WIDE-BORE GAUGE PORT for BENJAMIN DISCOVERY & MAXIMUS

Description

This listing complies with eBay's air gun guidelines found here and I will only sell and ship air guns to buyers in jurisdictions where permitted by applicable laws - http://pages.ebay.com/help/policies/firearms-weapons-knives.html
This wide-bore gauge port has a much larger air passage than the Discovery and Maximus ports do. It produces more power for those models (chrony test results further down this page) and takes up less space in the tube allowing more room for air. It's made of brass with black oxide coating for extra corrosion resistance. It includes the 2 o-rings shown plus 4 extras. The o-rings are thicker than the ones on Discovery gauge ports, the same thickness as Maximus models. They are 3/32 cross-section (CS) compared to 1/16 CS for Discovery. To make installation easier they are a slightly smaller outside diameter and the o-ring channels are deeper so they fit both Discovery and Maximus tubes perfectly. The difference in inside diameter compared to the Discovery and Maximus gauge ports is compared in the last photo. The pressure gauge can thread in directly if a low profile is desired. We have extensions listed separately to space the gauge to fit with Discovery and Maximus stocks.
This port does not seal against the extension with an o-ring like the original Discovery and Maximus extensions do, thread sealing tape or high-pressure sealant should be used. We
suggest the military-spec thread sealing tape we have listed.
The port threads are
1/8 NPT tapered and do not fit the original Discovery and Maximus gauge extension threads which are 1/8 NPT straight. The high-strength stainless steel extensions we have listed are tapered to fit. Our upgrade 4000 PSI gauges are also a perfect fit and much better quality than the Crosman / Benjamin or paintball gauges.
The following videos cover the Discovery model which is very similar to the Maximus. The same tools, materials and procedures apply for disassembly, rebuild and installation of our custom trigger kits and complete trigger groups. eBay doesn't allow links to be active so you need to copy the red link and paste it into the address bar above in your browser.
DISCOVERY DISASSEMBLY :
https://youtu.be/woiQMwBbVxs
DISCOVERY REBUILD ( also covers some custom parts) :
https://youtu.be/TqDrNnTGPY8
CUSTOM RIFLE TRIGGER & CASING :
https://youtu.be/uRCkcXnTKsE
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. Staying at about a 100 FPS spread, 3200 PSI produced 11 shots more and a 100+ FPS higher peak with every shot above the peak at 2000 PSI.
Unmodified Discovery .22 starting at 2000 PSI :
1)      888.1   muzzle velocity in FPS (feet per second)
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
.22 Discovery with custom valve screws, Magnum Adjuster, wide-bore gauge port, 26" Maximus barrel and a starting pressure of 3200 PSI. The result was a lot more power for a longer and better-balanced shot string :
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
24)   949.4
25)   938.3
26)   918.7
27)   907.6
100+ FPS below peak power
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 shorter version and wide-bore gauge port. Both version produce the same power levels. The adjuster was set  3.5 turns back from full spring compression to produce a slightly longer shot string at lower power. The starting pressure was 3200 PSI. JSB Jumbo Monster 25.39 and Jumbo Beast 33.95 produced the best consistency and groupings of about a dozen types and weights tested. Heavy pellets work best at these power levels :
1)    817  FPS    33.95 g    50  FPE
2)    833
3)    837
4)    843
5)    845
6)    850
7)    853                             54  FPE
8)    849
9)    838
10)  824
11)  816                            50   FPE