very much have to know you own abilities 

 
We have all seem video’s of pigeons taken at extreme distances. And I would never suggest that there aren’t some guys that can do it . BUT I’ve never seen groups shot at those distances either.
I know my abilities and I know that at my age they are diminishing 

I’ve been around shooting a long time and I’ve seen some amazing shots.
I talked recently to a world class bench test shooter and I ask him what his best group was. He told me he once shot 5 shots under an inch at 800 yards. I believe him. WHY because others have testified that that if any one could do it he could AND his equipment. His front rest alone was worth twice my rifle and scope combined. His bench rest stock was made from beautiful birds eye maple. HE MADE THE STOCK. He made is fortune building antique reproduction furniture. Get the picture. 
My point there are guys that can but the vast majority can’t. If you are shooting pigeons beyond 100 an occasional sub 1 inch group isn’t good enough FOR ME 
 
Some very good points being made here. I can tell you as an Impact owner myself that right now my Impact is a solid 75yrd shooter. That’s with hundreds of slugs and some tricks of the trade applied. Can I print some nice 100yrd groups? Yes but don’t miss the key word I used. Some. I can hit things out to 150 but the keyword there is hit. Like Bubblerboy said, tight consistent groups every day all the time are required not only for a kill shot but also to be able to make accurate adjustments for wind and elevation. Or, like the video guys, you can have your gun just accurate enough to get in the vicinity of a far away animal and pray to get lucky. Then claim it was skill.
 
Usually when people talk about ethical kills the measuring units are FPE or amount of energy ethically killing a specified game. Check chairgun or strelok, you need 2 FPE for an ethics kill on a pigeon so 4 FPE to be sure? 

with that if you shoot FX hybrid 22 grain slug at 900fps you will be able to easily kill a pigeon with 4FPE at 730 yards. 

if you shoot a Jsb nock out 24.5 grain slug at 900fps you will be able to easily kill a pigeon with 4FPE at 800 yards. hitting something that far is a different story. 



To sum it up these things especially with slugs aren’t toys, they have far more power than a lot of people realize so be really careful please. 
 
I have a Taipan Veteran long in 22cal with power plenum and Huma Regulator. It is set at 900fps with JSB knockouts 25.39's. 

So it has 32.7 foot pounds at 100, which will go straight through one side of the pigeon and right out the other side. 

My JSB 22cal 25.39's are set at 23.4 foot pounds which should also go straight through the Pigoen. 

You could drop them at 200 yards with 24.5 foot pounds if you can compensate 80 inch drop. 

You should have more power than I do with the longer barrel.