I wanted to make a thread to help everyone that are new to or looking for help with their FM-9. I searched the subreddit to see if anyone had made a thread like this dedicated to Foxtrot Mike products and didn't find anything related. I have been lurking and trying to help where I can.

I bought my first AR-9 during the COVID-19 pandemic, so I am still very new to this. I bought my FM-9 5" upper from Schuyler Arms and my FM-9 complete lower from Primary Arms. I did not build it from scratch.

I purchased the mags that were recommended by Foxtrot Mike that were listed on the packaging and on there FAQ on the website. https://fm-products.com/faq/ . OEM 33rd Glock, Magpul 27rd Glock, and ETS 31rd Glock mags were what I purchased. My experience with them are as follows. OEM 33rd Glock mags worked flawlessly with Winchester 115gr Steel case and Winchester 115gr white and red box brass case. Magpul 27rd Glock mags had failure to feed issues with the Winchester 115gr steel case and worked flawlessly with Winchester 115gr red and white box brass case. The ETS 31rd Glock mags were only fired with 115gr Winchester red and white box brass case and worked flawlessly. I did not test the ETS mags with the steel case ammo I had. I will try next time I go back to the range.

Before I went to the range I contacted Foxtrot Mike and asked about their recommended break-in procedure. This was their response to me:

As far as break in, we mainly shoot about 500 rounds of steel cased (Tula or Wolf) ammo to break in our guns.  Couple things that will help a lot!

1) blowbacks need to be oiled real well when they are new.  We ship them with a corrosion inhibitor, and sometimes people think it is oil.  We like customers to oil the bolt, inside the upper, the buffer and buffer tube (no dry film, oil).   After it is broken in some, it will require less oil, but when they are new, this will help a lot.  

2) hi cap mags: when a hi cap mag is loaded fully, it exerts a ton of pressure on the bolt.  We recommend loading the mags 60% full, once it is broken in, you can fully load the mags. 

3) Please use a  6oz buffer and .308 carbine recoil spring.  No blow back will feed reliably with a standard carbine buffer and spring.

4) Dont use ammo with less than 1100fps, a blow back has to move a ton of mass, so anemic ammo will cause problems with a blow back, that dont occur when it is used in a handgun.  

Thanks for the email!  Paul

I hope this post helps those of you with questions. Please feel free to comment on this post with questions about my experience with the Foxtrot Mike product.

I really hope I didn't break any rules with this post. I don't post much on reddit, but felt like this may help someone out there. I posted from my phone and am not the best writer out there, so please give me a little break for the long winded post.