Edit: Added some more detailed pics of the guts.
Two Fat Guys PB closed-bolt mech kit installed SP Ion with breach modified for Milsig Squarehead magazines and optimized for First Strike Rounds. Goldmember barrel, Supremacy FSR scope, integral suppressor, totally tool-free disassembly, real wood and steel, on-board air system averaging +/- 120 shots per 9ci tank fill.
This whole project was a real labor of love. I had many design goals going into this project and I'm surprisingly satisfied with the end results. The closed-bolt kit from Yoda was key to getting this thing as efficient and consistent as possible with the added effect of further reducing report below what I could have ever anticipated, and going mechanical as a whole made it stupid simple to implement when all was said and done.
I am very happy with the performance of the FSRs and the Goldmember barrel and the integral suppressor has been far more effective than I had ever anticipated. Keep in mind the suppressor cannot be affixed to any other PB markers let alone real steel - but even so it lives in a legal gray area and I do not recommend anyone else attempt to make one without fully researching your local laws.
Build Notes: This project took many years to complete and as most projects go, went through a few major iterations. Initially I tried to make this out of a Tipx, then an Automag, then finally gave in and used an Ion - which turned out to be a total blessing. The ion was cheap, modular, highly customizable, and plentiful enough that it didnt worry me to cut away on one or two or three til I had what I needed.
The body and stock is from a King Arms VSS airsoft build and was of surprisingly high quality. The dust plate is a real AK steel part and the stock is genuine wood (still need to sand and stain it as of the time of this posting). I cut out space in the stock to fit a regulator through the grip and cut a slot to route an on/off from the buttplate to grip. Just used a bunch of Bacci sourced fittings to do that, nothing too special. Lots of m-m and f-m fittings were needed.
The breach was cut to fit squarehead magazines. I selected these mags for 2 reasons: First, I had familiarity with every commercially available magazine at the time and these were the only ones with a protruding collar and the internal rotation that is CRUTIAL for feeding 18+ first strike rounds with even pressure and no flips. Second, I already owned a bunch so it was a no brainer. To line up the magazine with the breach properly, I made sure the mags would seat high enough in the breach so that the bolt gently glides across the top of the magazine collar. This hinders FSR flips and creates a greater seal, preventing inefficiencies and noise seap out of the breach. After sizing how far back the breach needed to go, I went to work with a dremel and cut the everloving **** out of it til it fit right. Slow, systematic, methodical. One thing of note- I ended up removing the barrel oring in the ion breach because there was no way to fit a magazine in there otherwise. No worries, it wasnt going to be useful anyway. Finally, I needed to fabricate parts to depress the magazine detent when inserted. You'll see the blue plastic bars doing that job. Not pretty but highly functional and reinforced for rough play.
The trigger was fabricated from an AGD trigger frame and positioned inside the VSS trigger guard in a way that made it easy to actuate the SMAV 3 Way plunger of the mech kit. After that everything just sort of fell together more like a piece of art than an engineered design.
A note about milsim: Most of the time, milsim paint guns are built at the detriment of functionality. My goal from the outset of the project was to replicate a real steel rifle for milsim purposes while maximizing potential for usefulness on the paintball field. The VSS, with its unique wood stock, compact yet wide AK style body, and integral suppressor aligned perfectly with my needs. Highly modular, this one is set up as my long range FSR workhorse but can also be transformed into a CQB carbine with little effort.
I owe a huge debt of gratitude to my very good friend and mentor, Punisher68, who not only advised me on everything Smart Parts and helped me source parts - but also for hiring my *** as a coworker so I could afford to keep pumping money into this project over the years. I also must sing the praises of Jacob and Jonathan of Two Fat Guys PB for all their amazing engineering and moron support. And of course, I HAVE to thank good ol Daniel Bacci and his wonderful fantastic amazing archive of random spare parts, plus hes just such a nice dude!