Well, I have made significant advancements to the Kingslayer(MkII):
Note the expanded Hornet Tank. Waiting on the final seals to cure before testing, but it should be magical, as it's @ 10.5" of 1/2" pipe all told...

Also note the modified Cylinder Release Lever. This grip is so comfy, I
tell you. The ring is made from 2 Nightfinder priming handles sandwiched together with epoxy and attached to the previous "Little Brudda Eastah Basket" handle, which has also been epoxy reinforced.

For any wondering how much the lever needs to be moved to affect the locking cam?
This Much:

In other words: Not much at all. With the ring in place, the lever is much easier to action than before, and it's easy as pie to do with just my middle finger, while all my other fingers stay right where they belong*.
Of course, the standard release button is there, though the bottom of it has been removed so it doesn't interfere with the lever.
I'm somewhat tempted to run an aluminum Slurpee straw through the 1/2" pipe to use as a pinhole sight, but it would reduce the air capacity of the expansion by @40-50%, and the slight downward angle would be great for arcing fire, but not so much at medium-short ranges.
*In your girlfriend.