Just thought I'd pass this along.
I have a Ruger PC-9 9mm carbine. It uses Ruger Pistol magazines, but I happened to notice that Walther P-99 magazines were very similar. Sure enough, with a minor modification, Walther P-99 (and presumably S&W SW99 mags) will work in a PC-9, although the bolt hold open device won't function.
To modify the magazines, you need to mill a small horizontal slot in the front of the magazine body about 0.200 wide so that the top edge of the slot is 1.700 from the front lip of the magazine. I used a 1/8 inch end mill. The magazine works flawlessly in both the carbine and the Walther.
I have a Ruger PC-9 9mm carbine. It uses Ruger Pistol magazines, but I happened to notice that Walther P-99 magazines were very similar. Sure enough, with a minor modification, Walther P-99 (and presumably S&W SW99 mags) will work in a PC-9, although the bolt hold open device won't function.
To modify the magazines, you need to mill a small horizontal slot in the front of the magazine body about 0.200 wide so that the top edge of the slot is 1.700 from the front lip of the magazine. I used a 1/8 inch end mill. The magazine works flawlessly in both the carbine and the Walther.