the NTSC does not contain copy protection like most PAL region games have (most not all though, im not really sure if MGS does or not although it is likely). you should try making an image of the disc in either .bin/.cue, .ccd/.img/.sub, or .mdf/.mds. and you might have to mount the image onto a virtual driver afterwards (it doesnt need to be done in every case so you might not need to do it here).
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