Gauging distance with the Benjamin Trail NP .22

Hello all! So this weekend I finally had the opportunity, after many weekends of fine tuning my Benjamin Trail NP .22, to hunt. I've installed the GTX trigger and shot about 500 pellets through it. I bought 10 different types of pellets and the rifle preferred the JSB Diablo and the Gamo Match over all the rest. Because the JSB was heavier I decided that would be my hunting round. I sighted it in at 25 yards and was pretty dead on accurate. So, I went to my buddies horse farm in upstate new york to eradicate their pigeon problem. I've hunted there before with my Ruger 10/22 but the horses get scared and people get mad so no more of that. When I get there, I had a shot immediately on a fat male, but completely missed. I figured this was from excitement or something. But then I missed the next 20 or so shots I had on Juvenile Starlings and other pigeons. I couldn't figure out why I was continually missing. The only thing I could think of was that I was gauging the distance incorrectly. So I went home and I shot another 20 rounds through it at 25 yards and was dead on again. Anyone have any insight to this?
 
Since its a break barrel its going to have hold sensitivity. So when your at the bench your probably holding the gun the same every time but when you go off hand your going to be holding it differently more tightly ect. So when your at the bench sighting it in next time try to hold the gun in relation to how you would shooting off hand make sense? Also you said you traveled I don't know how far away but if that was a different climate that could also affect your POI so if you go again your probably going to want to shoot some groups at the place your hunting at.
 
The loopy trajectory of a pellet in comparison to say your 10/22 might be the problem? Pellets are highly affected by wind and pellets can drop alot in as little as 5 yards. Also, if you are shooting rested at home and we're shooting off handed or rested in a different manner when at the farm could also be causing issue as springers/np's tend to be rather hold sensative.

If you know your velocity or have a very close estimate, a ballistics program like chair gun or strelok can be a very useful tool. If you don't know your velocity, then try shooting targets in 5 yard increments and noting how much pellet drop you have. You can learn windage in the same manner.
 
I appreciate the quick responses. It's very frustrating watching these videos of people whacking bird after bird with perfect accuracy. I think I will sight it in to 40 yards with the same pellet and then do as you both said. Where I hunt is only a few miles from my home so there isn't a change in elevation but the wind there is different than where I live. They live in the valley so wind tends to tunnel through there. I always find a way to rest my rifle on something but I do hold the gun differently when in the field. It is spur of the moment shooting so there aren't any premeditated shooting platforms. 
 
Are you shooting on an incline at the pigeons? Watch teds last video if you are and then get some practice in at the angles you wo be shooting the pigeons at before you take to live animals again. If you're missing but the whole bird now, you're bound to get closer but not perfect until you've got the practice nailed. 

Only prrfect shot shot placement will result in big bags. 
 
When you say you missed, were you able to see the pellet to determine how far off you were? If the pellets were constantly dropping short or shooting high, but otherwise "on target" then I'd say you were misjudging the range. However, if the pellets were jumping all over the place then I'd agree with what's already been said with how you're holding it. Personally, I don't see the same hold problems with my NP2 that I saw when I shot my RWS 34 which I attribute to the Nitro Piston versus an actual spring, but I'd also say it is common for me to have one or two "flyers" every 10 shots or so.

If you weren't able to see where the pellets went, it will be almost impossible to say what really happened. It could have been the hold, body alignment, how the trigger was pulled, breathing during the shots, wrong distance, incline/decline angle adjustment, wind and probably a bunch of other stuff as well. I've flubbed shots that I considered give me shots because I didn't think the basics mattered as there was no way I could miss. Instead of focusing on the shot, I was thinking about the smiles and congratulations.

Another thing to look at is the pellets you're using and how you are seating them in the barrel. If you haven't tried a pellet pen yet I recommend getting one and giving it a shot (no pun intended). Not only will this help ensure the pellet is placed routinely in the barrel (which is very important), but it also helps prevent issues such as bent or pinched skirts.

I'd recommend you start by getting a range (whether it is with a range finder, tape, or whatever) and seeing what the distance actually is. If nothing else, this answers your actual question about your range estimation. Next, practice shooting from positions that you plan to shoot from. Third, have patience. It's been a hard lesson for me, but if you can calm yourself down and wait for the shot you'll be much more successful then trying to hurry it up. Remember, if you don't shoot you have a better chance of getting a shot then if you shoot and miss then have an educated and scared the bird.
 
If you sighted in at 25 yards then you have to holdunder or holdover at all other yardages except your second zero. I like to set my first zero at 15 yards and with the Nitro Piston your second zero should be around 35 yards then the pellet is dropping from that point on. You need a range finder to improve your accuracy and you need to map your gun in for the different yardages. Check out my NP2 accuracy video on youtube. You need to map your holdunder or holdover for the gun every 5 yards out to however far you want to shoot accurately and keep that handy for reference (I tape mine on the stock). It helps to have a scope with military dots for reference. I also suggest that you use some shooting sticks while practicing and hunting and make sure you rest the gun in the same spot each time for repeatable accuracy. You can find good range finders for around $100 nowadays. I really like the Primos Trigger Stick Jim Shockey Gen 2 tall Tri-Pod edition for the best accuracy while hunting. You can use it sitting or standing. Get your gun's yardages mapped in and you will be ready to drop them at all yardages.