Got bored today doing a SMLE rifle kit, so as I had another gearbox to do another quick change conversion on, I thought I would do another Thompson too.
Strip out g/box as normal, remember to look out for those pesky little spring detent heads when removing selector switches!
Tear down g/ box as normal. Clean of any grease.....completely.
Inside of the rear end of the g/box reveals where the spring guide sits, this is cut out nearly to the stepped part, here's a couple of pic's and of the tools I use.
After rough grinding out, smarten up with file, just enough taken away to let the spring run through, I then use a V3 spring guide as they have wider location tabs or "ears" on them, mark and cut out with file inline where the original guide was situated, I also cut a bit of piston guide rail away, so then the guide can be pushed in and turned.
Now, as the spring, whilst doing its bouncy bit, will turn also, I then make a retainer, to stop this, just a bit of shaped aluminium strip does the job, suitable sized washer, and bolt in the end all clamps up nicely.
When doing the Thompson, this conversion has to stay low in profile as there is not much room behind it, because of the rear sight adjustment box.
I have done a few of these conversions now, on V2, V3 and V6 g/ boxes, and had no disasters, have run my own conversions for more than 18 months, the AK test gun has taken a good hiding, running double speed with this conversion.....still going strong!
A few more pic's
Last few,
Andy
