SB tactical brace causing reliability issues Z5RS

[kawtech87]

Not sure where to post this. I picked up a Zenith Z5RS a couple weeks ago and bought a SB Tactical brace for it. I took it out today and with the factory but cap it's 100% reliable. Switch to the brace and it won't cycle the action. The action gets stuck all the way back and I have to to cycle the charging handle. It fires but then it's like the bolt locks open but it has no BHO. With the factory cap it runs great.

Anyone have any ideas on what could be going on? This is my first roller lock gun so I'm not really familiar with them.

 

[kawtech87]

Nothing?? No one has ever had any issues with an SB Tactical brace on a roller lock pistol?

So solution is to form 1 and SBR?

 

[jsx1043]

Don’t even know those were a thing, and now I’m jealous. Having shot a legit MP5 on burst and auto back in the day, the old German sewing machines are dear to my heart.

That being said, I’m not a gunsmith and definitely not familiar with the inner workings of the MP5. My guess might be some over tightening with the installation of the brace? Maybe some part of that installation that causes the catch - a different bolt length or a thickness of a mounting point or something?

 

[Cameramonkey]

Lubed up properly? My brand new AR9 pistol during the fitting and testing phase while it was still dry would hang briefly. Pull the charging handle and the bolt would hang for a half second. Once I lubed it up it ran fine.

 

[jstrahl]

I have a PTR 9c with the same brace and have quite a few rounds through it with no issues. I remember it was tight fit and I had to lightly tap it on, but nothing else unusual pops out at me about the installation.

 

[kawtech87]

Lubed up properly? My brand new AR9 pistol during the fitting and testing phase while it was still dry would hang briefly. Pull the charging handle and the bolt would hang for a half second. Once I lubed it up it ran fine.

I tried lube at the range. Didn't have anything in my range bag but a can of remoil. I may try something a little slicker and see what happens.

I'm wondering if the recoil spring isn't seating properly in the brace causing it to sit at a slight angle. Not sure how to test this hypothesis either as the pistol function checks fine after installation of the brace. It's only live fire that causes issues

 

[kawtech87]

I have a PTR 9c with the same brace and have quite a few rounds through it with no issues. I remember it was tight fit and I had to lightly tap it on, but nothing else unusual pops out at me about the installation.

You seem to be in the vast majority of people with braced MP5 clones. I've not found another instance of this happening to anyone else online. I'm going to call SB tactical and see if they have any ideas

 

[venenoindy]

I'm interested on buying one and have done extensive research and have not come across any other instances like yours, I even called Zenith a out feeding HP's and they were very helpful. Call Zenith and SB, Alabama arsenal channel on YouTube had one with a brace and he didn't experience any type of malfunction with his.

 

[venenoindy]

[video=youtube_share;53hXYWWIE0s]https://youtu.be/53hXYWWIE0s[/video]