is it the scope or the gun?

hey guys I was out breaking in my benjamin summit. Around shot 300 I was able to consistently hit a 12g co2 cartridge (spent) time and time again. By the time I put another 100 pellets through it she started shooting really high (several feet) I've been fiddling with it for hours now, elevation is bottomed out and it still shoots pretty high. I put on a different scope and same problem. Any ideas?
 
Two things come to mind. The scope mounts are sliding due to recoil or the stock screws that secure the action have worked loose. You need to check them regularly as they work loose on spring guns. That gun has a Picatinney rail correct? if so it shouldn't be sliding there but check all scope related fasteners. Also what distance are you shooting? Which pellets? The more info on your set up and technique the easier it will be to help you. Do you have access to a chronograph to help diagnose problems? They are very helpful for keeping air guns tuned and working well. Also you need to master the artillery hold, are you familiar with that? Learning hold a spring gun correctly can make all the difference in your shooting enjoyment. Good luck!
 
thanks for the input guys. Allow me to attempt to be more informative. Firstly, this is my first rifle without open sights and was taught the artillery hold at age 11 or 12. I was trying to do some final zeroing in of the scope as I figured it was pointless untill it was broke in. For this I was using a couple 50# bags of chicken feed as a bench rest in a kneeling/squatting position but I 'normally' shoot standing. Yes, the rifle has a picatinney rail. All scope mounting hardware was present and cranked down. I did check my stock screws when the issue first happened one was marginally loose so I cranked that down. The first indicator that I had a problem was a very very loud report on a shot after that the muzzel took up quite a bit of the sight picture when I couldn't see it at all before so I figured it was some last bit of dieseling and maybe I bumped the scope or something so I unmounted the scope and the rings, remounted them and tried to re zero at 20 and 50 yards with crossman .22 14.3g hollowpoints and had no luck. Even when I ended up with the elevation knob all the way down and windage all the way out, she was still shooting about 3 feet high and 9 inches left. SO I went and got a different scope I dont use from my other springer and tried that one. Similar issues but there was some improvement.
 
Little update: so after trying a few things with my rings like shimming em in different spots and just aiming SUPER low I decided to pick up the phone and call big 5 as the gun was only a week old and I truly dont believe I did anything outside of 'normal use' meaning no drops, no dry fires, no intentional desiling and no miss-loading the projectiles. I truly thought they would tell me to **** off but what I got was a very friendly manager who very politely told me he couldn't tell me much over the phone and to just bring the rifle in and at the very least they would do their best to help me fix my issue.
I've never walked into a store with a gun of any kind before; this made me nervous as I have a big blue mohawk and am covered in tats in an ultra conservative area...when I got to the store I warned the clerk what was about to happen and to please not call the cops (oh silly me) . She smiled and paged the manager. When he got there I told him what was up and he just said 'sounds broke to me. Let me get ya a new one."

And so I have a new one, the shroud actually comes off, it Zeroed in at 50 yards much faster and the first 50 shots were quieter than the first 200 out of the old one....guess I got a dud! thanks for yalls input though!
 
ill have some photos up in the next day or two. thursday and friday are my weekend :p Wanna hear some poop? my new, new rifle did the same friggin thing at around the same shot count! it really sucks because until they break, those rifles shoot straight and hit hard. I'm currently inclined to just get a refund and put the $$ twards something better. I'd love to try something tried and true by the community. Powerful and accurate springer is what im after. Budget is somewhat flexible. Any suggestions?