MK18 compact

thingiverse

If you play with NERF blasters without using shells, this remix of the Meaker's MK18 Assault Pistol might be just what you need. With a 100mm 5kg spring and 30mm compression length, this upgraded blaster can be loaded and fired by a six-year-old and still outperform my standard NERFs. This upgrade requires printing an almost complete original thing (R3 or R4) without certain parts: the plunger rod, plunger head, any shells or front attachments, and if your spring is less than 16mm in diameter, don't print the catch plate. Then print these replacement files: a thin plunger rod for springs with an ID greater than 13mm, and regular rods for those over 16mm; cl is the compression length (26mm: the spring compresses to 26mm, 30mm is easier). According to my research, it's better to use the regular rod whenever possible: a six-year-old can easily snap the thin plunger rod. Print also a plunger head for 28mm ID tubes with 21x3.5mm o-rings; yes, I got inspired by Cpt. Slug. A thin catch plate is only needed for the thin rod and slips into the rear part of the original catch plate. You will need one or two o-rings and some grease to complete this project. The barrel needs support but you can orient it properly so that only the "barrel" part needs support; the business end goes up! If you prefer, you can glue an anti-shock pad between the barrel and plunger (glue it to the barrel part of course); a washer-shaped piece of rubber or EPDM will do the trick.