Minx/Lynx2.1 Metric and performance mods

The parts include:

Silly Ram for M3 tapped holes in the transfer bar.

Guide nut with embossed M4 nut slot which improves sliding into the catch assembly. Needs to work in over 5-10 priming cycles.

Spacer designed for retaining short and cut K25 spring and keeping it centered. Works with longshot springs.

Plunger spacer for centering K25 which fits through a 13mm ID plunger guide.

Plunger thickened up to use 3mm/26mm ID o-ring and seal 38mm OD/35mm ID plunger tube. Print at 99%.

Pump with holes for M3 heat inserts 

Catch for K25 spring with plunger guide slot for 16 mm OD aluminium tube.

Catch with 4 mm recess to sneak in longer springs without precompression. 

Turnaround with slots for two 2mm/15mm ID o-rings to seal the barrel

Update: 13/08/2025

Added catch files with slots for 4mm PTFE centering tubing chunks as graciously advised by @fempoppy and designed in @HackOnWheels HIJINX. ❤! Dramatic reduction in misfiring and improved stability.

STL here has a little deeper cutout to take full length longshot springs and can be complimented with a 6mm ring insert if pre-compression is needed. Typically 170 fps on 14 kg Worker spring without pre-compression and 195 with a 6mm ring. 

Added Catch 2 with a slot for 1mm washer (16mm OD, 12.7 mm ID). Combination of DIN St37-2 mild steel for catch washer and SS304 for the plunger rod washer was found to prevent slippage and catch very reliably anywhere from 14 kg spring on Minx to a nested K25/K31 combo (ca. 300 fps on Lynx).

Update: 

Best combo for mechanical performance and catching at 200 fps so far are 1) brass washer in Catch 2 or 2) Full PC Catch 2 vs 304SS washer on the plunger rod