I've just ordered a sten mag block from SNS industries so I need to notch some mags.  Does anyone know exactly where to notch them?  I'd like to eliminate as much trial and error messing around as possible.  I also noticed that some people (SNS) have shortened sten mags to 20 rds.  Does anyone have experience with this?  If so can you provide me with measurements/directions?

Quoted: I've just ordered a sten mag block from SNS industries so I need to notch some mags.  Does anyone know exactly where to notch them?  I'd like to eliminate as much trial and error messing around as possible.  I also noticed that some people (SNS) have shortened sten mags to 20 rds.  Does anyone have experience with this?  If so can you provide me with measurements/directions?

Quarterbore is a member here and has some instructions on his website.
www.quarterbore.com/ar15m16/colt2stenmags.html

The shortened magazines are made by cutting them down, and reshaping the bottom so you can replace floorplate.  It more of a trial and error.

I realize the shorter mag is made by cutting it down and reshaping.  What I'm asking is if anyone has experience with this modification and what were the final measurements.  I just want to have a good starting point so that I can eliminate most of the trial and error.  Sten mags aren't nearly as cheap up here in Canada so I'd like to butcher as few as possible.

Quoted: I realize the shorter mag is made by cutting it down and reshaping.  What I'm asking is if anyone has experience with this modification and what were the final measurements.  I just want to have a good starting point so that I can eliminate most of the trial and error.  Sten mags aren't nearly as cheap up here in Canada so I'd like to butcher as few as possible.

Member  "PAPPYO"  is the man for the 20 round Sten mags.. he done so many, he probably do them with his eyes closed.

Do a search for PAPPYO, as reply authors in the last 3 month.. from there, use his "user info" and e-mail him, as he has not been around for a while, but recently posted here in the last 2 weeks.

email ---> www.ar15.com/member/mail.html?id=1539

"IM" ---> www.ar15.com/messenger/sendMessage.html?uid=PAPPYO

Thanks for the tip SBR7_11

Question from the uninformed: why would you want to reduce capacity to 20 rounds? A legal requirement or some type of functional improvement?

Quoted: Question from the uninformed: why would you want to reduce capacity to 20 rounds? A legal requirement or some type of functional improvement?

The Sten Mags are kinda long

I think the idea is just to make them more compact

Question from the uninformed: why would you want to reduce capacity to 20 rounds? A legal requirement or some type of functional improvement?

I like to have a couple just in case I want to shoot off a bench or sight in.

I just think that the 20 rounders look more balanced in a 9mm AR SBR.  Up in Canada we have to limit our mags to only hold 5 rounds so I'm not really losing anything, just making them more compact and better looking (in my opinion).  FYI India did modify their mags to 20 rds for reliability reasons but they didn't alter the body, they simply welded in brass rods on one side to turn it into single stack.

Leg,
    Did you ever find the info you were looking for?

Not yet, I haven't received a response from my IM so I'll try e-mailing him today and see if it that works.

This may help -- I made 20 round mags out of the sten's years ago and took pictures. You will need a Dremel tool to do some cuts and make the tabs on the bottom. These mags were made to work in a Colt system that had a modified magblock for sten mags.

This kinda gives you an idea on the final mag body length and the spring length. Please note that you will need to play with the spring length since they all seem to be a little differnt.


This is how the tabs are made. I measured up from the mag bottom around 2.0" to 2.25" and marked with a line. I cut the bottom of the mag off about a 0.25"down from that line. I cut out the sections in the front and rear, just below the line I drew, with a dremel. I put the tabs in a vise and bent them 90 degrees. Then I slowly started to cut the tabs shorter, using the original mag bottom as a guide, till I could get the bottom plate to slide on. Please disregard the spring length in the lower pictures and the marks on the mag --  I was making a very short magazine but I wanted to show you how the tabs were made..


I hope this helps if you don't get any other info.

AR-fan, Very informative, this will be a big help.  I shouldn't have too many problems now.

Thanks, Sam

20 rd Sten mags can be found. LongBranch made 1Mil of them. Yes, the 32rd is more common. Do an off topic post on one of the Enfield foroms and you'll find some.
Can I ship Sten mags to Can.?
ATB,
Chalmers

Shipping mags shouldn't be a problem.  I'd have to check and see if the US requires an export permit for those kind of mags.  The mags do have to be limited to five rounds though, prior to them coming into Canada.  I didn't realize that Longbranch had made any shorter mags.

Well, I thought www.Marstar.ca would have the mags. Just fell over when I saw the price 28.95/34.95(used/new) even in beaver bucks thats high.
One could always just buy the mag body(replacement part...) from the states and do your own mods. If its a pistol it can have 10 rds heI buy parts from Canada all the time. U.S. import law, less then $100. in parts needs no paper(well not assault barrels).
Good luck!
ATB
Chalmers

Yep, mags aren't cheap up here.  You'd think that Sten mags would be dirt cheap seeing as how we made tons of them.  I found out that the States does require export papers for mags, but that's not much of problem.  The problem is finding 20 round mags or bodies.  I've done a web search and all I can find are the 32's.  Does anyone know of source for the 20's?

Leg,
    Northridge International has 20 round mags -- actually they have two types. I think one is a like-new mag at $20 (ouch) and the other is probably the standard used magazine for $7.95.

Here is the Northridge page, the sten mags are all the way down on the bottom; northridgeinc.com/sp_mags.htm

I can't say for sure but these may be the sten mags made for use in India and are the same length as the 32 round mags but give Northridge a call -- the 800 number is at the top of the page.
If you don't want to call then here is the "Contact Us" page with their e-mail address; northridgeinc.com/contactus.htm