any proven scopes for a nitro trail

My proven air rifle rated scope for my NP rifles is the Nikon EFR. NP rifles are 10 - 40 yard shooters in my opinion (and 40 can be a realistic stretch of "consistent" accuracy) without doing some mods to these rifles.

There are other scopes offered that will likely work well with a NP gun,, Hawke Airmax AMX as mentioned above, though a 2-7 or 3-9 would be my "go to" for 10 - 40 yds.(would love to see a 4x Airmax introduced) I believe reticle matters more than power(s) for these rifles and accurate range of shooting, the EFR dot / duplex works well without need of a ranging reticle, slight hold-over, hold-under usually puts the pellet where needed.

It's too bad Nikon chose to stop making riflescopes, they had a winner with the EFR for airgunners and rimfire shooters.😒
 
I have a UTG Hunter 3X9 non-illuminated on my Gamo Mach1 with nearly 20,000 shots on the scope and no problems except the common low budget issue of the fast focus eye piece moving and changing poi which is easily fixed with a few wraps of elec tape or an oring.
1582816400_9733239005e57dc906fd3c2.36178826_DSCN1785.JPG
These can be had for about $80 if you check around and are lighter than the illuminated model. UTG would replace it if I wish but the thing tracks, repeats and holds zero perfectly. One thing of note. I have two of them and they both have the same issue. I put new scopes through some pretty rigid tests before mounting and found that while poi doesn't change at different powers of magnification if always lowered to the power there is a ever so slight elevation change when changing direction of the power ring. So if you get one of these I recommend always moving to the power of choice from the same direction. I chose to always move down so the max power I can use is slightly less than 9. 
 
I have a UTG Hunter 3X9 non-illuminated on my Gamo Mach1 with nearly 20,000 shots on the scope and no problems except the common low budget issue of the fast focus eye piece moving and changing poi which is easily fixed with a few wraps of elec tape or an oring.
1582816400_9733239005e57dc906fd3c2.36178826_DSCN1785.JPG
These can be had for about $80 if you check around and are lighter than the illuminated model. UTG would replace it if I wish but the thing tracks, repeats and holds zero perfectly. One thing of note. I have two of them and they both have the same issue. I put new scopes through some pretty rigid tests before mounting and found that while poi doesn't change at different powers of magnification if always lowered to the power there is a ever so slight elevation change when changing direction of the power ring. So if you get one of these I recommend always moving to the power of choice from the same direction. I chose to always move down so the max power I can use is slightly less than 9.

The new version of this UTG doesn't have objective focus capabilities. Not sure what distance it's set at from the factory.