M865 Training Sabot 120mm Tank Round Cutaway Model

This is a highly detailed cutaway scale model of the General Dynamics M865 TPCSDS-T (Target Practice, Cone-Stabilized, Discarding Sabot with Tracer) round for the Rheinmetall L44 (M256) 120mm tank cannon used in the U.S. Abrams tank. This round is designed for target practice, and features an environmentally-friendly steel penetrator and a cone-stabilization system that limits its maximum range for use in smaller training environments. This model is based on the latest version of the M865 without the crazy sabot petal sealant.

This model was designed from measurements taken from real components, including the penetrator and tail cone assembly.  Unlike my models of the service rounds, I physically put calipers to component on every piece of this round. Some dimensions have been changed slightly to make the assembly printable without affecting the overall look of the model. It was also designed specifically to not require any painting or multimaterial system. Each component is printed in an individual color, and assembled after printing. Please be aware that this model requires glue to assemble.

There are two scales available, ¼ and ½. The ½ scale is slightly off, actually 45% scale due to the 256mm^3 build volume of the standard Bambu printer. Due to maximizing the size of the model based on print volume, the ½ scale model will not fit on anything less than a 256mm Z height without additional scaling or cutting down some parts. The STLs for the ½ and ¼ scale models are identical in geometry, just scaled appropriately.

Print settings and colors are as follows:

M865 Blank Stub Base: Grey or Silver. No special settings, but the primer holes come out better with a 0.16mm or lower layer height.

M865 Penetrator: Silver. 0.2mm layer height works, but for best results, print at 0.12mm in silk PLA with the outer wall slowed down as much as you can stomach. I used supports, but they're not strictly necessary.

M865 Stabilizing Cone: Grey. Printing on the top surface (smallest part) of the cone minimizes support requirements. Print with snug supports.

Universal Improved Spring Disc: Grey. No supports, no brim. Convex side down.

Universal Legacy Combustible Cartridge Case: White or a light silver. Print on the bottom (closed off end) with no supports. The curved portion at the bottom doesn't look great, but supports make it not fit well and the poor surfaces are hidden when assembled. Not sensitive to layer height at all.

M865 Combustible Cartridge Case Upper: Same color as the lower. Print on the small end with no supports and a brim. Not sensitive to layer height at all.

Universal Rear Obturator: Basic or Matte Black. Print on top (flat surface with no groove. Mine sticks with no brim, but if you need one, use inner brim only (hides post-processing better). Not sensitive to layer height at all.

M865 Propellant: Matte Black. Print with tree supports on build plate only. Reduce or turn off your infill to save filament, time, and the environment (I've printed multiple at 0%). Not sensitive to layer height at all.

M865 Sabot Petal: Silk Blue. Low layer height (0.12), slow outer wall, and tree supports (on build plate only). Print on bottom (smallest surface with smallest outer radius, same as the orientation when the model is assembled). Print 2.

Universal Tracer: Silk Gold. No special settings.

M865 Forward Case Adapter Ring: Translucent. I personally find that translucent ASA looks the most realistic, but I've gotten good results from PLA as well.

M865 Forward Obturator: This is the tricky one. Translucent (as above). REQUIRES tree supports on build plate only. Be very careful when removing supports as this part tends to come apart when removing them.

Assembly Instructions:

1. Glue Universal Rear Obturator to M865 Blank Stub Base.
2. Insert Universal Legacy Combustible Cartridge Case into M865 Blank Stub Base and glue in place. Ensure you press the parts together tightly.
3. Place glue inside the bottom of Universal Legacy Combustible Cartridge Case and place Universal Improved Spring Disc over the primer and press together. The Spring Disc should press fit around the primer base, but glue it anyway.
4. Glue the M865 Combustible Cartridge Case Upper to the top of M865 Propellant.
5. Glue the M865 Propellant assembly into the M865 Blank Stub Base assembly.
6. Place glue on the threads on one M865 Sabot Petal and glue it to M865 Penetrator. For best results, line up the seam on the penetrator where the two sabot petals will meet.
7. Glue the second M865 Sabot Petal to both the first petal and the M865 Penetrator.
8. Place glue on the upper horizontal channel in the M865 Sabot Petal assembly and rotate the M865 Forward Obturator into the channel. It should be as flush as possible.
9. Place glue in the lower channel on the M865 Sabot Petal assembly and rotate the M865 Forward Case Adapter Ring into the channel as above.
10. Place glue on the top (flat) surface of Universal Tracer and glue it into the bottom of M865 Stabilizing Cone, with the concave surface of the tracer facing the wide end of the cone.
11. Rotate the M865 Stabilizing Cone assembly into the M865 Propellant assembly, and line up the cutaway. Do not glue.
12. Place glue on the bottom of the sabot petals and the top of the M865 Stabilizing Cone assembly (the part that was on the print surface). Insert the M865 Sabot Petal assembly into the top of the M865 Propellant assembly, ensuring that the M865 Stabilizing Cone assembly fits into the hole at the bottom of the M865 Penetrator. Line the cutaway portion up and let dry.

If you have any tankers in your life, this makes a great and unique gift. It took years of collecting and dozens of hours to model, so I hope you enjoy. I'll be the first to admit that there are minor inaccuracies in this model - but they are basically all designed to make the model easily printable. Fellow K8s (or A8s, I guess you count too), go ahead and flame me in the comments. Everyone else, just enjoy, and be kind!