For reliability purposes, I'd recommend you install a bullet guide.Just got the mags today. I compared the feed lips and front of the magazine. they are slightly different. In operation they feed just fine. the magazine itself requires no mods, no feed ramp is needed.
Dinzag (probably the best known purveyor of such parts) offers bullet guides that are attached with a screw.I know this might be a stupid question but why drilling and tapping to install the bullet guide? Doesn't it rivet in place?