They didn't strike out the grandfathering, they struck out the date from the old law and amended it to 2013 (S38 Sub 23 C).
As written, that says this: a large capacity ammunition feeding device means a magazine, belt, drum, feed strip, or similar device that:
A: Can hold or be easily made to hold more than ten rounds OR
B: Is actually holding more than 7 rounds of ammunition OR
C: Is obtained after -effective date-.
Note that they don't say AND. They said OR. So, by the basic, raw, unedited and uninterpreted law itself, all magazines/drums/feed strips/etc., purchased after the effective date are all illegal - even if they only hold seven or less.
There is no provision in there *allowing* previously owned magazines. That's not grandfathering.
As for your 1911 quip, can you show examples of similar language banning extended magazines and thus guns that accept them? The language you quote there says magazines that attach outside of the grip, whatever the fuck that means. Even extended magazines go inside the grip and attach inside the grip, even if they extend out of the grip.
What they apparently intended to do was ban something like the TEC-DC9, which had the magazine in a housing forward of the grip:
What they actually did was ban any pistol with 'the capability of accepting a magazine outside of the grip.'
Which means:
1. Any pistol with a Picatinny rail is or could be banned because you can buy a magazine holder that clips on to the Picatinny rail now - that 'accepts a magazine outside of the grip.' Note that the law doesn't say the weapon has to accept and feed off the mag, only that the
capability to accept a magazine must exist. Here is one such device for a rifle (best pic of this type of device I could find):
There are lots of 1911s that have Pic rails now.
2. There are also pistols that can take a magazine clipped upside down ahead of the trigger to aid in stabilizing. The one in this picture is an illegal machine pistol, but the semi-automatic versions sold in large numbers in the US can do the same thing:
Even if you don't have the actual magazine installed there, by the letter of the law, that's 'capability to accept outside the grip' and you're done.
There are baseplates for 1911 magazines that allow them to do this as well.
As for prior language being interpreted so? Easy. NYC (not state, NY City) has had similar language in place for its (few, privileged) permit holders for a long time. It is interpreted as "no magazines that protrude from the grip". Discussion from people that found this out:
http://www.ar15.com/archive/topic.html?b=8&f=9&t=257590
Further the 1911 would/could be banned by the "semi-automatic version of a fully automatic weapon". In the 1940s, Colt built some fully-automatic 1911s in .45 ACP and .38 Super and received US patent number 2462505 for it. Here is one of them with all of its accessories:
This is one of the .38 Supers that was built:
Before you ask, yes, they could be fired without the appliances attached in full auto.
The Browning High Power is out for the same reason, as the Nazis had the Belgians build some FA ones. So is every Beretta 92 (it's an evolved version of the M1951A and is actually the semi auto version of the Beretta 93R machine pistols). The CZ75 and it's hundreds of derivatives as well due to the CZ75 AUTOMATIC machine pistol (caps theirs.)