If using a Discovery valve you must use a Discovery, Crosman Custom Shop or aftermarket breech that utilizes the further-back inner screw location under the bolt. A standard Crosman steel or plastic breech has the inner screw in front of the bolt, the Discovery valve blocks that hole in the tube.
All tubes listed in this section have an anchor-screw hole for the Magnum Tank Adapter. None of these tubes can be used without the adapter.
The 2240 tube is 8-3/8" long. The 2250 tube is 10" long. Both fit Discovery valves but require the small PCP pistol valve-screws I have listed instead of the Discovery version. The Discovery screw heads are too tall to allow a pistol trigger group to be used.
The 10" Discovery & Maximus tubes have the original holes and slots. They were cut to length then the front of the tube was custom threaded. They have the original pressure gauge hole in the bottom.
The 15.5" Discovery tubes have custom machined holes and slots you can see in the fifth photo. They do not have a gauge hole in the bottom.
The Magnum Tank Adapter mounts tanks up to 4.5" OD. This is the strongest, safest tank block design in the industry. It threads directly into 7/8" OD tubes including 2240, 2250, 2260, 2300, 2400, Discovery, Challenger, Maximus, 1701P, 1720T and Marauder Pistol. A 1" diameter shroud or muzzle brake has about 1/8" clearance with a 4.5" OD tank. The carbine in the photos has a 24" barrel and 10" 2400KT tube. The pistol is a 2240 with a 14.6" barrel and 2" OD tank. The anchor-screw and seals are included with an extra screw, Torx bit and extra seals.
The adapter has an anchor screw on the left side to lock it in a fixed position. The screw is T10 drive with a head diameter of .271". The hole should be .275" - .281" (9/32) to fit in a recessed fashion like valve screws do.
MARKING THE HOLE LOCATION: If you intend to mount the tank adapter to a standard tube you need to drill the anchor-screw hole. Thread the adapter all the way in. Back it out until it points straight down. Mark the center of the hole 1" from the back of the block. Deburring the inner edge of the hole after drilling helps avoid damage to the o-ring during installation. You may have to push the o-ring under the edge of the hole with a small slotted screwdriver to help it go past without being cut.
PRESSURE LIMITS: The adapter can handle pressure far beyond the limit of your gun. The limit your gun can handle depends on how many valve screws you have and how strong they are. With three of the custom valve screws I have listed, 3200 PSI is the maximum safe operating pressure. Maximus models with two custom screws can use up to 2400 PSI. For CO2 models you need to convert your valve to bulk-fill / HPA with a custom short valve cap, discovery valve stem and custom valve screw for 22XX. That is safe for CO2. It's also safe for HPA tanks regulated up to 1400 PSI if you use a 1.8K burst disc on the regulator.