If your marker won't work with HP, you can try the mini reg mod:
originally posted by Ken Crane at
www.angel-owners.com
If you have a high pressure tank you can modify the mini reg to lower the spring stack pressure so you may adjust the gun below 300 fps.
1) Remove all pressure to the gun.
2) Remove the mini reg from the gun by unscrewing it counter clockwise
3) Look into the top of the mini reg and locate the circle 'c clip'
4) With a circlip pliers remove the circlip
5)Carefuly turn the mini reg over and tap it on a padded surface
6) You will note that there are cuped washers stacked on top of each other they look like this: ((()))((())) (not in this order)
7)Remove 1 of the cuped washers (springs) from the mini reg stack
8) Reassemble in reverse order and re chrony.