Scholars,
I am looking for some help as I prepare to dive into the 9mm upper scene this weekend. I just made a trade into a CMMG 9mm upper. 16" w M4 profile barrel. It came with the bolt and buffer, spikes magwell adapter and 5 c products 32 round mags. The upper shows some use but, I traded a $400 handgun for it. Upper was purchased from Brownells per the last owner.

My upper does not have the large shell deflector I see on most 9mm upper, should I be worried?

I have been told that I do not need to change my hammer with this set up.

I am just looking to get some info on trouble shooting possible visible things with my set up before I go blasting. I know that with it being blow back the gas system is non existent. Should I check anything about the bolt? How about testing the depth of my mag well adapter ahead of time?

Please, treat me like the noob I am with this thing and give me ALL THE INFO.

Pics to come.

Bev

That large 'shell deflector' is actually a gas deflector....not really needed...more for if you shoot suppressed.  Of course this is just my opinion.

That is good to know. I have a form 4 and form 1 pending right now. Can that gas deflector be added to my upper when time is right? Or would I need to purchase a different upper?

Thanks for the info.

I have had mixed results with the c prod. 9mm mags.  2/4 run flawless.  pretty sure the offending mags need the lips bent to match the working mags, but I got a deal on colt/metalform 20s and 32s, and those all run great.   Buy a lula loader, thank me later.
Pretty sure you can buy a gas deflector and add it on.   If you put a can on the gun you will want all the gas deflection you can get.   I was running a friends colt suppressed subgun, and after a couple mags I was unable to see clearly from all the gas in my eyes.
You may need to tweak the ejector finger to get proper ejection, I had to with my spikes block.
In this pic you can see I had to bend it inward about .10"

Look here for more info 9mm info

PERFECT!

This was the type of stuff I am looking for. Thanks for the info. I hope I can get out and burn up some federal bulk pack. I purchased a couple of boxes of Czeck +p+ to try through it.

Bev

You can buy one, it's only like 15 dollars from CMMG.

So I have the upper running. I just can't seem to get it to adjust far enough up to actually sight it in at 25. Rear sight is all the way up and front is all the way down. F marked front sight post. Can anyone tell me what front sight post they have?

At 25 yards I am still a foot low.

I'm thinking f marked sight is the wrong one for this gun.

Bev

Before
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I had a ton of problems with front sight height. It came with an F marked sight that was to high. The guy I bought it from put the front sight tower on and I could not get it to line up correctly. It was to tall and it looked like he used a ball peen hammer to put it on. While I was pricing front sights, I got a chance to nab a NIB YHM flip up gas block that bolts on. I figured this would be the perfect time to try a dissy look out on it.

After
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Range time this afternoon to see if it dials in correctly now.

Bev