Have been trying to make an M14 look more Carbine/G43-ish and wanted shorter mags.
Warren sells the converted shotty mags but I wanted a mag that was visible for this particular project, so ................
Top - before , Bottom - after
As far as I'm aware, this will only work with TM mags, due to the construction.
* Removed metal case from mag
* Removed spring
* Fortunately, the mag has a fretwork of strengthening moulds, and these can be carefully cut down to give a straight edge, so middle sawn through, to remove approx 50mm, and top and bottom glued back together.
*Metal casing cut down to fit new length mag (yet to do)
{ It was a lot more fiddly than that ^ sounds 
}
Mag is now pretty close to the 'correct' length for a G43 mag, holds 40-45 bb's, which should be more than enough for a single shot rifle, feeding is good, and the completed mag will fit in the repro G43 pouches with no problem ................. In the words of Paddy McGuinness - 'That'll do for me !' 
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Terms & Conditions of Sales :
Payment by Paypal only > Cleared funds must be available when deal is agreed - no e-Cheques.
Possible Swaps/Parts-Exs (with regular forum members only) -
* British BD Trousers & Blouse, to fit 48"-50" chest, 40"+ waist, tall fitting/long leg
* British Gaiters/Anklets, not blanco'd, largest size available
In situ, no metal casing as yet ...............
and the real thing ............
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Terms & Conditions of Sales :
Payment by Paypal only > Cleared funds must be available when deal is agreed - no e-Cheques.
Possible Swaps/Parts-Exs (with regular forum members only) -
* British BD Trousers & Blouse, to fit 48"-50" chest, 40"+ waist, tall fitting/long leg
* British Gaiters/Anklets, not blanco'd, largest size available
Yes, just trim the 50mm or so from the top, file in a cut out front and back, drill a small hole side-to-side for the locking pin and job done
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Terms & Conditions of Sales :
Payment by Paypal only > Cleared funds must be available when deal is agreed - no e-Cheques.
Possible Swaps/Parts-Exs (with regular forum members only) -
* British BD Trousers & Blouse, to fit 48"-50" chest, 40"+ waist, tall fitting/long leg
* British Gaiters/Anklets, not blanco'd, largest size available