I have a total of five Witness 10mm magazines.  I have a Witness and Elite Match, each came with a magazine.  I purchased an additional 3 pack of magazines from EAA.  The Elite Match magazine is different from the other four.  The other four required material be removed from the top of the magazine pad/base before they would work in the Elite Match.

First we have a picture of three magazine base pads face up (off the mags obviously).  The one in the middle came with the Elite Match (hereafter 'elite mag').  The other two are from the three pack (or perhaps one came with the Witness standard, I can't tell them apart anymore).  You can see the difference plainly.  It appears the elite mag was sanded on a sanding station.  The marks are very straight uniform.  The other two on the sides are more random since I sanded them by hand on a sanding block.  You will also note on the top of both a dark spot.  This is a low spot in the plastic.  It is most apparent in the mag on the right.


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These next four pictures will contrast how close the top of the magazine base fits to the bottom of the grip frame.  First two of the Elite Match frame.


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Notice how tight the magazine sits to the frame.  Contrast to the Witness standard below, with the same magazine.


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You can see the difference. Remember, this magazine fit reasonably tight to the base of the Witness before I altered it.  When I first tried to seat the magazine in the Elite Match, the slide was open, and it did seat and the magazine catch partially engaged.  Having read another post (not sure where) about magazines not properly engaging in some Witness pistols, I knew to suspect the base plate.  A little work it engaged properly.

Hope this helps.