I've been thinking of buying a RWS M34, but the other day I saw an RWS Mod 45 .177 with a Tasco scope for 150.00 at a local gun dealer. It looks like it has some age on it. Anything special to look for when buying a used air rifle? Is there a date stamped on it somewhere? And is this gun rated as powerful as the newer RWS's? I'm new to airguns, have plenty of firearms but am looking for something to plink with at home without annoying the neighbors, plus need to rid the area of squirrels and possibly some feral pigeons. Probably my answers are on this forum somewhere I'm still reading and learning. Thanks in advance for the help.

is usually on the tube at the rear on the left side of the gun, very small. Spring guns can be damaged (dry firing, leaving them cocked) so there is a risk.
If you cannot shoot the gun over a chronograph it would be hard to be certain.
A 45 (in good order) will perform like a 34.

There have actually been two completely different modern Dianas known as the model 45.

The first was introduced in the late 1970's, as a more powerful successor to the long-popular model 35. It was made about 1977 to 1984 or so, and is characterized by a large sliding safety at the rear of the receiver, and a bolt through the stock just above the trigger. This gun is rather large and mechanically complex, but is still well-liked and sought after.

This gun was so popular that soon after it was discontinued in the mid-80's, Diana created a new model 45. This is simply a model 34 action in a new ambidextrous stock that closely resembles the lines of the original gun.

Both are excellent, powerful and reliable rifles that should be fine for the jobs you describe.

Thanks for the info, I haven't been back by the gun shop. I do recall that when I looked at this 45 I noticed that the trigger guard was kind of square in shape. I assume this is the older model? I hear a lot of people saying that dry firing air rifles causes damage. What kind of damage and how hard is it to repair the damage?
I'm guessing the only real way to tell how good this gun is, is to bite the bullet (or pellet) and purchase it then try it out. No way to tell just by looking.

It probably was the older gun, which had an angular trigger guard. Again, the other main features are the big sliding safety and through-bolt above the trigger.

When a spring-piston gun is fired, the air compressed between the piston and pellet not only propels the pellet, but has the effect of braking the piston to a stop. Dry-firing lets the piston accelerate all the way into the front of the cylinder unchecked, and in theory can damage the piston, piston seal, and spring.

Most guns are engineered to withstand an occasional mishap, but habitual dry-firing will cause damage. Then again it's easy enough to replace damaged parts if needed.