Low power tuning for Avenge-X

I'm looking for some help with low power tuning on a .22 cal Avenge-X for indoor pest control in warehouse/equipment storage buildings with varying interior materials. Here are some of my thoughts so far............14 gr wad cutter running around 500 fps yielding 6-8 FPE and then move up from there if needed. I would guess most shots would be from 5 to 15 yrds. How slow can you send these wad cutters and get them to group reliably at close distances? Is the Avenge-X capable of the task? How low FPS can you go with the regulator all the way down and the hammer spring backed out? Has anyone cut a few coils off the end of the hammer spring or tried other "unconventional" methods? Here is my equipment list so far:

Avenge-X Classic Synthetic Stock .22 cal
Vector Optics Orion Max 3-18x44 FFP 30mm scope
West Hunter WH202 adjustable scope mounts
GX Pump CS3-I Compressor