I bought an oldmillitary 7mm mauser and it has a some rust on it so i was wandering if its possible to take the rust off?

Why coitinley! The method to use depends on where the rust is. If it is on parts that have non-critical dimensions, such as the butt plate, you can polish it off withemery cloth. I have shined up many a Mauser butt plate this way. However, if it is on the barrel or bolt, etc., you may want to use something less drastic, like a pad of 000 steel wool, or perhaps a piece of crocus cloth.

If you use steel wool, use some good solvent alongwith the elbow grease. Something like Shooters' Choice is good for assisting in removing rust.

If the bolt, lugs, and bore are rust-free, your problems are more cosmetic than physical. Eldeguello gave good advice. A little common sense, steel wool and/or fine emery cloth should do the trick combined with a good solvent. Even a little surface rust on the bolt body is no great cause for alarm. Work carefully and slowly, and you should have good results.

Be careful with emory cloth unless planning to reblue .Fine steel wool is good advise, you can rub quite awhile before removing much bluing. Just keep it wet with oil. I used regular ol detergent motor oil with good results.