This is my TM Hi-Capa 4.3 D.O.R.
At first glance, it may look fairly simple, but there are actually quite a few things going on.
The biggest change is the blowback unit. It has an ultra-lightweight nylon breech that is over 90% lighter than the stock breech. Even with the red dot installed, the moving mass of the slide assembly is still lighter than the stock setup.
I also modified the base of the inner barrel and paired it with a semi-cylindrical contact-patch hop bucking — what we would call a “kamaboko-shaped” contact patch in Japanese — to improve on the already excellent stock accuracy.
The optic is a NOBLEX OS replica. The 4.3 D.O.R high-mount plate was originally designed for the Tokyo Marui Micro Pro Sight / DOCTOR-style footprint, so this optic does not fit out of the box. I modified the plate to accept a wider footprint while keeping the position and overall appearance as natural as possible.
The weapon light is an SBAL-PL replica. I really like how it sits almost flush with the muzzle.
I also changed the hammer spring housing to a more standard Hi-Capa-style shape. The stock palm-swell style grip did not feel bad, but it made the grip circumference a little too large for my hands. After swapping it, the side-to-side movement of the dot during rapid fire was almost completely gone.
Overall, I wanted to keep the basic 4.3 D.O.R look, add a bit of extra character, and build a practical red-dot Hi-Capa that still cycles extremely well even with an optic mounted.