Hi all, I snagged an Olympic Arms complete 9mm upper at my local gun show. A1 upper, weighted bolt, 16" heavy barrel. It's in pretty good shape, and I'd like to run it on a dedicated lower receiver. I'm guessing its from sometime during the 1980's, there are minimal markings to narrow it down. From what I understand, this was designed to take Sten magazines via adapter, or modified magazines.

I have a couple questions for those who own one of these, or have experience with them.

Backup plan is to use the drop in Hahn block. Any experiences using the Hahn sten adapter with unmodded / minimal modification mags? Reliability?

I'd prefer to use it with Colt / Uzi magazines. It might be a long shot - anyone run one of these like that? Preferably set up like the Colt mag well. If it's even possible, I'd like to pin the adapter in a dedicated milspec lower. The design of this upper predates the Colt design - wire ejector rod built into upper, instead of a fixed ejector on the lower. Not sure if compatible with the Colt or Uzi mags in general.

Lastly, anyone use Glock mags? My last choice, but if it's a viable option, I'm open to it. If Colt / Uzi mags are off the table, I lean towards this over the sten mag adapter per original design intent.

You might be looking for this style.  

Sten with Spacer welded

Plastic 9mm Oly Arms Mag

I remember seeing these around in the late 1980's early 1990's at gun shows.  

Check the bolt, as I recall it only being able to strip from a single column.

I think you're right. It does have a conical bolt shape.

https://www.at3tactical.com/products/sylvan-arms-ar-15-to-9mm-glock-conversion-block-gcb100

Would it be possible to use something like this?

I don’t know what it would take to make it work.  Isn’t the ejector in some odd place on those?
Probably a money pit, you buy one part, then another and another.

You know, I think you're probably right. Met my fair share of so called money pits.

I think I'll stick to the Hahn adapter with a PSA stealth lower and call it a day. Hahn adapter is just about the only known compatible device for this. Not much info on these.

The ejector is a spring steel wire, attached to a cross pin in the upper receiver.  It protrudes forward on the right side of the bolts path. It flexes under the bolt during cycling

Thanks

For what it’s worth, I have had a Hahn adapter running colt mags pretty much since Hahn came out with them.  Mine works well.
Colt mags are a pain to load, I use a Lula.  If you drop a loaded colt mag just right, you get a spectacular fountain of ammo.  
Probably why the Glock mags are popular.

I did have to adjust the ejector on my Hahn block just a touch, just used pliers.  Once you get yours built you’ll see what I mean.

I have one of these I bought in the early 2000s.  I have one of the welded sten mags.

I bought some plain sten mags to use with an adapter, but never could figure out what one to use.

It ran pretty good with the welded mag.  Sits in the safe now..,

I had one. I used the Hahn block that used unmodified Sten mags. When I had mine, the only choices were the Colt-style with modified Uzi mags, and the Oly-style that used Sten mags. No Glock mags yet. It worked well enough. The paddle mag catch was the biggest thing to get used to. It’s vintage, enjoy. Not sure how common Sten mags are anymore.

Thanks. I have the Hahn adapter on the way. One of my buddies has a few sten mags for me. I hope it runs good

Let me know how it works!

I wonder if they would loan you one for testing and evaluation.  It could open a very limited market for their product.

That is exactly what I was looking at. All of the other adapters do not look compatible. That one appears not only high quality, but it positions the magazine directly behind the breech. Glock mags are promising too, they're single feed, available, reliable, and good capacity.

I have the Hahn sten adapter on the way. I'd like to have a functional firearm before experimenting. I will definitely look into the sylvan adapter, and good point, maybe they have a blem return they could possibly loan me. If not, I'll buy one, I dont care. I'd imagine the adapter mounted ejector will likely need to be removed.

Once I try it, whether it works or not, I will 100% do a write up for "I just bought this strange 9mm upper" posterity. And the Hahn too, for that matter.

I had one bought new from Olyarms back in the 90's. Sold it shortly thereafter when I was younger and needed $. Yes, used modified Sten magazines with mag block provided by them. I hated that accidentally hitting the AR mag release button dropped the mag block out along with the magazine.

Pretty much says it for my experience, too.  Zero issues with the Hahn adaptor and colt style magazines.  And that lula loader make is so easy to get those last 8 or 10 rounds into a 32 round magazine.

My Hahn block loaded from the top, there was a small finger that sat on the top of the mag well that kept if from falling through. The standard mag release buttom locked it all in place. My RRA receiver was especially tight, so that helped lock it all in place. I think Hahn made both styles of block.

I’m glad you could find the sten block, can’t be many of of those around.

New production. Drops in from the top, no worries with ejecting it on accident. If that's my permanent solution, I'll definitely install some kind of california mag release thing to essentially delete it.

Working on a sylvan adapter. Not wanting to pay MSRP for a maybe.

For those who use the other hahn adapters, update, this upper is different from anything colt, or colt magazines, in terms of AR9.