100-350 USD
Start by getting an owner's manual from the manufacturer, read it, and follow the instructions for cleaning and lubrication.
no
Follow instructions in the owner's manual. Contact the maker if you don't have one. If not in business, take it to your local gun smith.
What model, what condition, what year is the gun? You need to supply this information to get an answer.
Yes.
9mm means the firearm shoots a bullet that is about 9 millimeters wide.
Hoppe's #9 and a tootbrush
You can from some, but they have to be designed to shoot both.
Shotgun by far
10-100 usd
AEK-999 (Machine gun - 7.62 x 54 mm) AO-9 (Machine Gun - 23 x 115 mm) AO-18 (Gatling Machine Gun - 30 mm) DP-27 / DP-28 (Light machine gun - 7.62x54mmR) * ** DPM (Light machine gun - 7.62x54 mmR) ** DA (Light machine gun - 7.62x54mmR) ** DT / DTM (Light machine gun - 7.62x54mmR) ** RP-46 (Light machine gun - 7.62x54mmR) * DShK ** DShK 1938 (Heavy machine gun - 12.7x107mm) ** DShK 1938/1946 / DShKM (Heavy Machine Gun - 12.7x107mm) Kord (Heavy Machine Gun - 12.7 x 107 mm) KPVT (Tank Heavy Machine Gun) Maxim M1910 (Medium machine gun - 7.62x54mmR) NSV (Heavy Machine Gun - 12.7x108mm) * PK (GPMG - 7.62 x 54 mm R) ** PKM (GPMG - 7.62 x 54 mm R) ** PKSMN (GPMG - 7.62 x 54 mm R) ** PKT (GPMG - 7.62 x 54 mm R) Pecheneg (Machine gun - 7.62 x 54 mm) SG-43 Gorunov (Medium machine gun - 7.62 x 54 mm R) TKB-523 (Light Machine Gun - 7.62 x 39 mm) 6P62 (Heavy Machine Gun - 12.7 x 107 mm)