Here's an item you may be missing on those newer vintage Spyder's. It will drop the bottom line ASA about 1/2" and push it forward about 2". It has inline attachment holes and has a built in milled dovetail rail for the newer Spyder dovetail mounted bottom line ASA's. No more uncomfortable off-balanced feeling all day like your arms are fully extended when using those larger HPA tanks. This little puppy will push that tank forward for a more natural feeling shooting stance.
This is a replacement for Kingman part #DRF011 in your manual but may be used on any marker with inline mounting holes and dovetail mounted ASA.