Z-5RS Feeding Issues and Failures to Eject - Purchased June 2019
Purchased Zenith z-5rs from KellyEnterprises back in June. The gun is very cool. Paint finish wasn't perfect but I figured its a shooter so I'll live with that.
Put SB Brace and MI hand guard on it immediately. Ergos on it are excellent. No issues with magazine wobble. Trigger is actually pretty nice, especially compared to factory PTR91 trigger. Tri-lug finish is worn off for some reason and not timed correctly but this is more cosmetic than functional. Suppressor fits on fine. Took out to shoot for the first time on 7/4 to celebrate America by shooting a Turkish MP5 clone. Makes sense.
Very soft shooting and even ran a SiCo Hybrid on it. Took my kids and nieces and nephews and brothers in law. Everyone had fun although it did experience some issues on that trip. Shot 147 gr Speer Lawman with feeding issues. Was not ejecting and then loaded a 2nd round. Had to eject magazine, clear gun, and reinsert magazine several times. Tried 115 gr Silver Bear and experienced same issues. Still, we got through about 60 rounds with about 5-6 malfunctions.
Thought it could be the MKE magazine so I tried HK German magazine on another day with 3 different types of ammo, suppressed and unsuppressed.
Experienced similar results again only worse this time. Worst ammunition in this firearm was CCI Aluminum 147 gr. Couldn't get 2 rounds in a row without a malfunction. It was even damaging the next round in the magazine almost every time. Silver Bear 115 gr was the other ammo used and experienced similar issues. Spent casings actually got lodged under the bolt on 2 separate occasions requiring me to remove pins and separate the lower just to remove the casing.
Best performing that I had with me that day was American Eagle 115 gr.
Contacted Zenith Warranty service as I was leaving range and they were A+ on customer service. No long waits on hold and a woman named Danielle was very courteous. Had me send in photos after taking down a description of my issues.
I got an email with a prepaid label and instructions on how to return. Just shipped it back today.
They did mention in their response email that aluminum cased ammunition does not work in their firearms. I found this interesting since it doesn't say anything on their website about it.
It does say they do not recommend any type of Federal American Eagle. Funny because that's the only ammunition that worked decent in it.
Anyways, I've heard good things about their warranty service so I'm hopeful that they will get the gun running reliably. I get that this sort of thing can happen.
I never post things like this because I've never had to send a gun back in for warranty work.
I thought the information could be useful though to recent buyers who might be experiencing similar issues.
I'll post here how long it takes to get the gun back, what they tell me they did, and how it works when I get it back.
I sincerely hope its all good when I get it back so that I can relay how awesome the Z-5RS is. I believe in giving companies a chance to make things right and then giving them positive publicity for it as well.
If it helps put your mind at ease, I had very similar issues with three of the Zenith guns we purchased for our police department and Zenith couldn't have possibly have handled it any better! By now I am convinced that this was a common issue among that shipment of guns. I'm only 20 minutes away from them, so we are fortunate to be able to just run them over there when we have an issue. I took them over late last week and by yesterday morning JR from their custom shop and armory showed up at our front door with them, ready to go the range. Whatever small adjustments he made (even though I am an armorer I'm not sure what tweaks he made, the level that he is working on is way above my competence level) I can say that both the RS's and the Z5K ran like sewing machines on both full auto and semi. We put several hundred rounds through them and had zero malfunctions whatsoever. So my point is that although there have been some consistent issues reported with this latest batch, Zenith appears to be all over it and their customer service is fantastic. I hope you experience the same results!
i had a very similar problem with my coharie, couldn't find anything online about it..ended up just buying a F type bolt head which ultimately fixed the issue. After looking at both bolt heads side by side i noticed the coharie bolt face didn't hold the round in place very well and had some slight play (even with brand new factory hk extractor and spring), where as the F type was extremely tight with no play.
I had the same issues and their turnaround was fast. From their note, the case deflector rivets were loose. They also installed a new extractor spring, adjusted the magwell and magazine catch. Haven't fired it yet, but I expect the problems will be gone.
Update Warranty Work
Received Z5RS back yesterday 7/29.
Very quick turn around.
Notes from Gunsmith:
Adjuster case deflector for proper clearance
Installed new extractor spring
Touched up paint
Installed picatinny optic rail
They also fired three 10-round groups of different grain ammo totalling 30 rounds. 123 gr ZQI, 115 gr WWB, and 147 flatnose WWB.
They did tell me before any warranty work was completed that aluminum ammo won’t cycle.
Finish was clearly improved although that was the least of my issues if it would just run.
Took it out today to shoot Blazer Brass 115 gr, Silver Bear 115 gr, and even a little Blazer aluminum just to see if it would work now.
Chewed through everything fine except the aluminum. I don’t think it’s any fault of the gun so much as the mp5 feed ramp and extraction design. The main culprit being the softer nature of the aluminum casing. They feed fine for the first round but they don’t seem to extract or feed well after that. All good. I can live with shooting brass and steel. Overall, pleased with the gun and very pleased with Zenith customer service/Warranty work.
I don't think the fluted chamber in any roller lock system likes the aluminum cased rounds. I think I remember (it's been years ago so don't quote me) from the operator course that the aluminum alloy used in most of the CCI stuff is harder than brass and that the fluted chamber, designed to aid in extraction by instantly re-sizing the brass case during the extraction phase of cycling, doesn't work as well with harder aluminum alloy. This means more friction along the case wall during extraction, thus less reliable functioning. Again, a smarter fella may chime in and I am willing to be corrected.
At any rate, very happy to see that you got it back in good order! I was very confident those guys would square it away!