As long as the cylinder has a rating of at least 125psi maximum pressure, yours is rated for 250psi, and is not altered, with the exclusion of the removal of a mounting pin, then the cylinder is completely legal as of 2017.
R80. All pneumatic items must be COTS pneumatic devices rated by their manufacturers for burst or
maximum pressure of at least 125psi (~862 kPa).
Automation Direct also has competitively priced pneumatic cylinders. Bimba is also well priced off their web site. Both of whom are major sponsors of First. The market for round body air cylinders is pretty saturated and competitive. It is sort of a commodity item. Anyway the thing to do is read the current rules and make sure you have documentation showing your cylinders meet the specifications for game.
This is the big qualifying rule that’s needs to be satisfied for most pneumatic components. Must be rated for at least 125 psi. As long as the part is under the $400 budget limit, and attached using fittings and tubing that meets the rest of the rules, it would be allowed. It is helpful to print off pages like this that list the component’s rating, it can make going through inspection faster.
The specific pneumatic rules start at R79 (page 32) of this part of the manual: link
To add a little info here, some manufacturers are listing only “working pressure” specifications, while “max pressure” or “burst pressure” are much higher but are not printed in the specification sheet. The “working pressure” specification is where the other specifications are guaranteed to be met. In general (but not always), “max pressure” is often twice what the “working pressure” specification is. Please remember that some parts may be damaged by exceeding stated working pressure even if they do not exhibit a catastrophic failure.
Working pressure: pressure the component is designed to work
Proof pressure: maximum pressure before damage. Component may or not work at this pressure.
Burst pressure: Exceed this and you will be sad.