have you been here?
https://forums.brianenos.com/
I learned a lot over there.
So hear is my story, I will probably repeat myself from the couple of threads I link to above.
I first built my daughter a 9mm AR for her 16th birthday, colt style and it is flawless. The good is she can remove the adapter block and the upper and she has a milspec lower she can then run anything from 5.7x28, 223/556 up to 50 beowulf. That is the nice thing about an AR15 lower the modularity is amazing. The only bad thing for me is that with the mag inserted it is ugly as fuck. Functional but ugly.
It is a blast to shoot, so I wanted one.
This was right about the time 9mm AR's started to become a "thing". When I built hers all the info was colt conversion info. 6 months later Glock lowers started to appear. Even though I never have owned a Glock, I liked that idea for two reasons. Mags are easier to find, and in case I ever did get a Glock it could share mags with it. I failed to see a couple of down falls with that idea.
The biggest is that you loose a lot of your AR15 modularity. The only thing it can be converted to is a 40 cal (357 sig I assume also) Glock PCC.
I SBR-ed it. It had some growing pains, worst of which were feeding hollow points (feeds fine now) and breaking BHO, current one is a Seekins that has been in there for a long time (did you know it is a MIM part?)
It is fun, but still ugly.
BUT
Then came the Endomag last year. Think about it, no conversion block. Keeps all the AR15 modularity. AND it looks like an AR15, training is the same, mag pouches the same, muscle memory is the same. The only negative anyone can find and
@hermosabeach mentioned it first in one of the other threads above, is the possibility of getting the 9mm mag confused with a regular mag or vice-versa. My fix for that is color coded mags, same as I have done for my 300BO.
I went with a Aero Precision lower. a FoxTrot Mike side charging upper (because of reviews and in this case the side charger is going to be very handy)
https://fm-products.com/
The Endomag has one thing that is different. The ejector is built into the Mag adapter, so if you eject the mag and then try to unload, the cartridge in the chamber will stay under the extractor and just go right back into the chamber.
The correct unload/clear procedure would be. Pull bolt back, round in chamber ejects, while holding CH back eject magazine. This takes a little training and may turn someone off. If the Mag runs dry the bolt does hold open. This is where the side charger comes in very handy. Pull charing handle back, use other hand to manually activate the BHO, eject magazine, visually verify clear. If range required insert chamber flag. This is all easier I feel with the side charger. Also because it is my only side charger, muscle memory is building to make this become habit.
I tried a couple buffers and springs in my Glock SBR and finally settled on this.
https://taccom3g.com/product/taccom-pcc-adjustable-buffer-system/
So I used it in my Endomag build also. Works very well.
Originally I took the upper off my glock and put it on my NFA- SBR registered mil-spec lower, I did this to test the Endomag before I built a complete gun. I put lots rounds through it (number is in threads posted above, over 1000 in 3 outings I believe). It worked great except for when I put slight up pressure on the mag, the bolt would hit the ejector. This is where the last Mean arms video comes in. Not all bolts are cut to the same specs.
I just put the gun together at Christmas and have about 300 rds (100 rds of various hollow points) through it. It is flawless, with no malfunctions at all. No mag "break in" needed at all.
The only issue with a complete gun from CMMG is that the lower is glock mag only.
You can buy just and upper and use the Endomag or this
https://getstern.com/products/magazine-adapters/
They are supposed to run really well. Either of those two allow you to use a standard lower which leaves your options open.
I have the stencils made for 9mm, I just need to prep the mags and paint them, along with doing the mag base plates blue also.
I do have a suppressor I run on the Glock SBR, I will have to see about shorter hand guard from Foxtrot mike to run it on the new gun. Over all I love it, the mechanics of operation are just natural if you shoot a AR15 at all.