This week we've seen the upload of the SF5: a 3D printable MP5 receiver set from @navigoboom. The SF5 is compatible with OEM HK parts, PTR parts, RCM parts, and most of the other clone or US-made MP5 parts. An improved iteration of the KF5 platform, the rifle was developed as a hobby project meant to sell surplus parts kits, similar to the NylAug.
The Yeet22 (Versions 2 and 3) from s**tonwheels is a relatively compact, primarily printed semi-automatic 22LR. Notably, the gun's internal mechanisms are all designed and optimized for 3D printing. This is a true experiment in the medium.
HulkhoganHH and TumbleDryOnLowHeat have taken the same adventurous approach with their recent revision of the "El Ratto" 22LR semi-automatic pistol, and its smooth simplicity really shines. Outside of any innovations in manufacturing, this trend in component redesign may be the most valuable in DIY Defense.
DEFCAD promotes DIY defense documents even when the newsletter doesn’t highlight them. This week we make special mention of the FMX Revised Black Book of explosives. Much in the same vein as the classic Anarchist Cookbook, the FMX Guide serves as a general introduction to the chemistry of home-manufacturable explosives and their specific modes of manufacture. The text has no fat, and it jumps right to instruction, never digressing into dead end commentary.
The Handbook of Weaponry actually has real explorations of practical explosives chemistry. This book is probably the single best introduction to this study of the creation of ordinance.
Forged Carbon Fibre Using Compression Moulding
Though not obvious, it's becoming clearer every day that the DIY Defense space has backed itself into a funny corner. Relying on cheap 3D printers to directly produce finished components, when we know that 3DP is meant more for prototyping, acculturates us to accept undue limitations of our thinking. DEFCAD has nothing but respect for the ground gained while we embraced these limitations, but it's alwasy a good time to review our techniques. A middle ground in innovation (between extremely expensive printer setups and pure Ender 3 PLA+ fun times) may come from the automotive industry of all places.
Easy Composites Limited has this excellent introduction to making Carbon Fiber/Epoxy components using 3D printed compression moulds. It's incredible how simple it is to just layer carbon fiber chopped tow with epoxy and enure it's under tension during set and cure. The theory is sound, the raw components cheap, the methods are accessible, and it looks like the final parts can compete directly with aluminum. Perhaps there's a downside in more manual post processing of components, but there is no single DIY fabrication method that avoids some level of this. We're excited to see who takes up this design choice in 2024, and we'll promote the results.
Futuristic, strange and iconic. These words evoke many images when we think of firearms, but no style of design embodies them better than the bullpup. There's a hopeful futurism in the outlines of the FN P90 and the Steyr AUG, a practicality and utility to the FAMAS and the IWI Tavor, and something raw and powerfyl in the design of the Barrett M82A2 or the H&K XM25. All of these weapon systems belong to the misfit family of the bullpups, which, almost in spite of their reputations, deserve their fame.
The P90 is a PDW chambered in a tiny rifle round, the FAMAS is a three-round burst rifle with a 25 round mag, and the XM25 is a 25mm airburst grenade launcher. "Bullpup" is not a term in reference to a specific role, but is instad one of specific construction. To be a bullpup, the firearm must meet only one requirement: the breech needs to be placed behind the trigger. Magazine orientation and position is up to the designer, the overall length doesn’t matter, nor does the caliber or feature set.
The primary advantage of the bullpup configuration is that you can ultimately reduce the overall length of the weapon without needing to cut down on the barrel length. By simply shifting the firing mechanism rearward (usually into the stock), you can shorten the entire platform. This, in turn, allows for better recoil control with the recoil impulse and center of mass being closer to the shoulder. Another advantage is that, by retaining the full length of the barrel, the platform can retain muzzle velocity, and thus retain ballistic performance.
If the accolades are deserved, why aren’t bullpups more common? Simply put: Ergonomics. The biggest detraction of bullpup design is that, by shortening the overall length, you’re also bringing everything closer to your face, which means muzzle blast, muzzle flash, heat, and residual exhaust. Furthering the point of ergonomics, both magazine changes and trigger controls are known to be a bit more awkward than with conventional platforms, with magazine changes being non-intuitive (meaning retraining the shooter) and trigger systems being less responsive (meaning being outclassed in precision fire). In addition, the shooter’s vitals are that much closer to the breech in the event of catastrophic failure, as unlikely as it is in modern arms design.