They can be loaded without damage when everything is new in the box, but it takes some effort. My M&P 45 is about a month and a half old. The mags have sat fully loaded that entire time and the tenth round is still tough to get in the mag and it still requires a little effort to seat the mag on a closed slide, but less so than before. My Glock 21 was the same way, but it is a couple years old now and things are quite a bit easier.
One of my magazines has the same problem and it never did work. As you said you really have to struggle to get the 10th rd in and then it took alot of force to get the magazine in the gun. When I tried this magazine with the side open it would not feed the first round properly. Round would nose dive. If I loaded 8rds magazine was good til the last round and gun would jam. Gun is 100% with other magazines. The mags just don"t look to rugged compared to say an XD mag. As we know the magazine is a very important part. I know you have heard problems with bad mags in the beretta's m9 in Iraq. So far I like the M&P. I have several XDs and have never had a mag problem or a jam with any of them "Kock on wood". My trigger pull seems harder than 6.5 lbs and is quite gritty. I guess if I send it off for trigger work it would void the warranty. I feel the factory should take just a little more time and polish the inside up a bit. I don"t think S&W offers and trigger work. I have also owned several Glocks and they were very good but I did not like the fill of them.
I was told by a person answering the phone at S&W that the warranty would be voided if the particular part that was modified went bad, but if, for an example, you had a trigger job done and the slide or frame cracked, it WOULD be repaired under the warranty. I also ask about some throat work on the barrel if it was needed to make 200gr cast SWC feed. The guy gave me his name and said that it would not void the warranty. If I had a problem, use his name. Take it for what it's worth.
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