1911 magazine feed lips.

[RickB]

I think, if memory serves me, the "wadcutter feed lips" allow the cartridge to be released from the magazine sooner, and the cartridge has a more straight feed into the chamber.

The waductter design holds the rear of the cartridge down as the round feeds forward, rather than allowing it to rise and straighten as with G.I. and hybrid designs; it might release sooner, but the rim is lower in the mag, and the cartridge angle more acute until it is released.
It might be a better design for very short, oddly shaped bullets, but most modern .45 bullets have essentially a hardball profile, even if they're flat- or hollow-point.

[KyJim]

The "Hybrid" feed lip design is Colt's. It came from the die and anvil that AMU armorers used to create a timed release point in the standard "Hardball" magazine lips to enable use with the H&G #68 bullet. Colt just took a page from them and started to specify the modification for their vendors because it also worked well with hollowpoints. I am, however, responsible for them offering the Wolff 11-pound spring in their 7-round magazines as an option.

I collaborated with Check Mate on the development of their bullnose follower and provided them with the dimensions for a gauge to check and set the final release on their full tapered GI reproduction magazines.

Thanks for setting the record straight. And thanks for your contributions to more reliable mags.