Found a great price at GunMag Warehouse on ETS 30 round mags for M&P pistols.

Since my new S&W FPC carbine takes M&P pistol mags I ordered some.

Well…
The mags won’t lock in with the bolt closed, whether loaded or empty.
With the bolt open, they lock in but the bolt will not close.

I emailed ETS about this.
Here is their response:

“Our current mags over insert in the FPC making them incompatible. However, we are working on a new Omega S&W M&P P320 that will be compatible with the FPC. We are hoping to have that available in the next few months. 
You can either hang on to those and swap them out once the new mags are available or you can send them in for a refund now. It is up to you! 

Thank you,
Sara John
ETS Group”

This may be a known issue, but when I did my Internet research I was only looking at the reliability of the mags.
Somehow I missed this issue.

Waiting on word from GunMag Warehouse about a refund since I have opened some of the mags.

I’ve had mixed results with ETS mags.
Worked great in a MP5, didn’t work in a Glock, even after ETS sent replacement mags.

Oddly enough these mags seem to fit and function in my M&P pistols.

Oh well.
Live and learn.

Mine doesn’t even run well in my pistols, nor a friend’s. If ETS allow you to send it to them for a direct replacement with the new model, let me know.

Wow, you just saved me a lot of money and trouble.  I was eyeballing those 30 rd mags pretty hard and the price is certainly right.

The 23 rd S&W mags are excellent and look like they'd last a lifetime, so maybe I should stick with those.

Sticking with factory mags is a good plan.

I just shipped them back to GunMag Warehouse.
Hopefully I won’t get stuck with a restocking fee on the open ones.