"I bought this exact package about four years ago and I thought I would just give some helpful notes:
1. It does not actually come with the rail mount in the front, so don't be fooled. I have not been able to find a place to buy it either, so keep in mind that a bipod for this gun is probably not going to happen.
2. YOU MUST USE .3g BBs OR HIGHER with this gun for accuracy. Once you get the .3s in, you will realize how truly accurate this gun is.
3. If you want to use .3s, the FPS will drop to about 450 or 480, the "510" is if you want the gun to be a .12g cannon
4. Obviously, you cannot use this gun without a scope. DO NOT put cheap scopes on this gun. buy one of the $40+ ACOGs or a legitimate airlift rifle scope. NOTE: Every time you take a scope off your gun after adjusting your sights, you have to readjust when putting it back on.
Overall: This is a great buy. Mine still works in perfect condition. Remember, spring rifles are always the best for long range and durability. Never store a spring gun loaded for long periods of time either, as the spring loses its tension."