TP50 Gen2 Rail Speedloader – 4 or 6x .50 cal, refill while mounted (Umarex T4E)

Description:

Rail-mounted speedloader for the Umarex T4E TP50 Gen2. Holds 4 or 6 extra .50 cal balls and feeds them straight into the magazine port, without removing it from the gun. Designed from a 3D scan of the gun (with AI assistance) and tested on a real TP50 Gen2.

Two versions

• Standard (6 balls): two staggered rows, carries one full magazine refill.

• Slim (4 balls): single row, 11 mm lower and sleeker. 6 in the magazine + 4 in the loader = 10 shots, about one 12g CO2 capsule. New version, based on the tested standard design.

Both versions use the same rail fit, stop position and feeding system.

Features

• Slides onto the Picatinny rail under the barrel. Push it fully back and it stops against the trigger guard, so it’s always in the right position to feed.

• Holds 6 (standard) or 4 (slim) balls, .50 cal / 12.7 mm.

• Refill from the front while mounted: push balls in and two one-way flex lips stop them from rolling back out.

• Reload: set the magazine spring lever to the loading position and tilt the gun back. The balls drop into the magazine port.

• Side windows show how many balls are left.

• Full-length Picatinny rail underneath for a light or laser.

• Does not extend past the muzzle.

• Optional M3 (16–25 mm) screw locks it in the rail slot. It self-taps, no nut needed. Without the screw the friction fit is usually enough.

Compatibility

• ✅ Made for the Umarex T4E TP50 Gen2.

• ❌ Not designed for the TP50 Compact, TR50 or HDR50.

📷 Photos show the Dutch version of the TP50 Gen2 (no slide serrations). The international version has serrations on the slide but the same frame and rail.

Which file do I print?

1. Print TP50_rail_fit_test_4x.stl first: 4 small clips, about 10 minutes. The notches on top show the clearance per side:

   • 1 notch = 0.10 mm (tight)

   • 2 notches = 0.15 mm (standard)

   • 3 notches = 0.20 mm (relaxed)

   • 4 notches = 0.25 mm (loose)

2. Slide the clips onto the rail from the front. Pick the one that slides on with light resistance and doesn’t wobble.

3. Print the speedloader with the same clearance:

   • Standard (6 balls): TP50_speedloader_v4.6_clearance_0.XXmm.stl

   • Slim (4 balls): TP50_speedloader_slim4_clearance_0.XXmm.stl

Every printer prints a bit differently, so this 10-minute test can save you a failed full print.

Print settings

• Material: PLA Tough / PLA+ or PETG. Plain PLA is not recommended, because the flex lips can crack.

• Layer height 0.2 mm, 4–5 perimeters, 15–30% infill.

• No supports. Print as oriented in the file, with the bottom rail on the bed. All overhangs are 45° or less. The longest bridges are the top edges of the side windows (~35 mm standard, ~43 mm slim), which print fine with normal bridge settings.

• Use the same filament and settings as for the fit test.

Mounting & use

1. Slide it onto the rail from the front and push it fully back until it stops. The front is then flush with the muzzle.

2. Optional: lock it with an M3 screw (16–25 mm) through the side hole.

3. Refill: push balls into the front hole one by one, with your finger off the trigger.

4. Reload into the magazine: set the spring lever to the loading position and tilt the gun back.

5. Unload the speedloader: slide it off the rail and turn it upside down. The balls roll out through the feed hole on top.

Safety & legal
This is an accessory for a CO2 less-lethal training marker. The refill hole sits right below the muzzle, so keep your finger off the trigger when refilling. Check your local laws on owning and carrying this type of device.

License
This design is free for personal use only. Selling prints or files, or using this design commercially in any other way, is not allowed.

☕ Support my work
I originally planned to sell this design, but I decided to share the files for free so everyone can enjoy it. A lot of time, prints and filament went into getting this right.
If your print turned out well and you like it, buy me a coffee on Ko-fi ☕. Every contribution, big or small, helps me keep designing!
Thanks, and happy (spaghetti-free) printing!