Sten Magazine Repair Tools

[tj214]

You were super lucky to find the mandrel, so congrats! That part has been unobtainium for years.

The hammer (the part you need) occasionally shows up (without the mandrel) on various gun parts selling sites, so your best bet might be to check everybody who sells (or used to sell) Sten parts to see if they have one laying around, or are willing to put you on a wait list.

Fabricating one will be a challenge, not least because it's not clear only one design was used. I have two hammers and they have distinctly different cutout depths and widths. Which one is "correct" turns out, at least for me, to be irrelevant as I find one is useful on some manufacturer's mags and the other on different manufacturer's mags. Since so many mags are unmarked it's difficult to predict which is which.

Also note the hammers are produced from a single piece of steel, which requires a mill and lathe. Presumably welding could lead to shaft/head separation in use. Also note it's hardened steel, so presumably the designers took metal dimensional changes due to hardening into account when the plans were drawn up (or probably not; this is for a Sten, after all...).

Finally, you really need to have (read: must) a magazine angle gauge to check your pounding on the mag lips actually seats the top round at the correct angle. Marstar in Canada used to have some, albeit at an astronomical price. I've heard some guys just use a protractor, but since I have the gauge I use it. If you get the angle wrong you can end up chasing the problem for a long time. The ultimate proof is whether your gun reliably feeds from the whole mag.

Oh, and finally finally, except in the extremely unlikely case somebody modified it, your mandrel will not work with a 20-round mag (the ones modified with the four brass rods inside to create a single rather than double stack of cartridges).

There are tons of mags that have had the brass rods removed, and the mandel/hammer will work OK for them. But before you go removing the brass rods (they usually cannot be reinstalled), make sure your gun works OK with the double stack or prefers the single stack (which is why the single stack was invented in the first place).

This is my experience from fixing several score mags. Your mileage may vary.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[StrangeRanger]

I bought a gauge from BRP which is why I knew I needed the tools. None of the US sources that I tried had any so I tried Marstar. They had one mandrel left but no hammers. I bought what I could. I think I may be able to improve if not exactly fix my mags with the mandrel and a ball peen hammer but I'd really like to score the correct hammer.

I had no idea that there were multiple versions of the tool set. I guess I'm getting bitten on the arse by the Brits penchant for small workshops. Where was Seymour when the Brits needed them

[tj214]

Not sure I'd recommend a ball peen hammer. If you're going to forego the magazine hammer, might try starting with a hard, small head mallet, possibly very hard rubber or plastic. The feed lips are thin (and may have gotten thinner over time if people beat the crap out of them with a mandrel and magazine hammer) and not only bend, they break. Suggest starting "softer" and graduate to "harder" if the mallet doesn't get the job done.