Air rilfes have been made that will take down large game.
If you are asking "WHAT" not "Where" is the most powerful under lever .177 air rifle. Then I suggest the "Hatsan Torpedo 150 air rifle." I comes in at around 1250 FPS where as most of the other under levers fire at around 950 to 1000 FPS. However Under levers are not the most powerful air rifles. The PCP (PreCharged Pneumatic) Class of air rifles are the most powerful air rifles. An "Air Force Condor and the Evanix Rainstorm" fires a .177 cal pellet at 1300 FPS.
you can't
Currently it's the Beeman RX-2 at 1125 FPS in a .177 pellet
Only if the scope is designed for air rifles. Regular firearm scopes are made different than air rifle scopes and many will break if used on an air rifle because the recoil is different than a firearm.
The most common target air rifle pellets are made of lead, although other materials such as tin, steel alloys or even plastic are used for pellets.
No
For a air soft BB gun it's okay not powerful. For a regular BB gun "NO" that is not powerful at all. A Daisy Red Ryder BB rifle will fire around 325 FPS most new pellet Air Rifles will fire at least 1,000 FPS. A really good Air soft rifle will get around 500 FPS.
Yes. Pump, Spring and PCP (PreCharged Pneumatic) are all more powerful than a C02 system
Whether or not an air rifle is more powerful than a cross bow depends on the air rifle or cross bow. Generally a hunter's cross bow is more powerful than a child's bb gun. However, during the Napoleonic Wars, the Austrians had an extremely powerful repeating air rifle. It could shoot several hundred meters. Austrian solders armed with them could shoot Napoleon's solders from such a great distance that Napoleon's solders could do nothing about it. Eventually they ran out of bullets.
Not designed for this type of modificaiton.
lets start with. Who made the rifle? there are over 100 different companies who have made air rifles.