what is considered long rang for air guns?

Depends upon the person and the air rifle.

I recently wondered, after seeing another Long Range Shooters of Utah YouTube video in which a guy even used a “pistol” to hit a milk jug at 1000 yards, what would be an equivalent range and size target for air rifle users. I don’t entirely approve of spotting for the shooter, or indeed helping a shooter in any way, such as LRSU do.

For approx 900fps rifle users, and given the skills and variables effecting such pellet drops, I think that 150 yards for a golf ball would be an equivalent test. However, in general, I think that beyond 100 yards has to be considered long range. Ted's videos of one hole groups at 100 yards may make some people think that such is easy, happens every day, that all you need to do is buy a Bobcat & other equip and that they will automatically become such a shooter and produce such groups everyday.....but the reality is usually different.
 
Cookie, I guess I missed that video, but I happen to agree with you. There are limits to airguns. And no matter what you see, you have to think, am I capable of repeating this? If your already a shooter, via paper or live targets. It's sure to help know what your guns capable of. And what your realistically capable of doing. But if I had to guess, I would need to know what make and model you got. As cookie said. Steve 
 
For me I look at long range as when you have to really pay attention to the impacting elements from the enviorment. 

When a group opens up above 10-15mm I would consider it long range with any airgun given you know your gear. 

With my Bobcat .25 i think 70 yards+ has to be considered long range for my personal abillity. 

When shooting my .177 AA springer i think 40+ is very challenging. 
Just my view on this top. 
Cheers
 
With the bobcat 30, 120 yards is a breeze with winds at moderate speeds. The gun is capable of much more but I haven't tried it at longer ranges. Effectively the .25 and .30 cal Airguns I guess should be effective till about 170 yards. My Hatsan AT 44 tactical in .177 has been stretched to 102 yards using JSB 10.34 grain pellets. With moderate winds I have hit a crow sized target 8-9 times out of 10 consistently. At high winds I have missed the target completely. This also has a lot to do with the power of the gun. I have a friend who has a modified condor which shoots .25 slugs at 85 fpe. The gun shoots super accurately till about 210 yards but you only get about 10 shots per fill. Coke bottle sized targets in high or low wind is easy given the power and weight of the slugs. Beyond that range I have never tried to stretch any airgun.