Frequently Asked Questions
1. What is the difference between “K Size” and “Full Size” lowers?
The K Size lower is specifically designed for the compact MP5K and SP5K platforms. It is shorter in overall length to accommodate the smaller receiver. The Full Size lower is designed for standard MP5, SP5, HK94, and full-size clone variants. Please ensure you select the size that matches your specific receiver, as these are not interchangeable.
2. What does “2 Push Pin” compatibility mean?
A “2 Push Pin” lower is designed for receivers that utilize both a front and rear push pin to secure the housing. While this is the standard for original-spec MP5s, many semi-auto civilian versions (like some SP5 models) use a “shelf” and a single rear pin.
Note: Please verify that your receiver has the front pin bushing before purchasing. If your receiver uses a shelf, these lowers will require professional “clipping and pinning” to fit.
3. What is included with an “Empty” lower?
Our Empty Lowers are stripped housings designed for users who already own a trigger pack. They do not include:
- Trigger pack internals
- Safety selector levers
- Push pins
- Ejector lever These are perfect for upgrading your current grip housing while reusing your existing high-quality internals.
4. Are these lowers compatible with clones (Century/MKE, Zenith, PTR)?
Yes, our lowers are designed to HK factory specifications. They are generally compatible with MKE (Century AP5/AP5-P), Zenith, and PTR clones that utilize the push-pin configuration. Due to the varying tolerances in clone manufacturing, minor hand-fitting may occasionally be required for a perfect seat.
5. Is the lower considered the “serialized” part of the gun?
No. In the MP5/HK platform, the upper receiver is the serialized firearm. Our lowers are considered non-serialized accessories and can be shipped directly to your door without the need for an FFL transfer.
6. Will these housings work with Binary or Ambi trigger packs?
Our lowers are machined/molded to accept standard-spec trigger packs. Most Ambidextrous and Binary packs will drop right in, provided they are the correct “K” or “Full Size” version to match the housing you purchased.