You are probably going to be fine with any off the shelf ammo. There are probably scads of guys on this forum who shoot factory loads through vintage 99s on a regular basis with no problems or thought given to what they are doing. Now having said that, you should have the 99 in question checked by a competent gunsmith before you shoot it if you have any cause for concern - especially if there are any issues with the firearm that have not been brought to light in during the course of this thread.
