Where do you think the energy to extract, eject, reset hammer, strip new round from magazine, chamber it, lock rollers behind it, comes from? WIth underpowered ammo, any part of the operating cycle can become problematic. Your description sounds like there's not enough energy for the ejector lever to kick the empty case off the extractor and clear the ejection port.
I don't know why people get their brand new, military spec firearm, and then are surprised when they have function problems in the first 100 rounds of Billy Bob's Soft Shootin' bargain basement ammo.
Someone will come along and say "quality firearms should function with any kind of ammo" and "properly made firearms shouldn't need a break in." If so then HK's suck because nothing else would explain the number of posts from people who have exactly the same problem you describe in their brand new guns.
Good luck getting it worked out.
ETA: Try this stuff: 500 Rounds of Bulk 9mm Ammo by Winchester - 124gr FMJ It's even cheaper than the PMC when you buy 1000 rds. You want somethijng with the circle cross headstamp.
Last edited by Slick; 12-24-2016 at 04:28 PM.
Someday this war's gonna end...
- LTC Kilgore
Like the others said clean it well, lube it generously, shoot a couple hundred rounds through, and I would bet you'd be good to go. Using full power NATO ammo would likely reduce the number of malfunctions you have on the way there. Do you plan on using a suppressor? Otherwise, I'd stick to using 124gr NATO. 147gr is fine, but I generally only use it with suppressor or with my carry guns (HP). For pistol caliber carbines, like my 9mm AR and HK-typr roller locks, I stick with the 9mm NATO.
I also stick with 124 grain for unsuppressed use and 147 only for suppressed. Generally 124 will have more energy. Buying 100 rounds of some different ammo to start with is a good idea. Then you can find which ammo cycles most reliably and accurately in your setup. Once you figure it out, then buy it by the case.
Start with the 124 after a good clean and lube. I'll bet it will be ok. But if not write to Zenith and they will take good care of you. In fact, better and faster care than many American manufactures.
Last edited by zephyr; 12-26-2016 at 12:34 PM.
I had the same experience with with Z5P when new. Everything mentioned by the others is correct. It had me concerned, but it was a combination of weak ammo and one of the mags causing the issue. I switched to 124gr for a couple hundred rounds and pulled the finicky mag out of rotation. The stiff charging has eased and now it runs like a sewing machine regardless of the ammo type. I never had any issues at all with the Z5RS purchased at the same time with any ammo.
Got her back out to the range today and it did much better after running 124gr thru it... Once my new ammo comes in with 100 x 147gr and the 1k x 124gr it should be fine......... I only had one failure to eject at this range this time..