CUSTOM DISCOVERY VALVE SCREWS for 3000 PSI

$1.25

IF YOU NEED THE T25 TORX BIT SELECT IT FROM THE DROP-DOWN MENU AND ADD IT TO YOUR CART

PLEASE READ OUR TUBE DEFECTS PAGE BEFORE USING ANY OF OUR CUSTOM BULK-FILL, PCP OR HPA PARTS. THERE ARE RARE BUT IMPORTANT SAFETY ISSUES TO BE AWARE OF

THESE SCREWS ONLY FIT DISCOVERY MODELS. We have other custom valve screws listed for 2240, 2250, 2260, 2300 series, 2400KT, Maximus, Fortitude, Marauder Pistol, 1720T and 1701P.

These screws were designed by Magnum Airpower and custom manufactured, they are not available from any other source. They are direct-fit for Discovery models, no modifications are needed to use them. They safely raise the operating pressure to 3000 PSI. They are 410 stainless steel heat treated to meet metric class 12.9 with a specified hardness of HRc 39-43. The approximate tensile strength is 185,000 PSI. The head diameter is .3155", the head height is .0975" and the thread size is 8-32 x 3/16".

The third photo shows just one of these screws holding the valve with 3300 PSI in the tube. The pressure on the gauge is clearly visible in the photo. This is the strongest screw that exists for Discovery models. DO NOT PRESSURIZE A TUBE WITH ONLY ONE SCREW AS SHOWN IN THE PHOTOS, A LETHAL ACCIDENT COULD OCCUR. THIS DEMONSTRATION WAS DONE IN A CONTROLLED ENVIRONMENT WITH PREPARATIONS THAT MADE IT SAFE. ALL THREE SCREWS MUST BE USED TO HANDLE HIGHER PRESSURE SAFELY.

Contact us if you have any questions, making modifications to your airgun can be dangerous if not done correctly.

Empty all air or CO2 pressure from your airgun before installing these screws or a fatal injury could occur.

  Except for the original valve screws, the Discovery PCP tube assembly is as strong as the ones on similar Crosman/Benjamin 3000 PSI models like the Marauder Pistol and 1701P. All are made with the same 1020 DOM steel tubing. All of the other pressure containing components are as strong, the stainless steel Discovery fill adapter is actually stronger than the aluminum one on the PCP pistols. It's safe to use more pressure in the Discovery when the valve screws are correctly upgraded. We have destructively tested this screw design beyond the claims confirmed in the photos.

These screws fit our Magnum Valves perfectly. They fit factory Discovery valves a little on the tight side, the last 1/64 of an inch requires a little extra force to get the screw head snug against the valve. Do not over-tighten, they should be hand-tight using a driver handle. Using a wrench or ratchet can damage the threads in your valve. Standard Discovery valves are a relatively soft aluminum alloy so the valve threads will strip more easily than the threads on these screws. Our custom valves are machined from 7075-T aluminum which is as strong as many mild steel alloys, the holes don't strip easily with those.

The following chrony test results compare a standard Discovery .22 to one modified with our custom parts. 14.3 Grain pellets were used for both tests. Testing was stopped at 100 FPS below peak power. These first two tests demonstrate the benefits of using higher pressure, it produces a lot more power with less shot-to-shot variance for a much longer shot count.


Unmodified Discovery .22 starting at 2000 PSI with 14.3 grain pellets :

1)      888.1   Muzzle velocity in FPS.
2)      901.0   Peak power.
3)      899.8
4)      878.8
5)      877.7
6)      871.5
7)      855.6
8)      854.9
9)      849.6
10)    843.0
11)    837.1
12)    836.0
13)    827.6
14)    819..7
15)    813.4
16)    797.1   100+ FPS below peak power, very poorly-balanced shot string.

.22 Discovery with custom valve screws, Magnum Adjuster, wide-bore gauge port, 26" Maximus barrel and a starting pressure of 3200 PSI with 14.3 grain pellets : 

1)     958.8
2)     965.9
3)     971.2
4)     973.4
5)     977.2
6)     978.9
7)     984.5
8)     991.6
9)     994.7
10)   989.3
11)   997.6
12)   1000
13)   1007
14)   1002
15)   1005
16)   1009   Peak power.
17)   998.8
18)   1002
19)   990.1
20)   982.7
21)   977.8
22)   965.2
23)   958.3  A perfectly-balanced shot string would end at shot 23.
24)   949.4
25)   938.3


Same .22 Discovery with 26" barrel and Magnum Valve. It produced about 10 consistent shots starting at 3200 PSI with each pellet weight tested :

PSI     PELLET   FPS     FPE

3200   10.03 g    1288    36.9
3200   14.3 g      1142     41.4
3200   18.21 g    1086     47.7
3200   25.39 g    1000    56.3
3200   33.95 g     905     61.7


  The following chrony results were produced with the same gun described above but with our Magnum Bypass Valve instead of the wide-bore gauge port. The bypass valve and wide-bore gauge port produce the same FPE. The power adjuster was set  3.5 turns back from full spring compression with the bolt cocked to produce a slightly longer shot string at lower power. The starting pressure was 3200 PSI. JSB Jumbo Beast 33.95 grain pellets were used to produce maximum FPE and accuracy, heavy pellets work best at this power level with 25.39 grasin JSB being the lightest we generally use above 55 FPE:

1)    817  50  FPE
2)    833
3)    837
4)    843
5)    845
6)    850
7)    853   PEAK POWER 54 FPE
8)    849
9)    838
10)  824
11)  816  50   FPE