[AK43]

I've shot my old HKMP5 suppressed and I did not have to change the locking piece. My MP5K will not work correctly so I ordered a #28 locking piece for it. My question is can i leave it in or do i need to take out when not using the suppressor. Greatly appreciate your advice.

 

[Chopstix Kid]

Take it out when not using the suppressor or else the gun may not cycle.

Oddly, however, your gun (MP5K) should run fine with the standard LP and a suppressor albeit it will hit a little harder and exert more wear on the parts. The #28 is intended to slow the gun down a bit when running suppressed. Also note, the #28 is recommended when shooting 147gr or heavier subsonic with a suppressor. If you run 124gr or 115gr subsonic with your suppressor, the #28 LP is not typically necessary--assuming you have a factory gun or a clone that is make fairly close to spec.

 

[JTinIN]

While Chopstix Kid is correct, as usual ;-)l, one may for for non critical applications in some MP5Ks with some bolt/locking pieces and with some ammo (add any more disclaimers here that I missed ;-) leave the number 28 locking piece in and find a clean and lubed gun runs fine for many hundreds of rounds. The couple years (old days before the new crop of fast HK gun smiths) the full size MP5 was out to the shop for a rebuild, I tried running the number 28 locking piece in the MP5K-PDW and it worked fine with me and had a slower cycle rate for shooting steel targets in a match setting (never did shoot the match as was too busy helping ;-). I typically was shooting 124gr NATO by whom ever was loading USGI ammo that decade.

Of course if you would be using the MP5K-PDW for any day job or even a major subgun match that you would care what your score was, then would of course go with OEM recommendations as you have a lower "impulse" energy reserve with the #28 locking piece.

 

[kwesi]

G3Kurz answered this question some time ago (I tried to find his reply). IIRC he stated that some MP5K PDW with or without a suppressor with need the #28. I once owned a CA89K that had FTE's and it was only after reading G3's post at I switched to the #28 LP & it did the trick.

 

[HkCHUCK]

JTinIndiana

I run 124 gr FMJ in my MP5k-PDW without the suppressor and the #28 locking piece all the time now without any problems, too. I do clean the
weapon and lubed it up after each time I take it to the range. Often I clean it two or three times before I take it out again which to some
may seem excessive.

 

[AK43]

I appreciate all the info from all of you. It was very helpful.FTE's is my problem. Thank You!

 

[Chopstix Kid]

Extractor spring/extractor or short-stroking. However, in a K-gun excessively high ROF can also cause extraction issues which likely what you are experiencing... MP5K + 100 or 110 LP + suppressed = higher than normal ROF. Also check the extractor spring.

@JT -- nah man, I'm wrong, a lot... It's just usually my wife that brings it to my attention, lol.

 

[AK43]

Thank You. I will order a new one just to make sure. I've ordered a few new parts but left it out of the list

 

[JTinIN]

@JT -- nah man, I'm wrong, a lot... It's just usually my wife that brings it to my attention, lol.

In my case figure if the wife said was ok to get a machine gun years ago, did not have as many complaints. The actual answer was "Yes but don't known why you would want to" ... the increase of prices, on paper, has helped. Note only count a gun as a machine gun if it has a belt and is not a host gun ....