Sunday, August 28, 2016

Review - Prexis Sten ZK Side-fed Upper

I like the WeaponsGuild forums – they have a great community and the users there have a wealth of knowledge, but recently Mike “Jestism” Jestis banned Ian Mccollum from Fortgotten Weapons for giving an honest review on his own website.  I never followed up with my Prexis (aka Hellbox Armory) Sidefed AR15 (PSF15) upper that I was on a waiting list for over a year and because I thought he was an honest seller, and I’ve seen how he offered to make things right with some customers on the forums, and I felt like I already waited too long to complain after getting bogged with my own life of non-gun-related things, so I just let the whole thing go.

A day that will live in infamy.
Never forget.
Now that I know that Mike Jestis is truly a wanker on par with Gary Graham AKA “Weaponeer,” (or whatever the hell he’s calling himself now) I’m just going to go ahead and post my review of his so-called ZK Side Fed Upper (sometimes also referred to as the Prexis Sten Upper).  I’d rather not get banned from WeaponsGuild, but if he bans me for this, so be it.

Out of the box.
In 2009, I always wanted a pistol caliber carbine.  At the time, 7.62x25 ammo was cheap (1,100 round can for $90).  The Prexis Sidefed Upper (sometimes called the ZK Upper) product advertised that you could use cheap PPS-43 35 round magazines and did not need to change out the buffer assembly and magwell, unlike the traditional AR-9mm setup.  One would simply need to drop in the Prexis Sidefed Upper assembly and be ready to shoot.

Quick mock-up, before final fitting.
I received the Prexis Side Fed upper kit back in September 2010 after waiting nearly fourteen months.  I ordered the kit version because it was cheaper than the assembled version, but I knew that it was going to require work, which was just fine with me.  I was not impressed when I opened the package.  The upper receiver appeared to be made of a thick DOM steel tubing, the takedown pin attachment points were attached via ugly-looking blob welds, and I think the finish was some kind of spray paint.  The machining of the components looked good, though – I’ll give him that - but that does me no good when they don’t even safely function.

Stripped upper.
It was a kit gun, which meant some assembly was required - I knew that.  I’m not completely incompetant - I can build functioning AKs and AR15s and scratch-build my own receivers and finish guns that headspace properly and don’t fire out of battery.  But the kit seemed simple:  Attach magwell via two 8-32 screws, fit and finalize headspace by pressing in barrel and pinning it in place as you would an AK47, and finally attach the provided scope-rail.

Short-chambered barrel will cause
case-head separations.
After headspacing and pinning the barrel, I took it to my range for a few rounds of test firing.  The three rounds I shot gave me mangled brass.  Upon close inspection of the barrel with a round, I could see that there was too much case head exposed.  According to the headspace gauge it should have passed, but I guess I overlooked that.  I even asked Jestism if these barrels were fully chambered before I purchased this and he assured me they were.

Blown-out primer AND
a case-head separation.

I ended up milling off about ~0.22” from the rear of the barrel and reamed the chamber further through with a 7.62x25 tokarev reamer, so that was one reason I never bothered Jestism about fixing it, because I already fixed it my damn self.  I had already took matters into my own hands and made major modifications that I felt voided any refund or response, plus it was quicker than having to wait around to get my barrel fixed.

Blown primer.

Second, look at this shit.  I didn’t really think anything much of it at first, because I’ve seen boltfaces that had huge firing pin holes before that fired fine.  The firing pin hole is large enough that the firing pin can puncture the primers and the case can backfire and shoot debris through the hole at the shooter.  The surplus ammo was worse and brass would shred through the firing pin hole, binding the firing pin.  This could potentially cause a slam-fire.  This gun is not safe to shoot without completely rebuilding the bolt and re-chambering the barrel.

Scant, out-dated two-page instruction.
Note the PPS-43 magazine.
Oh yeah, Jestism forgot to mention that the finished product no longer takes PPS-43 magazines, as was advertised on every single one of his pictures, posts, and website.  About a week after I received mine – I found out that the reason my weapon wasn’t feeding at all was because now it takes modified PPSH-41 magazines.  Thanks for not mentioning that, whatsoever! It wasn’t mentioned in the 2-page instruction print-out that came with the upper (which literally said "USE PPS-43 Magazines"), not via e-mail, not on the official product website, not in a post-it note, and not on the official product thread.  I spent hours pouring over every thread related to this product to find a one-sentence reply from Jestism, which was buried in a 40+ page thread, that my PPS-43 magazines won’t work.
So basically magazines for this gun don’t even exist.  You have to make them by first removing the steel jacket that’s spot welded onto the PPSh-41 magazine and cut the magazine release slot with dremel and file.
Another magwell close-up.

So I ordered a couple of PPSh-41 magazines.  I don’t particularly like them since they’re single feed, which means they’re harder to load, plus they require modification, which makes them worthless for everygun that uses them except this “Sidefed Upper.”  I don’t like modifying magazines and I hate proprietary magazines.  A magazine should work right out of the box.

Magwell mod.
After finally getting a single magazine done, I find that the magazine has a worse fit than the PPS-43 magazine for some reason.  Which makes sense, since this gun was designed, originally, to run on PPS-43 magazines but for some last-minute reason does not.  It wobbles back and forth and my solution for this was to install a 8-32 screw in the inside rear of the magwell so it could take slack from the wobble motion of the magazine.

It fed about 85% of the time, which is 85 more than 0, so that was good, I guess.   So after fixing the broken barrel, and the magazine feed issue, that still left me with a worthless bolt which I now have to fix myself or re-create from the ground up.

It was at that point I gave up.  I ended up buying parts for a 9mm AR and was satisfied with that.  I was, at the time, pretty busy and I don’t spend all damn day in my garage building guns and shit, if you can believe that.  I spend about an hour or two a month at most.  By the time I got to where the gun fed from the magazine and had proper headspace, a year had gone by and I figured it just wasn’t worth my time or his.  I have some ideas how I can fabricate my own bolt from other bolts that use common parts and share similar bolt body diameter.  That way I don’t have to worry if this hacksmith will charge me to replace my extractor down the line or blacklist me for not taking part in his circle jerk forum posts.

I’m still going to use weaponsguild, because like I said, the people there are friendly, helpful and knowledgable even if the owner is a two-faced bastard, and it’s a different place than or  I will definitely be avoiding any Prexis/Hell Box Armory products in the future.  Here's some random pictures.

PPS-43 magazine and chamber.
The package.
It was wrapped really, really, nicely.

Close-up of the magwell.
The root cause of blown-out primers.

The bolt.

"Mike, I can't believe I fucking died for this!"

This would be cool if it functioned,
but it doesn't.
Links, Resources, etc.

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