by nguyenkvvn
"Long ago... and oh so far away..."
Public Release v1.0
- Frame - Internal Revision v56
- Grip - Internal Revision v13
The Groupie STR-15 is an AR-15 lower receiver designed exclusively for buffer-less upper receiver actions, and uses any Mossberg 500-series compatible stock/pistol-grip attachment. It is based off the Disruptive Solutions AR-15 lower (untested) and includes revisions for fitment and ease of installation.
Do NOT under any circumstance use this design with ANY upper receiver that requires a buffer tube. Catastrophic, and FATAL, damage WILL occur. The designer, and any affiliated or non-affiliated groups, cannot be held responsible or liable for any injuries or damages that occur with your use of this model.
It is imperative you read this entire document before beginning this project.
- Bufferless AR-15 Upper Receiver - Examples include Brownells AR-180, CMNG/PSA .22LR Dedicated Receiver, or CMNG .22LR Conversion Kit.
- Mossberg 500 compatible stock/pistol-grip - You can use any Mossberg 500 compatible stock, brace, pistol, or birdshead grip. Remember not to make an NFA configuration unless you are legally allowed to do so.
- AR-15 Lower Parts Kit - A lower parts kit of your choosing will do. Mil-spec is the minimum.
- AR-15 Fire Control Group - You will need a mil-spec AR-15 fire control group. (Sorry, no drop-in triggers!)
- x1 M3 x 0.5mm Thread, 8mm long, Socket Head Screw - You can find this from McMasterCarr with part number 91290A113. (You can get by without this, but your detent will be loose for your rear takedown.)
- x1 M8 x 1.25 mm Thread, 90 mm long, Socket Head Screw - (Optional) This is only needed if you plan to print the included birdshead grip.
- x1 3/8” T-50 - Needed if you plan to use TheDecliner's trigger
You may find that a set of files will come in handy for your specific print's fitment.
- Print the receiver.
- Print the desired trigger. (TheDecliner's trigger is STRONGLY recommended, as the plastic triggers have a limited life span.)
- Complete the receiver with the lower parts kit. You might need a conical file to enlarge the hole as necessary on both the receiver and the trigger, but only ever so slightly.
- Test the fitment of the printed trigger bow. (Make sure you can put it in and out of the receiver easily!) If the fitment is successful, assemble the fire control group with the appropriate springs. Set aside the mil-spec trigger- it won't be used for this build (yet).
- Test the fitment of the fire selector. File the receiver as necessary for a snug, but not overly tight, fit.
- Assemble the rest of the receiver with the fire control group. Be careful not to drop the hammer onto the frame.
- Perform a function test of the fire control group- does the hammer drop? Does the disconnector work? What about the safety?
- Assemble the upper receiver onto the lower, and perform another function check.
- Print the epoxy trigger.
- Cut off and sand FLUSH the trigger bow of a mil-spec AR-15 trigger.
- Test fitment of the epoxy trigger mate onto the AR-15 trigger.
- If fitment is successful, use epoxy to bond the parts. Bind the parts in a vice, and leave to cure overnight.
Instructions for his trigger can be found in the root folder, in "TheDecliner's Triggers". Follow the instructions for those triggers.
- It is recommended to print the receiver upside-down. (That is, the space where the upper receiver would go is against the build plate.)
- Tree supports are not recommended if printing upside-down.
- eSUN PLA+ is the required filament if you are using any caliber that is NOT a .22LR.
- You must print the trigger on the side for maximum bonding and strength.
- Print HOT and SLOW for maximum bonding and strength. (50 mm/s and 230 C is recommended.)
- Private Beta v0.01
- Initial test model.
- Private Beta v0.02
- Inclusion of birdshead pistol grip
- Amended README.md to remove incorrect instructions
- Shape of M500 mount is revised to accomodate OEM Mossberg 500/Maverick 88 polymer stocks
- Errant fitment issue resolved by offsetting the face against the rear of the upper receiver. (This was splitting the front takedown pin hole.)
- Private Beta v0.03
- Revised trigger guard extrusion to reflect updated mounting assembly
- Revised birdshead grip for updated mounting assembly
- Private Beta v0.04
- Update to trigger bows
- Inclusion of epoxy trigger option
- Private Beta v0.05
- Removed legacy selector detent in fire control pocket
- Public Release v1.00
- Added in TheDecliner's trigger set
MIT License
- I require you do not charge others for access, nor rehost outside of personal, private archives. This introduces the possibility of stale files and out-of-date shares, which may be dangerous of a critical fix/patch distribution is required.
- Official sources shall only include Vinh's GitHub (@nguyenkvvn), and Deterrence Dispensed's LBRY archives. (Hot linking is perfectly okay!)