Date code of last USP changes...

[99999]

I am looking at buying some NIB older USP's, but wanted to make sure that if I did, they were still just as good as the new ones. Big Bore had some info out here, but I couldn't find it very well by searching. Does anyone know when the last changes were made to the USP design and what Date Codes they would be represented by? I don't mean like the HK usp vs USP on the grip, just major changes like larger springs or what not....

[S_Phoenix]

The early ones had land and grove rifling vs polygonal, so looking at KE, KF's maybe. I don't know when they added the trigger lock.

[Tyrael]

Not sure on the date about the trigger lock either, but my KI dated USPc doesn't have it.

[SIGtrarian]

There was a change in the firing pin/firing pin block between AE and AF. You can see it from the under side of the slide if you look closely.