Airsoft HPA SCR Lower and Gearbox

thingiverse

Change Log: 2/24/2021 - Original post 2/28/2021 - Added printer friendly model. This version come in 2 of the same model. The base model is pre-cut for easy bed placement for printing. The second, "pre set" version, is the same, but placed at the appropriate angle already for printing without supports. 3/6/2021 - Added "SC" files for left gearbox shell and the trigger sear that SHOULD allow for the use of standard trigger contacts for some HPA engines. Also updated the trigger sear with a larger rod opening in the rear to allow better assembly. 3/7/2021 - Added basic straight trigger design 8/14/2021 - Added preset support model. (Prusa Slicer) Future Plans: - Variants for different uppers (G&G, Igniz PAAR15 planned) to allow for more variety of builds. - "Ease of install" changes, wire slot in the rear - Safety/selector (More than semi only) Discord for discussions and easy feedback on not just this design, but any SCR builds: https://discord.gg/4EXHBsn7qw This design is based on the ARES SCR, with certain adjustments made for airsoft. The design is meant to be used with HPA cylinder replacing units, primarily the Wolverine Inferno system with a Spartan trigger board. I believe that other systems will work, however caution should be taken with the electronics. The files included are for the lower itself, the gearbox, the trigger, the trigger bar (incorrectly named sear), and the trigger lock. Items required for the models to become functional: CYMA (or similarly designed) shotgun stock, M4 magazine catch and body pins, G&P upper receiver, and HPA engine (preferably Wolverine Spartan) with extended wiring. Some modification is required to get the wiring to the rear, and an untested design is in the works to fix this, but it is only a minor modification. A larger opening is needed to allow the wire harness to reach the stock. Depending on the stock used, a wire extension is needed to reach the end of the stock. This can easily be made with JST plugs, or purchased from your local airsoft store. Personal notes on this build: - I used this shotgun for the stock, as it's mounting point is similar to a standard airsoft M4's. (https://www.evike.com/products/60167/) - The gearbox has alignment tabs at the rear of the cylinder. This is intended to ensure a vertical alignment with the Inferno engine, as it does not have the normal locking holes. - Other upper receivers may work that are not G&P, however a slight increase in the width of the lower's internal dimension, as well as a minimal increase in its height, may make other models difficult to use. It is unknown if the original PAAR15 upper would fit. This is a modification of Igniz's PAAR15 lower receiver. Full credit goes to him for the base design of the receiver, as it allowed this model to be functional. (https://www.thingiverse.com/thing:4097329) The gearbox model is a modification of KK's model on grabcad. Again, credit to them for making a scaled version of the V2 gearbox that allowed for this to happen. (https://grabcad.com/library/afam-tactical-v2-g2-gearbox-1)