MP5 Single Shot fixed magazine lower, anyone try?

[jcwatchdog]

I just bought an Zf-5 MP5 clone, and a thumb tack was included to use as a regular fixed mag, but I also decided to buy the new 3D printed lower with the button that breaks the action.

I like the design and that someone actually came up with this idea. But has anyone actually fired it in this setup? It seems there’s a lot of play with the lower to the upper, and it seems to flex and it’s just kind of sloppy overall. It seems to function well as far as releasing the mag when the action opens, but will a 3D printer lower really hold up? I wish this could have been made under normal manufacturing processes instead of a 3D printer, but I know it’s not realistic to think anyone would bother.

[jcwatchdog]

No one at all?

[bwiese]

No one at all?

As you might remember single shotting exemption (SSE) scope was radically reduced ~2014 with
advent of AB1964.

These guns to my knowledge are not 'virgin' non-semiautos. At least they do have a bolt action.
If someone in CA had an MP5-esque such gun as a RAW and wanted to de-register it, or
someone had one before SSE restrictions were active, rendering them somehow in a fixed
10rd mag configuration - dunno how, somebody may have figured out one - would mean it'd
be transferrable to you.

[Thatonekidah]

I just picked one up last month and have put around 500 rounds through it. No problems at all with it.