Why RDMT's wound blocks separate bullet entry from bullet exit
Every arm and leg trainer ships with separate bullet entry and bullet exit blocks. The design decision behind that, and why one wound profile is never enough.
Every RD Medical Training arm and leg trainer ships with three interchangeable wound blocks, and two of them come as a pair: a bullet entry block and a bullet exit block. The arm's third block is a gash. The leg's third is a large shrapnel and puncture block. Shipping entry and exit as separate blocks, rather than one generic "gunshot" wound, is a deliberate design decision, and it is worth explaining.
A gunshot is one mechanism, but on a trainer it is two different problems. The entry block and the exit block present differently to the trainee's hands, so packing one is not the same rep as packing the other. A trainee who has only ever packed one presentation has practiced half of the scenario the instructor is actually trying to teach.
The deeper reason is variability itself. Most responsive limb trainers on the market have a fixed wound profile: the same scenario every time, so the tenth rep is a memorized copy of the first. Real training value comes from the trainee assessing what is in front of them before acting, and assessment only happens when the wound can change.
The blocks make that a between-rep operation. Simulated blood is pumped through the limb and exits through whichever block is installed, producing active bleeding. The trainee stops it with a tourniquet on the correct section, or by packing the wound block with gauze. Correct technique physically stops the flow. Incorrect technique does not. Then the instructor swaps the block, and the next trainee faces a different injury on the same limb.
The same design carries the economics. The wound block is the part that takes the packing, the gauze, and the wear, so it is the part built to be replaced, at $150 per block rather than the price of a new trainer. An instructor can expand the scenario library, or retire a worn block, without touching the rest of the unit.
This interchangeable-wound-block approach is the core of the product, and it is patent pending. It exists because the founders were contracted by the U.S. Army to improve TCCC training aids, and the combat medics they interviewed asked for training that was realistic, durable, and variable. Separate entry and exit blocks are what "variable" looks like when it is taken seriously: not one generic gunshot wound, but distinct practice on each presentation a scenario calls for.