A habit won't be forgotten in the heat of the moment, on the contrary, your brain will take over and it will be natural.
You can order a new carrier from Brownells and have C-Rums weld it, but you will create a failure to feed situation, that little cut-out is there to guide the shell. Go to the 3 gun forums and read up on the FTF on the M2 and many others, you will have to chamfer the chamber to prevent the shells from hanging up.
Chiseled out of stone
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