I had GhillieBear (HK aficionados will know this man) build me a MP5/10 from an FBI parts kit that I acquired. There are not many of these around, since HK only made them for the FBI. The MP5/10 and 40 are definitely the redheaded stepchildren of the HK rollerdelayed family. This is mainly due to the short development time and little to no support after the FBI received their guns. Basically, HK got tired of trying to cater to all of the demands of one agency and went on to build bigger and better things (UMP). Leaving the FBI to figure out any issues on their own. The main issue being ammo selection.
I'll be documenting the journey of figuring out how different 10mm ammo performs. I'll let you decide how relevant this exercise is, since there are very few of these left in the wild.
Today I decided to test how standard 180 grain Magtech ammo performed, while wearing a can. I was using the HI-impulse locking piece and getting some ruptured cases, as well as some failure to feeds. These shouldn't be correlated, but more research is needed (I only had 50 rounds).
Let me know if you guys have any questions regarding this build or if you want to get one for yourself.

UPDATE: The failure to feed issue is due to the pistol brace endcap. One of the issues with the single pin receivers is that they're not fully constrained (like the G3 endcap) and rely on the fit on the rails of the receiver. By reducing the play between the rails and the endcap, the recoil spring is pushed back into the proper position. This is usually not an issue with 9mm, as its a shorter and tapered cartridge, reducing friction when being pushed out of the mag.