I got a 14" barreled .50 and 16" barreled .25 Quackenbush pistol in an estate auction at great prices a few years ago, and believe they demonstrate some typical DAQ gun qualities. Among those are solid construction, good accuracy when you find the preferred ammo, and lack of a bell-curve power-band virtue of HIGH power priority from the maker.
My .50 pistol prefers .495" swaged balls and shoots them surprisingly well. At the factory power level the first shot (with 181 grain balls) was 675 FPS, but the second shot was about 450. Took me a few hours to tune it down to get more than one consistent shot by cutting the extremely heavy hammer-spring shorter and adjusting the power adjuster (hammer-spring preload adjuster). But after cutting over 1.5" length off the hammer-spring I got her shooting two consistent shots at 580 FPS, the third shot down to 475.
I then started serious accuracy testing and found the thing shot well enough to keep moving the target farther, even beyond the abilities of the 2.5X pistol scope to draw a fine bead on small aiming spots. So I mounted a Crosman shoulder stock and 3.9X rifle scope, and kept increasing the range all the way to 50 yards. Then shot 5 consecutive two-shot groups that averaged 1.10" c-t-c, all five groups (ten shots total) going into 2.5" at 50 yards. Having found her abilities and proper ammo, I made her back into a pistol
Hope to hunt hogs with it some day; but per my usual hunting approach with airguns, will rely on brain shots.
Since pistols don't have 16" barrels, I had Steve Corcoran build a gorgeous carbine stock for the .25 caliber 'pistol'. The carbine shot 25.4 grain JSBs and 21 grain H&N Baracudas well, both at about 40 foot-pounds. As taken from my fourth book,
Airgun Chronicles- Thirty Years Of Airgun Testing And Competition-
25.4gr JSB Exact King, 3000 PSI, 14 shot p-band Low=823, Hi=850, ES=27, SD=11, Avg=835 FPS / 39.3 FP
30.2gr H & N Baracuda, 3000 PSI, 12 shot p-band Low=790, Hi=822, ES=32, SD=11, Avg=807 FPS / 43.7 FP
After overhaul & de-tuning, ‘Mini Mite’ consistently averages 1” five-shot groups at 50 yards.