I am building my toy now, and I am about to get teh mag block.  My question is which system to use.  I am laening towards the HY-Tech becasue it is simple, easily changed out, and uses quality mags that can be found in 10-20-25-32-and 40 round capacites.  Is there anything I have missed about the Sten system that would sway me towards that route.  Let me know what you guys think.  Thanks.

UZI mags can be loaded way faster than the Sten mags. IMHO the single best reason for the UZI mag route.....

who cares about the speed of loading the mag. buy a mag loader. Look at the price difference between the two. I'd rather save money so i buy more goodies for the AR

I have the Uzi system with a Hy-Tech block.
For me, its been the most reliable.

Where would a person get a Hy-Tech mag block.  I have an Oly 9mm upper and have been using modified Sten 32rd mags.  The Sten mags are new and tight and they don't load and feed well.  Any way to loosen these mags up???  For this reason, I'd like to try a different setup.

Quoted: Where would a person get a Hy-Tech mag block.  I have an Oly 9mm upper and have been using modified Sten 32rd mags.  The Sten mags are new and tight and they don't load and feed well.  Any way to loosen these mags up???  For this reason, I'd like to try a different setup.

The Hy-Tech block is for the Colt style 9mm set ups.  The Oly uses a different system and thus, you are stuck w/ using the modified (ie block welded to the back) Stens.  The only mag I've seen used in the Oly 9mm is the Sten mag.

The only two 9mm "feed patterns/styles" are the Colt style and the Olympic style.  Each is different.

Stens will always be "difficult" to load.  I suggest, as many will, that you invest in a loader to aid you.

Quoted: I am building my toy now, and I am about to get teh mag block.  My question is which system to use.  I am laening towards the HY-Tech becasue it is simple, easily changed out, and uses quality mags that can be found in 10-20-25-32-and 40 round capacites. Is there anything I have missed about the Sten system that would sway me towards that route.  Let me know what you guys think.  Thanks.

What do you want to know about the Sten mags in the Colt system?    More info on the Sten mag use in Colt 9mm setups  Take a look at that, if you have any more questions, post back.  That is a little more direct then reading the tack in the section.

Oly Arms offers modified Uzi mags on their website.  What mods are done on these to make them Oly compatable?  Is it simply the attached mag block or is there more than that to it?  Thanks for the info.

Sten mags are a pain to load, but for $4 a pop, I can live with it. Just get a mag loader:

Loading is the MINOR issue vs the FTF due to the tight mags that will not feed reliably.  I want mags that feed properly.

Quoted: Where would a person get a Hy-Tech mag block.  I have an Oly 9mm upper and have been using modified Sten 32rd mags.  The Sten mags are new and tight and they don't load and feed well.  Any way to loosen these mags up???  For this reason, I'd like to try a different setup.

Oly sells a mag loader and it works great, problem one solved.  Don't  load a full mag or load a mag to full capacity and leave it for a while to help with spring compression or remove your  spring and trim a little off of it, problem two solved

Quoted: Loading is the MINOR issue vs the FTF due to the tight mags that will not feed reliably.  I want mags that feed properly.

Tight mags??????  You mean the follower is getting stuck inside the mag body?  Have a ton of Stens and that has not been an issue w/ me.  Have you taken them apart  to see if the follower is bur free and moves up and down w/out any resistance?  Also, make sure the body of the mag is not dented, as that will affect the follower inside.  My experiace from Stens are, they feed great.  Better then some colt/uzi mags.

Quoted: Oly Arms offers modified Uzi mags on their website.  What mods are done on these to make them Oly compatable?  Is it simply the attached mag block or is there more than that to it?  Thanks for the info.

Yup, it's simply the block welded to the back w/ a notch so that the original AR mag catch works.

These mags are new and unused except for the one time I shot my 9mm upper.  Tight mags means they do not load to full capacity and when at, say mid twenty round range, you can hear rounds rattling loose in the mag, possibly meaning the mag block is cocking??  Never could get the full 32 in the mags.  Anyway, disassembly and cleaning are the next steps.  Thanks for that.  Loading the mags and letting them sit is next after the cleaning.  Thanks for all the help.

mongo,

I have a socom block for my oly, and use unmodified sten mags. It runs great. FTF's are rare, matter of fact they have only happened with dented mags.

If you're having problems, post more details, maybe we can help. Your oly should feed better than it does.

I really believe the FTF problems I have are mag related.  On each FTF, I draw back and lock the bolt, remove and tap the mag, then continue on.  At times I would recharge without removing the mag and a bullet would still not feed, upon further inspection, the bullets weren't being fed up the mag far enough, like the block in the mag was sticking, thus I started removing, tapping, reinstalling and going on.  Each of my four mags have 2-4 FTF for each load, which is only around the 28rd mark (as much as I can push into them).  I think the mags need to be disassembled, deburred/cleaned and lubed.  I am also going to get a loader and load to or near full capacity and let them sit for a while as well.

I will also be getting a SOCOM mag block and some unmodified Sten mags.  This upper is so much fun to shoot, I want it running well.

Thanks for all your help, it definitely was what I was looking for.

I've done both - I'm currently using the UZI mags, but its been more of a PITA than using sten mags.  If youre handy you can easily mod an UZI block(s) to use sten mags.

Sten mags are cheaper, softer steel so they are easier to cut the mag catch notch with hand tools and the feedlips on the ten or so I modified were right on.  Only down side is they are harder to load and they are longer (looks funny to me)

UZI mags cost more.  They are harder steel - = they can be a bitch to cut the mag notch in.  Of my 8 mags I had to tweek the feed lips to get they to feed correctly.  in the process I cracked one and the $12 mag was a loss.

If I was doing it again, I'd go with the modified Uzi blocks and use sten mags.  My set up is a RRA block with there upper and bolt.

It almost sounds like you've got some old sten mags that still have cosmoline inside the body causing the follower to drag.

I think Tapco is still selling sten mags for around $4 a pop in quantity. I'd try some new ones.

I've been playing with my mags and upper for the last three hours now.  I disassembled one and there was plenty of cosmoline in it (spring, follower and mag body).  I cleaned it out, lubed it and reassembled it.  It loads much better but still FTF about halfway through the mag (manually drawing back the bolt, locking it open and releasing it with the bolt release- repeat - trying to duplicate actual feed/bolt velocities as closely as possible).  It FTF about three to four rounds, then it clears up and feeds most of the rest of the mag OK with a couple of FTF here and there through a few more mag loads.  It always FTF at about the same spot, about halfway through.[scratcing my head]

BTW, these are not modified mags from Olympic, I bought them from a guy in an online auction.  He modified them himself by drilling tapping the rear strap on the Sten mag and made a block out of some type of plastic and bolted it on the mag.  I am starting to suspect the quality of this work.  It sure does appear to me that there is very little of the bolt exposed to the next round in the mag and ALL of my FTF are the bolt missing the rim of the bullet and catching the center of the cartridge (lengthwise) and cocking the round in the magwell/chamber area.   This leads me to believe that the mags may not be sitting high enough to expose enough of the cartridge rim to the bolt, not allowing the bolt to properly strip the next round out of the mag into the chamber.   I have a feeling that this is a major contributor to my FTF problem.

Luckily, I can still use these mags with the SOCOM mag adapter that is on the way, as the impact of his work was minimal and should not affect the mag block operation.

Figured I'd take it to the range next time and feed some live rounds through it to see how it goes.  Maybe the SOCOM mag block will be here by then.  Also must disassemble, clean, lube and reassemble the other three mags I have.

Thanks again for all the help.

Ahhhh....there's your problem. Homemade mag blocks bought from online auctions.


Oh, FWIW my oly don't cycle worth a flip manually. You have to actually shoot it to check it out, but I'm betting that cleaning the gook out of your magazines helped, and going to the socom block will help even more.

When you say that there's one specific time that the mag starts screwing up and then it's OK again, I start thinking that the home-made mods to the block may involve a screw or something that's too long and is protruding into the mag.  The follower will hang up as it's passing this obstruction and then be OK again once it gets past it.  That or a tight spot in the mag tube.

Look into the mag tube with a strong light (with it disassembled) and check for anything protruding into the interior of the mag.  If there is something, it will have to be filed or stoned down.  If there's a tight spot in the mag, the easiest way to resolve it is taking a bit off the follower where it's rubbing.  It's not easy to drive dents out of a mag body.  The follower should drop freely up and down in the mag tube under the force of gravity alone if you turn the mag tube upside down and right-side-up with just the follower in it.  If it hangs up anywhere- that's your problem.

No screws in the mag.  They are only long enough to go through the strap on the back.  Already looked at that.  After playing with the upper and mags for about four hours non-stop yesterday, my feeling is if the mags just sat a hair higher in the magwell, the whole FTF problem would go away.  I think the block made for the mag makes the mag sit too low in the magwell.

Will the follower fall freely if you turn the mag upside down and back up again? (No spring in it.)

Dedeye;

Yes.

Well, now you're running me out of ideas.  If the follower falls freely then it isn't binding.  Is this a stock Sten mag otherwise?  Can you compare it to an unaltered Sten mag?  The fact that you can't load it to full capacity suggests that the spring in the mag is too long and the previous owner (ot someone) put in a different spring.

I am currently trying to cure the identical problem with a couple of MAC M10/45 40-round mags.  The spring binds about half way through the mag and causes FTF.  You can press on the top round in the mag and feel the lack of tension on it, but when you get down to about 15 rounds in the mag the tension is back up to snuff and it feeds perfectly.  If your mags are standard-capacity Stens, then you should be able to fill them up with 32 rounds no problem (with a mag loader).  The springs in Sten mags are generally pretty gentle.

The only other thing I can think of is some burr or other restriction in the feed lips that prevent the top round from coming up into position.  If so, polishing that area will cure the problem.

If possible, try to find a stock Sten mag and compare the springs, followers, etc.  It sounds like something has been changed.

Quoted: It sure does appear to me that there is very little of the bolt exposed to the next round in the mag and ALL of my FTF are the bolt missing the rim of the bullet and catching the center of the cartridge (lengthwise) and cocking the round in the magwell/chamber area.   This leads me to believe that the mags may not be sitting high enough to expose enough of the cartridge rim to the bolt, not allowing the bolt to properly strip the next round out of the mag into the chamber.   I have a feeling that this is a major contributor to my FTF problem.

Aha!  I thought that was your problem right from the get-go.  The guy who made your mags put the integral mag block notch too high, therefore making the mag seat into the magwell too low.  From how you describe it, it is a matter of just a few thousandths of an inch.  Not sure how to address the problem right off the top of my head.  If it were the other way around--with the mag seating too high, you'd be able to take a bit off the top of the notch hole to make the mag seat lower.  But to make it seat higher, you're gonna have to move that integral block notch down to get the mag to seat higher.  Is it possible to to that?  

Another possibility is to open up the feed lips just a little bit, which will cause the 9mm rounds to sit higher up in the mags.  Don't open them up too much, as then the rounds won't stay in the mag at all.  STEN mag feed lips are robust, so you'll have to use some force to open them up.

Might just wanna go with the SOCOM block and unmodified STEN mags and keep those other mags as spares.  OR, you could go the route I went and re-invent the Oly Arms wheel like I did at this link HERE.

Whatever you decide, the problem with those mags is clear: they seat too low for reliable feeding.  

Now that I've thought about it a bit, being the adventure-lover, I'd open up those feed lips to get the 9mm round to seat higher.  A bit of a risk, but STEN mags are tough, and you only live once.  

BTW, someone mentioned the Tapco Sten mags.  I bought 20 of them and they had some rust and lots of cosmoline.  Here's what I did:

Brushed them in a solvent parts cleaner.

Sanded/filed the rusty areas.

Sprayed them with a couple cans of brake clean.

Pained them with engine enamel.

They are good as new!!!

Quoted: BTW, someone mentioned the Tapco Sten mags.  I bought 20 of them and they had some rust and lots of cosmoline.  Here's what I did: Brushed them in a solvent parts cleaner. Sanded/filed the rusty areas. Sprayed them with a couple cans of brake clean. Pained them with engine enamel. They are good as new!!!

Sounds like they turned out good!  Pic???

As for I, as long as they will feed, I don't care what mine look like.