Hi William and welcome. I would disassemble, clean and lightly lube the magazine walls. Please leave the magazines fully loaded for a few days or download them by two rounds until the high-tension spring breaks in. Smith and Wesson Customer Service may be able to advise you better at 800-962-2658. Cheers, stay safe and enjoy!

Common Issues with Smith & Wesson M&P 22
Feeding Problem
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The Smith & Wesson M&P 22 may experience issues when the magazine is fully loaded. Users have reported that the firearm sometimes will not chamber a round under these conditions. This can happen due to several factors:
Drag from Rounds: When the magazine is fully loaded, the rounds can create enough drag to prevent the slide from moving back far enough to pick up the next round.
Slide Mechanics: If the slide is not cycling properly, it may not extract and chamber the next round effectively.
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Solutions to Consider
To address these issues, consider the following solutions:
Download the Magazine: Loading fewer rounds (e.g., 5 instead of 10) can improve reliability and allow the firearm to function correctly.
Lubrication: Ensure that the firearm is well-lubricated. Proper lubrication can help the slide operate more smoothly.
Ammunition Quality: The type of ammunition used can also affect performance. Switching to higher-quality or hotter ammunition, such as CCI Mini-Mags, may improve reliability.
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Additional Tips
Break-In Period: Sometimes, new firearms require a break-in period. Regular use may help resolve feeding issues as the components wear in.
Consult Manufacturer: If problems persist, contacting Smith & Wesson for support or service may be necessary. They can provide specific guidance or repairs if needed.

Good evening to you!! I suggest you contact the manufacturer. A new magazine designed for 30 rounds shouldn't have feeding issues. Contact S&W at smith-wesson.com/customer-service/contact-us.
Hope this helps. Have a good rest of your day.
🇺🇸🇺🇸 'Merica' 🇺🇸🇺🇸

Key Reasons for Failure to Chamber
Excessive Spring Tension (30th Round): When filled to 30, the magazine spring is completely compressed, leaving no room for the cartridge to move downward when you insert the magazine on a closed bolt.
Improper Stacking (Rims): The .22 WMR cartridge has a rim. If the rounds are not perfectly staggered, the top round can get stuck behind the rim of the round below it.
New Magazine Break-in: The springs are stiff and need to be worked in, similar to reports from other M&P 22 Magnum owners.
Recommended Solutions
Load 27-28 Rounds: As you noted, the magazines work better with slightly less than maximum capacity. Loading 28 rounds instead of 30 allows for enough spring compression for the magazine to seat properly and the bolt to function reliably.
Break-in the Magazines: Leave your magazines fully loaded for several days, then unload them and load them again. This helps relax the springs, making them easier to load over time.
Ensure Proper Staggering: When loading, make sure the rounds are perfectly alternating side-to-side. If a round looks odd, disassemble the magazine (if possible) or unload it and try again.
Insert on Open Bolt: When using a full 30-round magazine, lock the bolt back first. This relieves the pressure required to insert the magazine, as the follower doesn't have to compress against the bolt itself.

I would contact S&W customer service @ smith-wesson.com/customer-service/contact-us