Sterling STP Information Sheet

14 May, 1999

This marker has been factory set to be used on Air (or Nitrogen, USA)

If you are using regulated air, set the output pressure of the regulator for 450 /500 psi.

If you are using CO2 then please observe the following: -

VAPOUR ONLY: -
Due to the nature of CO2 it is very difficult to achieve vapour throughout extreme temperature conditions.
So if you choose vapour CO2 as your power source, then here are some possible combinations.

1. REGULATED. You will need a reliable regulator that allows CO2 vapour use. In addition you will need a bottle that has an anti-siphon tube fitted, this will help prevent liquid CO2 from being drawn into the regulator.

2. EXPANSION TANK. This would normally be used on a vapour set up in place of the regulator. However due to the nature of a pump this may be difficult to fit. Again an anti siphon tube will need to be fitted to the bottle.

3. REMOTE SET UP. This configuration will allow gas vapour to be drawn from the top of the bottle. Used in conjunction with a remote expansion system should ensure that no liquid will be drawn into the gun. Note, NO anti siphon tube is required on the bottles.

LIQUID ONLY:-
This set up is equally acceptable. You will need to fit a siphon tube to the bottles used with this set up.

Velocity Adjustment:-
Velocity adjustments determined by the differential spring tension on relevant hammer and exhaust valve. To simplify, the spring tension behind the hammer striking the exhaust valve and opening the valve, allows a gas burst to blow the ball out through the barrel. So, more spring tension behind the hammer will give bigger burst and therefore higher velocity. By changing this spring with one of less tension it will lower the velocity.

In the past days of the sterling, it was quite a common practice to "clip" a coil off of the spring to shorten it, thus creating less tension. Also, shim washers were used and placed in the hammer to "pack out" the spring creating more tension. The idea being to use a spring which allowed a range of adjustment, simply by adding or removing washers. A selection of springs will be available shortly in a spring kit from Arrow Precision.