Zenith MP5 Cocking Tube Spacer

[Slytiger]

So last night my cocking tube cap fell out (after doing an HK slap reload) along with a strange piece I could not identify.

I fervently tried to reinstall the piece and cocking tube cap. In the end, I could not confidently put the spacer in without tons of lithium grease, and pounding on the Z-5RS with a rubber mallet and bubbafying things like an idiot. I decided to leave it alone like a smart human being.

I emailed Zenith and I was very frustrated and embarrassed that I could not fit the spacer in along with the cocking tube cap. Zenith emailed me back saying that unidentified part was called a spacer that is installed because of import laws and things of that sort.
This is their email:
"You can leave the spacer out of the cocking tube. It’s supposed to be in there for importation, but it doesn’t matter after that. When that part is installed, it prevents the barrel from being completely free-floating. Leaving it out may actually increase your accuracy at longer distances. All you need is the cocking tube end cap installed."

Without the spacer in the cocking tube, it allows the Z-5RS (mp5) to have a little more accuracy by free floating the barrel.
I am making this bread in case any other MP5 needs come across this mental challenge with the mentally delayed blowback weapons.

[fasth2]

I took the cap off my new POF PK to see if had the same sort of spacer, nothing there under the cap. Odd......

[jfk]

My guess that cap was used as part of the centering process in relation with the sight tower during welding. There's a possibility they forgot that piece in the gun during assembly. I use something similar during the build process to keep the tower straight in relation to the cocking tube while welding.

[Slytiger]

Thanks. I guess I may keep that piece then in case I ever build one. I really really like this series of rifles more than any other. Even over the AK

[JPB]

Mine had the same spacer. As JFK mentioned, I thought it may be part of a jig they used to ensure the tube was properly centered while welding. I struggle to make any importability linkages associated with this part. Oh, and once removed, the tube is no longer centered. Hangs to the left a little...

Maybe it's used to center uncentered tubes?

[NoScoE30]

Maybe it's used to center uncentered tubes?

Ding ding ding! We have a winner!

[jfk]

Mine had the same spacer. As JFK mentioned, I thought it may be part of a jig they used to ensure the tube was properly centered while welding. I struggle to make any importability linkages associated with this part. Oh, and once removed, the tube is no longer centered. Hangs to the left a little...

Maybe it's used to center uncentered tubes?

If that's the case, the plug was an improvised fix for the tube that wandered during welding. Try the gun with and without it and if the groups open up because the plug is putting pressure on the barrel, then it's up to you to return it for repair or live with it. Since it's a pistol caliber, it may not matter whether the plug is in or out as far as accuracy. The MP5K tube can be tricky due to the amount of welding needed. Heat from one side can pull the tube in a different direction. The key to having a straight tube is to use a jig and weld small tack welds in equal areas before finishing.

[rickj1nd]

Yes... Those are the correct assumptions. A corrective / preventative measure for an inherent flaw in the manufacturing process.
"Importation restriction"... BS

[556x45mm]

Just maybe, it's there to prevent a bayonet adaptor from being installed which would prevent it from being imported into the US. He Z43P has the same spacer.

[Chopstix Kid]

I don't believe it was left in there by accident. Likely used to keep the tube centered as many people complained early on about mis-centered cocking tubes. The down side is that the gun no longer features a floating barrrel if the plug is present. Curious to see if new MKE owners have the plug present.