Yes it will sting or possibly injure the animal. Even though it's a relatively slow firing pistol. 200 FPS. The pellet will sting if fired a a close range. If you hit a rodent or very small animal it will penetrate the body.
Crosman does not own Marksman. Crosman made a Repeatairmodel and Marksman made a Repeater model. See the link below for the Marksman Repeater owners manual.
There is No C02 cartridge in the Marksman Repeater, it is spring operated
The Marksman repeater is rated at 200 FPS.
The Marksman 2002 Repeater is rated at 250 FPS.
There have been several models of the marksman repeater. The first one was made in 1955
18 BB according to Marksman
See the Link below for the "you tube" video for Marksman
It is rated at 200 FPS
100
Needs to be serviced/repaired
No way to do it.
See the link below