Biohazard Modified Valve for the 2540
|The DAQ .25 / Biohazard 2540 Conversion
A while back I noticed a post on the Crosman Forum by Duane Wight (AKA Biohazard) regarding a valve he was developing. This design went beyond the many modifications he shared with the forum members, in increasing the volume of gas that could be cycled on each shot. After a couple of emails back and forth Duane offered to send me a prototype to use in a 2550 I was building up. While waiting on the prototype to be shipped, I happened to be talking on the phone with Dennis Quackenbush about a .308 Exile carbine he was making for me (great gun by a great gunsmith by the way). Dennis mentioned that he was considering having his apprentice make a batch of the Biohazard valves if Duane would allow it. I emailed Duane and told him about that discussion, and he followed up with Dennis, they worked out an arrangement, and a couple months later I was holding a completed valve!
The first thing one notes is that the valve is huge when compared to the standard 2240 valve, more than doubling the physical dimensions. As a matter of fact, the valve will not fit into the standard 2240 reservoir tube and requires a 2250 tube be used. Installation of the Biohazard valve is simplicity itself, made easier yet by the clear and concise instructions Duane sends with the valve. Just disassemble the gun, swap the tubes, insert the new valve, replace the hammer spring, and reassemble. When replacing the receiver Duane supplies various lengths of tubing to find the perfect fit for the transfer port. The entire process took less than an hour, and on completion I cocked the gun and dropped in a CO2 cartridge, tightened on the end cap, and squeezed the trigger ?? nothing happened! Removing the cartridge I noted that the piercing pin had not pierced the seal. Figuring that the cap didn?t push the cartridge far enough, I placed a penny behind the cart before screwing the cap back on. Voila! It did the trick!
Mounting the optics and heading down to my range, I tucked into re-zeroing the scope I?d removed when disassembling the gun to install the valve. On the first shot, the gun cracked and the pellet slammed into the target, printing dead on target! How bloody lucky is that, the scope went back on holding zero, allowing me to go straight back to shooting. I shot a string of eight shots, with the ninth demonstrating a significant drop in the point of impact with a concurrent drop in the loudness.
After tweaking the springs and getting the tubing on the transfer port worked out, the gun fires the 21 grain Field and Trophy pellets at around 520 fps. I've been fooling around with these valves for awhile now, and nothing I've done comes close to what the Biohazard valve does performance wise. I have to say that in my oppinion the only way to realize the full potential of the DAQ .25 kit is when it is coupled with the Biohazard valve. The one problem I encountered was getting the hammer spring just right, but that was minor. The only real problem is ..... Duane just can't make enough of these valves to meet the demand.
|This valve is bloody huge!!! The only way to get a fit is to use a 2250 reservoir tube.|
|The parts required for the modification include the valve and a 2250 reservoir tube (above)
I put eight pellets into a fairly small cluster with the last two exhibiting a little verticle stringing. But the bunny is down any way you look at it! (right)
|Duane sends out very clear and concise instructions that even a neophyte (or me) can manage.|
|The completed gun!|