decided this may help people with the airsoft thompson and g and p conversion. Im sure many of you as i did had the mag that was too long to allow the bottom cover to be fitted once the mag was in position.
Now the alternative is get lucky and locate a cheap 190 mag, or pay around 30-40 quid delivered brand new.
or
mod the long one for free and have it still capable of working, so heres how to mod the long mag, approx time is less than 1 hour of your time:
this is the longer mag, it pokes out the bottom of the pulse rifle so its very annoying:

this is the bottom of the mag, you need to slide out the clip by prising with a flat bladed screw driver and then it will simply slide out:


next locate the 2 pins on the mag and push them with a small screwdriver, they will push out the other side allowing you to pull them out with pliers:


now your able to slide out the inner workings of the magazine:

unscrew the highlighted areas:

and disconnect into 3 parts - you will see the clip to push and it releases the parts, take the middle section and put it aside (you no longer need that bit):

fix the bottom and top plastic parts togeather, snap them togeather and re insert the screw:


next measure the mag internals - i got approx 154mm, you will need to drememl the metal mag down and still be able to re insert the internal mag workings so accuracy is a must, placing the internals in position and using the pin aligning holes you will be able to see the postion to work out what needs removing:

i worked out i had to remove around 60mm of the bottom of the metal mag - again triple check your measurements:

you also need to mark out some tabs so you can fold them over the bottom just as an extra precaution to keep the internals solid:

the highlighted areas show the tabs you need to make on both sides:


now take the dremel, the cutting disc and cut away:




once dremeled you will also need to remove this highlighted area now is more acessable to get the disc in on one side of the mag:



one side done and tabs done:

once all the tabs are done and dremelling is complete, insert the plastic internals and you will get this:

place the pins back into the mag and push all the way through to hold the mags internals to the metal casing:


you will now be here:

start folding the tabs back with pliers:


and test fit the mag, you will notice there isnt much to grab so the tabs we have not yet touched will used next:


fold down the remaining tab so that only the sliding tab on the mag remains straight, and then drill a hole in that part as pictured:


insert a heavy duty ish cable tie so your able to put your finger in and grab the handle thats just been created. this will allow you to pull on the mag whilst releasing the lever to pull it out. the cable tie will swing the opposite way and be hidden when the cover is fitted:


re insert the casing into its location and thats it, all done:

load up the bb's and fire one off, everything works fine, access to the winder is still available just like it was beofre it was modded:

i know its a little crude, but its cheaper than paying for a new mag and saves the long one simply rotting away pointlessly.