Most mags you buy today, in fact almost all, like 99% are early release.
Only old GI mags and current Checkmate GI mags are not, at least as far
as I have been able to find out.
If you have mags, look and see if the lip fold over ends just past about half way from
front to back of the mag. If so, it is early release. You have to hunt hard to
find original style mags these days. I suspect that you already have them.
The ones that Brad has pictured have the lips tapering, but going almost all
the way to the front with the lip. This is the original John Moses Browning lip design.
Here is a good photo.
Both the "wadcutter" (I call them parallel lips, early release) and hybrid (tapered lips like JMB intended,
but early release) are "early release types which tend to work better for short nosed bullets than
the original GI (JMB) design. For normal length ammo, all guns tend to do very well with the
GI lips. And some guns demand them for utter reliablility.
Gunsmiths in the Bullseye days would hammer out the lips of GI mags to make them release earlier,
let the rear of the round pop up to avoid the roof jam with short nosed cartridges After a while these mags
were made new that way. Then somebody made the lips parallel. Now that is nearly standard....IMO, out
of ignorance. Don't know if Laka originated the parallel lips or not, but it is an early parallel mag, used
only for Bullseye competition in the 70s and 80s, probably earlier.
Much ignorance on the 1911, as ubiquitous as it is, and way too many folks who really don't know what the
heck they are doing modifying stuff, like mags. And they the original design intent eventually gets dropped
through a crack. Which is why I periodically put the facts and history out there, hoping to spread the word
a bit more before it is lost forever.
Bill