Did you clean the gun thoroughly before trying to load it? I know that sounds funny, but some of the mfgs. tell you to clean the gun before you use it the first time. Also, check the bottom of the brass for it's stamping and caliber information. It's entirely possible that ammo could wind up in the wrong box even from the mfg. When I first bought my Taurus .38 Super, I bought 2 boxes of Remington ammo. Not one shell would chamber properly, and if it manged to get into the chamber, I could not extract it without extreme measures. I sent it back to Remington and they told me it was up to specs....but they did credit me for the ammo, much to their "credit". Since then I have shot any ammo I could find, except Remington and never had the problem again. I also reload and have never had the problem. The LGS basically said that "some guns don't like some ammo". I guess they were right, and perhaps you have come across the same issue.
Never waste time deciding between two guns....buy both of them.