I tried to go down this route last year. Like Eaglebeak said, if you want a regulated gun, buy a regulated gun. I received very poor response from Kral. You have several issues to deal with. The first is a very short barrel. It is bad on efficiency and power. The second is regulators, yes, they are available but you have to drill the bleed hole in the tank and the regulator occupies tank volume. In the end, after enduring all the mod costs, you still have an unregulated gun with a regulator that may work well, or not. You might as well spring for the Crown. Your cost will be the same, but the Crown is infinitely better right out of the box..........You are lucky, you haven't bought the Jumbo yet.....I hope!
No offense, but things are not at all as bad as they may seem, even for cylinder guns. For the Jumbo and other Kral bottle guns please see the other comments -- a 25 USD paintball setup from Aliexpress goes a long way.
As regards the cylinder versions, there are several inline regs that fit. Lane may be the best. There is no need to drill a venthole. In my Puncher Pro, I proceeded as follows:
1. unscrewed the cylinder from the valve block. (The threadlocker required heating.)
2. then filed a 1mm venting channel perpendicular thru the thread of the valve block and made a 1mm indent at the end of the cylinder to align with it. Such a setup is standard.
3. put in an Audrius reg (30mm OD), which contrary to Lane requires some metal work to the valve block and the valve cap (the cap that screws into the valve block to retain the valve spring).
4. Unfortunately I failed to make pics. The short of it is that I ground down the valve block throat to make for a wider edge for the reg o-ring to seal against. Use fine sandpaper to remove scratches that cause air leaks. I was able to do this without specialized metalworking equipment -- the aluminum can be handled fairly easily.
5. then filed off the edge of the valve cap that previously set against the throat of the valve block. This creates clearance for the reg seal against the valve block and enables screwing the cap further into the valve block to increase the valve spring preload.
6. As usual, I opened up the ports (max 4.5mm in my .25), lightened the hammer, and experimented with hammer spring preload. Vetmx, THammer, Motorhead and others describe this in another thread re: the Jumbo.
Result: great consistency, accuracy and much less action stress. I would not recommend this for my other Krals, which are fine unregulated. However I thought the 580mm long barrel and gorgeous stock of the Pro required special treatment.
