Hi Michael, the tube is the stock 2240 tube with just the threaded end cut off. That was to get back to the full tube thickness to support the QB79 tank block. So it is slightly shorter, but probably also looks short due to the long, slender Disco barrel. I will attempt to answer your question about the custom shop vs. from scratch approach but let me know if I go astray. Firstly, I will make the assumption that if you go with the custom shop, your long barrel options are limited to .22 cal. Whether that is a good choice depends on two key considerations, in my opinion. The first consideration has to do with your shot count and energy goals and typical shooting distances. Or if you are interested mostly in hunting, I would rephrase this question into what quarry and shooting distances? Depending on your goals, the choice of caliber may lead to some ripple effect considerations to the rest of the build. So I would want to know more about those things in order to know where to take the discussion. The second consideration is that Crosman's .22 barrels still seem to be more of a gamble than the .177 in terms of accuracy and being pellet fussy. Regarding the scratch approach, I don't know if the Challenger is a drop-in replacement but if it is, that should be a fine choice since it is a quality Lothar Walther barrel. A LW barrel is somewhat expensive compared to a Crosman barrel but this is one of those cases where it's easy to justify. What I mean is, it's peanuts compared to buying a LW blank, getting it machined, and then getting it blued. Here you get the benefit of Crosman's buying power. At the same time, I know you've written of being a student without a lot of disposable income so if you have more time than money, taking a .177 Disco barrel and investing a little sweat equity can produce very good results. Not everybody wants to be a gunsmith though. John, thank you, sir! I'll see about posting some pictures of targets this weekend.
Okay, I see what you mean. Yeah, that is definitely shorter than the P-rod / 1720T forestock. See here:https://www.pyramydair.com/product/benjamin-marauder-pcp-air-pistol?m=2367I scaled them based on the trigger frame and it looks like the P-rod forestock is about 45% longer.
From everything I've read, you should be fine with the 2400KT. The air tube is the same diameter so you can still use a QB tank block. Also, it comes with the steel breech and that is an essential piece in my opinion.It's a much better buy than taking a 2240 and building it up:2240 and parts$60 2240$25 shoulder stock$38 steel breech$20 24" .177 barrel$1432400KT configured the same way$93So yeah...I was a dum dum for building it from a 2240! I cut the air tube by wrapping a piece of blue painter's tape around the tube to help establish a square edge to follow. I then cut it with a hacksaw and finished squaring it up with a file, using the tank block to check for a good fit.