Just purchased a used P3AT. Its looks to have been shot very little. Cleaned alot of pocket lint out of it...then took it to the range. I ran probably 75 rds without a problem and accuracy is good for a little pistol. My question. Is it in the design that these pistols DONT lock open when the mag is empty? I tried 2 mags and neither one would lock back. Seems a little strange that it would be designed not to lock open.....but this is my first experience with this model so I thought I would ask. Thx in advance for the info.