FTF with MK in Full Auto

[GMANINGA]

I have an MK 5 tube gun, and been having some issues with FTF when the mags start to get to the last 5-10 rounds .. it seems like there is a failure to extract, feed, the only way to clear it to remove the mag, rotate the gun to drop any shells , and reinsert the mag. I will say that all of the mags are from a bunch of “new” surplus mags, so perhaps weak springs could be an issue. Any guidance or ideas would be welcome.

Thank you in advance

 

[brenbuilds]

This is often a symptom of a weak magazine spring. As the spring decompresses, the positive pressure against the feed lips reduces and sloppy feeding and malfunctions become an issue. The standard length of a healthy STEN mag spring is 12.5 inches; you can use a ruler or measuring tape to check this. Below this benchmark you will begin to incur issues. New springs can be purchased for $3-$5 from places such as RTG.

If the gun was running fine prior to using this new assortment of magazines, then they are certainly suspect. If the gun was not running nominally prior to using these magazines, I suspect it is a magazine and extractor spring issue.

 

[GMANINGA]

@brenbuilds thanks for the tip! I just ordered new springs from RTG and a new spring kit too. I would guess since the springs could be 70-80 years old, they may need replacement. Thanks for the suggestion. I will replace all of the springs in the mags and gun too.

 

[pjm204]

Shameless plug. I have a TON of Sten mags I'm selling. 20 round Indian converted that I am selling in 5 and 10 packs in case you need any. Good luck either way!