I have a lot of Sten mags and want to try to use them in a 9mm AR setup on both pistol and registered SBR lowers (so no dedicated lower).  I have a hybrid-type bolt I'm working with now, so if I just can't get the Sten setup to work, I can fall back on either other pattern (Colt or dedicated Glock).

The Sten blocks are designed for the Olympic Arms-pattern 9mm which uses an upper with the ejector installed on a cross-pin.  Rather than do that, it looks like it should be fairly simple to add an ejector to the Sten block itself.  I did some measuring and eyeballing and it seems like something could be added to the TOP of the Sten block to be the ejector (modified/shaped piece of angle-iron steel screwed on top), or a slot could be added to the side to have an ejector stick up and forward, much like the ejector on the Colt-style mag block.

Has anyone done this already?  I've done some searching (Google) and have seen a lot of talk about Sten mags, but not really on this subject.

Thoughts or experiences?

Rob

It has been done. Not much call or need for it since the mag ban sunset.

Need to use a Glock-cut bolt with single-feed sten mags, and adjust the feed ramp for its presentation angle.

Threads are locked deep in the archives ca 2002-2003. "Colt pattern mag block for sten magazines" is the thread title I seem to be remembering.

I have already tested that the Sten mags feed from the mag and into the chamber nicely using the KVP "hybrid" bolt (designed to feed from both center-feed Glock mags and Colt staggered-feed mags), an old SOCOM mag block and a standard Sten mag.  I thought I had conveyed that.

Of course without an ejector, that casing/cartridge/dummy round just rides back and forth stuck on the bolt face (held in place by the extractor).

It seems simple enough to add an ejector to my block, either on top (with an "L" shaped piece) or in a slot on the side like the Colt-style blocks.  I was merely asking if anyone around here still had actually DONE it.

As for why...  I have more than 20 Sten mags (and a semi-auto Sten) and a mag block I got cheap.  With that, why would I buy a Colt-style block ($60 - 200 depending on brand and quality) and a bunch of Colt-style stick mags for at LEAST $20 each).  And tinkering is fun.  If it fails, THEN I can go the easy but expensive route.


Rob

Will do, when I have a minute.  I have done some measuring already, like finding center, how far off center the ejector should be, how high it can be max, etc.

Rob

The mag block from the left side (note the slot for the AR's mag catch).



Installed in the lower.  Note that it just a hair above flush...a couple thousandths max (probably supposed to be flush but a tiny bit above due to tolerances).



My sketch of the block and a thought about an ejector made from angle-channel steel and bolted to the top of the block.



Top sketch is the cross-section looking up from the bottom.  Middle sketch is the top of the block looking down (shaded area is curved downards).  Bottom sketch is looking at the front face of the block (where the sten mag would rest) toward the back of the gun and also shows a cross-section of the 9mm bolt as it rides above the block.

Rob

Sell the Sten mags and switch to Metalforms.  You will have a better outcome.  

The biggest reason is because the Sten mags are a motherfucker to fill.  Metalforms have a Maglula that fits and they load extremely fast. 

Old AR15 archive about Colt style mag block modified to work with Sten mags...

This was done before the 1994 AWB was allowed to die in 2004....  It was the 2 peice Colt sytle mag well adapter that was modified.  It worked good when I had it running.  With the AWB and mag limit gone, I went to a Colt style mag well adapter.  Granted, I still had issues with mags and this single piece Colt adapter.....

PS, the Quarterbore site, just tried, is no longer up .... and if it is.... I couldn't find it.  It had the how to instructions up there...

Not really.... take a dowel, push follower down... stick an allen wrench into hole to hold down follower.... load mag... remove allen wrench.  It has been a while since I did that..........

Been thinking of permanently mounting my old "Sten mag well adapter in a Colt style 9mm upper" to a lower.  Why not.  Somewhere I have probably 20 Sten mags, granted, I would have to notch them for Colt style mag release..... projects..... more projects then time.... and $$$

That mag block is intended for use with Olympic-pattern 9mm uppers, not Colt-pattern. That mag block locates the magazine flush with the front of the magwell, leaving no room for a feedramp, which on the Colt-pattern is mounted to the front half of the magazine block. The Colt-pattern barrel does not have an integral feedramp like the Oly-pattern does.

Thanks to @Kaliburz for locating and linking the thread I spoke about in Post #4.

Sten mags in a Colt 9mm system thread

Not sure if the pics in the thread will work....  has been a LONG time .... over 13 years....

No problem....

The last week, I actually ran into a Ziplock bag that had 3 sets of these modified 2 piece blocks.  Bought them YEARS ago from someone- don't recall if it was someone here or from Gunbroker.  A few of us here on AR15 did the initial RnD.... I built a prototype, Gloftoe did one too if I recall, a few others.  There was a "how to" write up made that a bunch of people requested years ago.... even went as far as talking to an expert.  From what I recall, they thought it wasn't feasible since Sten mags had a large variation in tolerances.  One of the small AR manufacturers even tested the block I made, they showed it to their expert machinist (who makes quality stuff, mind you.  I just won't mention names).... and the two mags modified.  It ran, ran great.... just never made it to production.  I call it a foot note in history....   I can't claim we were the first.  I am sure someone may have tried it but never shared...  lotta that going on before the internet got popular.

I went out to go look for said blocks and lol, can't recall where I moved them to (my gun stuff drawers/storage is FULL).  I was gonna take some pics and try to share.  I found two of the notched Sten mags I used.  I don't recall where I had my prototype.... like I said, after the 2004 sun set, the idea of using Stens in a Colt pattern died since new mags were being allowed.

If I find it, I will takes pics and see if I can get them on here.  I have not did pic sharing on the "new" site (I think this is actually the 3rd variation of AR15.com site software.....maybe 4th.. )

I was thinking..... (dangerous)

A billet could be machined to accept Sten mags (which has been done).  But all one had to do is position it correctly and install a feed ramp and ejector for the Colt pattern.

One could get rid of the Colt style mag release completely....the paddle style could be put on the bottom if the mag well is long enough.  I'm just thinking quick on the go....

Now that I'm thinking, I recall that I filed down the center of the ramp to a small V to feed better.  The adapter I modifed, it was kinda notched left/right since Colt mags are double feed (feeds from left and right) while Stens feed from the center.


Edit- Anyone recall when STEN mags were being sold CHEAP.... I think they were like $5.00 each..... heck, they were so plentiful, surplus places were selling them in package deals cheaper then $3.00 each.....  Somewhere I have at least 10... maybe more.  (Wasn't there a Mac type gun that used Sten mags......)

I bought about 100 still in original greasepaper wrapping for $2 each plus shipping. Still have them and they're still wrapped. The stainless steel ones are nice, too - those were more like $10 each.

I've got an M10 with interchangeable magwells for sten mags, uzi mags and cobray mags, and use them with my sten and my M16 with magblock and Oly-pattern upper.

A grease gun mag loader can be used on Sten mags. Has a little slop side to side but it works.

You can also shoot 185gr HP .45 rounds out of Sten mags.

Back on topic...

@Mad-Machinist  Did you get a chance to look at my pics and sketch of one idea I had about adding an ejector to the TOP of the Sten block?  This would be easier to make without a machine shop as it would only require a grinder and drill press.

The other idea is to slot the back and use a replacement ejector for a Colt-style block.  I actually bought 2 from RRA to check out.  Drawback is that milling a slot for the ejector is more difficult.  The only mill I have is a micro-mill attachment for my micro lathe.

BTW...the first pattern British military loader for the Sten mags works quite well.  It is the one with a brass or bronze thumb ring and it snaps onto the mag and you just rock it back and forth to depress the follower, drop in a round, then push it back.  Pretty neat.  IMA sells a reproduction, but originals are available and reportedly work better.  Sten loader



Rob

I've done it.

I designed and made my own magwell insert for Sten mags, and added an ejector. I used a CMMG MK9 replacement part which was ~$12 and only had to drill a hole (I reamed it too) and used a setscrew to lock it in once adjusted. Works amazingly well. I too wanted to use a standard receiver (not OLY) because I had Sten mags.

THIS



Never posted pics here and I don't have photosucket, but maybe I'll try to figure it out if anyone cares enough.

Attempt at pics:
Doing layout


Before drilling for ejector and making slot for mag catch.


Ejector as it rides on bolt


If I were to do it again, I would offset the location of the ejector as opposed to bending it. I thought I wanted the mounted portion centered on the block, but that wasn't necessary. Custom skeletonized receiver set there in case anyone is WTF'ing at the pics.

Note, there is also a 'wedge' insert at the front of the magwell so the mag sits at a 5° angle which aids feeding round and flat nose without needing a feed ramp. I machine the Sten mags with a slot (similar to Uzi conversion process, but with a slight angle) so standard AR mag-catch works.

Attempt at pics:
Doing layout


Before drilling for ejector and making slot for mag catch.


Ejector as it rides on bolt


ETA: Tried to make them hot for you, but was not successful, as far as I can see. Your pirate4x4 account may not allow direct reposting from your gallery or something like that. Try imgur.

Thanks. Hows that? I'm able to view them (was before as well) but that may not mean anything!

Thank you!  I'm going for the same effect with a slightly different approach.

Have you had any trouble with wear or breakage of your ejector?  If so, is it pretty easy to replace?


Rob

I'm only in about 100rounds so far, but no issues. Literally just finished the gun last week (posted in the picture thread). It is VERY easy to replace. One setscrew locks in the assembly. I cut down a roll-pin to hold the ejector part into the round insert. Round insert drops into the block and this allows about 0.200" adjustment up and down which helped get it in the right position relative to the bolt groove. The 'problem' would be re-creating the bend. Doable as I did this one and it's not rocket science, but a new ejector wouldn't be immediately drop in.

This is another reason that on MKII I would offset the ejector in the block as opposed to the ejector body being centered on the block and the ejector bent as shown. I created more work for myself on the first iteration! I may make another one as a spare or to fix these quirks.

Working fine now - nice job. You took the classic Colt-pattern magwell adapter approach, and angled the magazine inside the blocks to compensate for the lack of a feed ramp.

You're still going to have issues with feeding I think, trying to use your Oly-pattern sten magwell adapter, unless you angle the magazine somehow like LilBucket, or shave the magwell adapter to move the magazine seating position further back and provide a front insert with a feedramp.

Ed Zachary.

You can see the front 'wedge'. It's held in with a small button head machine screw in the front of the magwell.

Best view I have of it at the moment


I went a bit "overboard" , but it has paid off




Straight inserted mag and the mag moved back with a feedramp was plan B. You can get a CMMG feedramp too. Still would need a way to capture each block in there. Angled setscrews would work in a standard (non-skeletonized) magwell a -a the new Torkmag, but I had other options with my design.
HERE

I just looked at the photos in the pic thread. Looks great. Just curious about the skeletonized upper. Do you get lube flung out of the openings? I'm curious what it would be like with a can on it.

With the Oly system and their type of mag adapter, the Sten mag is flush up against the front of the magwell and feeds straight in.  Doesn't need a feedramp or anything.  All reports I've read say that the system is reliable "as is".  That's what I'm shooting for.  In hand cycling the bolt slowly, the rounds fed right in for me (using an upper that is NOT an Oly).  

My upper assembly is an Aero slick-side upper, Ballistic Advantage 8.3" barrel & KVP ramped hybrid BCG (Glock or Colt).


Rob

Thanks! Designed and shown with can on it. No lube gets flung nor gas in the face. I use Froglube so that may be part of it, but any excess lube that could or would get flung is probably gone by the first round anyways. The F1 Firearms version had good reviews in all regards and I opted to not go so far forward with the slots on the left side of the upper JIC.

I heard (read) somewhere that someone did some slow motion analysis and determined the feedramp wasn't even being contacted in one of the major magwell versions, hence removal of it from the design. In my case, the angle was primarily to consider different bullets (flat nose and HP) as it seemed safe to assume round nose would feed themselves. In early R&D - head and ass scratching while hand cycling - I was seeing some flat nose rounds either dead heading against bottom of the chamber, or flipping backwards and not going in. The 5° solved this entirely.

Having said that, if you're at the front of the magwell and the mag is sitting high enough, you may achieve the same results with the bullets pointing almost directly into the chamber. You may have to mill flat or shorten the original Sten mag 'stops' to get them to go a bit deeper if need be.

These are all my musings and findings to get to where I am so it may be hogwash, but maybe useful somehow!

Not quite. The oly system has a feedramp integrated into their barrel extension. The oly barrel does not sit flush with front of the magwell, and there's an actual bolt inserted into the oly carrier - although it's pinned in place and does not cam.

I bet the slots would vent the gas out well. I never tried frog lube. Is it thick? Great machine work all over. I like all the details with the flag and statue of liberty.

Thanks

Yes, it's much thicker than regular oil.

The slots on the left side are farther back then the ejection port opening on the left so my "theory" is that the majority, if not all, of the gas blows out that side before it gets to my slots on the left side.

idk. It works. Maybe one day I'll get some high speed video of it .

There are two mag loaders made specifically for Sten.  I have also used the dowel rod method, with the dowel in a drill press.  

The ease at which the Maglula loads up a Colt mag is priceless by comparison, and it also unloads them.  Anyone who hasn't tried one must do so.  You can probably load the Colt mags by hand.  Your fingers would be hamburger after trying that with a Sten. 

I used Sten mags for 9mm, over 15K rounds worth, enough for a broken extractor and hammer pin on my Oly.  I also modded Sten mags and used them for .45acp 230RN.  

I hogged out a UpLula for grease gun mags.  Works amazingly well.