For elevation I use gear retract servos. Strong, and slow they allow for fine movement.

Freaky has a point. It takes a lot of effort sometimes to get a servo recoil in place, and when it fails it is a lot of work to get at it to replace it. Might be an idea to invest in a quality servo with metal gears for recoil. Run that barrel headlong into an unmovable object and the weakest like could break. On a low cost servo it migh be the tiny nylon gears.


Having said that I use cheap servos with tiny nylon gears for recoil, and have only had a couple of issues.