Easy way to do it would be like this https://www.hkparts.net/shop/pc/Kyde...ING-p18916.htm just get something like that ( many people use clear Kydex so does not look so bad ) make sure it does not have flash hidder or folding stock and your good to go ...And if you happened to get some 20 round mags the last time they liffted the ban in CA they can be used with that set up ..Not a lawyer though
The only thing to note is this gun a papered gun in CA ie did you at some point paper it as a AW etc either in the 2000s or ?
oh I'm keeping my 911 even after that crazy offer. For one I like it and the history behind them. H&K or who ever came up with the idea to just stamp a 1 behind the 91 and it past customs. Also I was told my the original owner that the first hundred that past custom just had the 1 stamped on it. He said the about 100 when thru before custom catch on and have them add the stock and the fake suppressor. So I feel lucky own it.