Anyone build any roller-lock guns? Specifically MP5-style pistol caliber carbines.

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So I've "built" AR platform, AK platform, MAC style closed bolt, and Uzi-influenced closed bolt guns. By that I mean percentage built receivers and parts kits/demills, as well as made-from-scratch lowers with parts kits/demills. All of these guns are pretty well documented for home brewing (lots of information/resources) and don't take exceptional welding skills or crazy tolerances.

I've owned an SP-89 and two flavors of CETME/G3 but can't say I'm an expert in their operations let alone assembly beyond field stripping. In doing some digging it seems like there's not much info out there - maybe due to costs and popularity - compared to other platforms. Everyone makes some flavor of AR, many make some flavor of AK, and MACs/Uzis were cheap and common as dirt. HK not so much. So far fewer tutorials and not something you run across in armorers classes unless it's HK.

I've got a roller-lock style 9mm serialized receiver, less the trunnion, from a great manufacturer (if anyone other than HK can be said to be). I'm looking at demilled parts kits from $1,200 to $2,200 and a lot of people are saying that the tolerances around the trunnion are the toughest part... also that there's some tricky welding. It is apparently a great platform to drop a registered pre-may sear into.

So... who's got experience with these? $1,200 parts kits seem like a big gamble if something goes wrong. With the above builds under my belt and some gunsmithing experience, should I attempt this totally redundant build (I have several PCCs - then again, none are sear ready) or consider passing the receiver along?
 
My view on projects like that is, if it goes sideways, that sucks, but lesson learned and you can either fix it or take the lumps and move on. And if it DOES work out, you've got a great gun that you can be VERY proud of because you built it yourself.

On the other hand if you don't try it at all, you'll never know and you just might be kicking yourself 5 years down the line.
 
Roller locked flats are tough to work with if you don’t have the proper tools. Even “experts” have difficulty making a functional gun.

If you’re looking to try for fun, go for it. If the end-goal is a working firearm, there is no substitute for the real thing.
 
I bought a complete Omega upper from Atlantic firearms, waited on my stamp, then pieced a lower/fire control group together (easy). Honestly the most fun gun I've ever shot. I go through far too much 9mm with it.

AR builds about exhaust my comfort level when it comes to building. I've toyed around with the idea of an AK build but it just seems too complex for my tastes.
 
I bought a complete Omega upper from Atlantic firearms, waited on my stamp, then pieced a lower/fire control group together (easy). Honestly the most fun gun I've ever shot. I go through far too much 9mm with it.

AR builds about exhaust my comfort level when it comes to building. I've toyed around with the idea of an AK build but it just seems too complex for my tastes.

Find the Shovel AK-47 thread on this site. You might rethink whether you can build it in the backyard.
 
I tried to build an HK33 out of a flat and one of the $400 Mayalsian parts kits that were everywhere a few years ago. It's a nightmare if you are not someone who is particularly good at finesse and metal work, AK's are a breeze in comparison.

If I remember the total costs of what I spent, the kit was $400 +shipping, the flat and weld kit was like $300 from HKparts.net, the barrel was an other $225 off HKparts.net, then there's the mags. I stumbled on to a pile of 8 HK metal mags in a shop for $30 a piece, but a deal like that will probably never happen again. My friends already had the bending jig and a mandrel to massage the flat once bent, so I didn't have to buy the tooling at full cost, I think we all chipped in $20-50 or something like that. I ruined my first flat because I had the jig slightly off and had to buy a second, an other $100. Now I am at well over $1k into the rifle and I needed to bend a new receiver. This one bent as good as it could have, and I proceeded building. Once I had it all welded up and ready to drop the BCG in, it didn't fit. At this point I was over it and didn't want to invest anymore time or money into this heavy antiquated rifle that wouldn't offer anything one of my AR15's already did.

TL-DR, I have well over $1k into an unfinished rifle that doesn't work and is sitting on a shelf in my garage. This is one of those times I wish I would have bought an off the shelf rifle and had been done with it.

Come to think of it, I should demill it and sell it as a kit to try and get a few bucks out of it. Make me an offer? [wink]
 
Roller locked flats are tough to work with if you don’t have the proper tools. Even “experts” have difficulty making a functional gun.

This is something I've heard a lot, and it seems to make a LOT of sense (an AK receiver is relatively square and doesn't have much riding along it, where this is nearly round and coming from a flat piece). Thankfully I've got a serialized receiver/upper which came from a functional firearm, so that would not be a worry in my case. My biggest concern would likely be the trunnion, and getting it in place such that the spacing is appropriate and the rails line up properly.


I bought a complete Omega upper from Atlantic firearms, waited on my stamp, then pieced a lower/fire control group together (easy). Honestly the most fun gun I've ever shot. I go through far too much 9mm with it.

Did the upper have the trunnion/barrel in place? If not, was it challenging to get it right?
 
It was complete:
Omega 9mm K Style Barreled Receiver

Really just plug and play here. It would be a stretch to call it a build.

Ah OK "just add a lower" type deal. Not bad... pricing is... pricing. Which sticks out to me. Looks like pretty sweet build fodder, though. Good shooter?

I'm still waffling on whether to build this up or pass it along. Looks like the hardest bit is done (it's not a "flat") but that trunnion worries me, and a $1300 MP5 demill kit is a bigger investment than a $300 AK demill kit. Mostly because I really don't have any special desire for such a weapon beyond maybe being a sear host down the line.
 
Ah OK "just add a lower" type deal. Not bad... pricing is... pricing. Which sticks out to me. Looks like pretty sweet build fodder, though. Good shooter?

I'm still waffling on whether to build this up or pass it along. Looks like the hardest bit is done (it's not a "flat") but that trunnion worries me, and a $1300 MP5 demill kit is a bigger investment than a $300 AK demill kit. Mostly because I really don't have any special desire for such a weapon beyond maybe being a sear host down the line.

It's the MOST fun gun I've ever shot. It see's more range time than anything else I have. Something about the 9mm and the roller lock makes this buttery smooth and just a joy to shoot. Nice conversation peice/head turner as well. Get's tons of attention at the range. My all-in build price was right around 2k, which included a stamp, 2 different stocks, a fire control group and a handful of magazines. Worth every penny.
 
CETMEs are the cheapest roller kits, aside from MG42. MG42 is actually not a bad build and you get a kick ass beltfed you can keep around your living room next to your m40 helmet.

1200 isn't all that much for a kit, there are many far more expensive and the key is not to F them up of course.
 
CETMEs are the cheapest roller kits, aside from MG42. MG42 is actually not a bad build and you get a kick ass beltfed you can keep around your living room next to your m40 helmet.

1200 isn't all that much for a kit, there are many far more expensive and the key is not to F them up of course.

If I had a CETME or G3-style receiver I'd be all over it; those kits are dirt cheap and I've serviced many G3 clones and C308s at work.

Still waffling, but I appreciate the input. All said that's not a bad price compared to a complete firearm (9mm MP5 clone).
 
This is something I've heard a lot, and it seems to make a LOT of sense (an AK receiver is relatively square and doesn't have much riding along it, where this is nearly round and coming from a flat piece). Thankfully I've got a serialized receiver/upper which came from a functional firearm, so that would not be a worry in my case. My biggest concern would likely be the trunnion, and getting it in place such that the spacing is appropriate and the rails line up properly.

I built an HK94/MP5 clone without the use of a jig or press. I used a 3/4" rod, a block of wood with a groove cut into it and my vise to form the flat.
 
If you are handy it isn't that hard. the biggest thing is setting the bolt gap correctly (there is no real headspace with roller locked guns) when you press the barrel into the trunnion. other than that it is just normal fitting and metal work. But to be clear it is NOT an Ar type build. DO your research to learn the right way to do it and you will have minimal issues. (If they say headspace ignore the rest of the posting article, they don't know what they are talking about. )
(and I am the first non-ffl to build a working semi Cetme L)
 
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