The Definitive Colt MK18 / CQBR SOPMOD Block II Build

[xWRANGLERx]

I'll agree with you about the Daniel defense upper I didn't feel it was extremely over gassed (in there defense it's so people can shoot all the crap ammo they want and so they don't get multiple calls about why the uppers not working) that's why I ended up parting it out and keeping the rail and now I'm buying a 14.5 colt barrel and cutting it down to 10.3" along with opening up the Gas-port to the diameter that you mentioned ".070"

[n4p226r]

Your stock DD MK18 upper should prove reliable but it is my experience that they are severely over gassed when using hotter ammo (closer to Mil-spec). One way to mitigate this is to use an adjustable gas block, but it also adds additional potential points of failure.

I think the best options are:

- Have a quality 16" barrel cut down to 10.3" and have the gas port enlarged to .070"
- Source a Mil contract 10.3" barrel (which has the .070" gas port).


If one of the above options is chosen, avoid using under-powered ammo in the gun.

NEWBIE question
when someone says this, what is considered "under-powered" ammo? is something like 55 grain american eagle AE223 or PMC 223 lower powered or are you talking the really cheap stuff?

[PFran42]

More like Tulammo

[n4p226r]

ah. yea. i've never used that.

[xWRANGLERx]

Right on thanks I'm also a lefty but I shot long gun right handed you should look at a upper receiver that ejects the brass to the left (not clone correct but would be nice)

[BooneGA]

Right on thanks I'm also a lefty but I shot long gun right handed you should look at a upper receiver that ejects the brass to the left (not clone correct but would be nice)

Why? There are, believe it or not, hundreds of left handed men who are issued MK18s and don't have an issue using the weapon in a combat environment.

[sua175]

My best friend is a lefty and has never had a problem shooting a army gun a day in his life, and that's including not having a ambi safety


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[PFran42]

Maybe my eyes are just super sensitive. I've had to go to an Optometrist after shooting the MK18/CQBR suppressed during extended sessions over a weekend. I would guess I only went through 600-700 rounds (and that is half the amount that you would go through in one of those high-round-count two day courses). I was shooting NTCH and I clogged some pores in my upper and lower right eyelids. It looked disgusting. The doc had to lance them. I've never been allergic to anything. I've probably been to a doctor 3-4 times in 43 years. I couldn't believe what had happened. Maybe it was the ammo. I was shooting ZQI SS109.

[sua175]

What charging handle were you running?


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[PFran42]

What charging handle were you running?


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PRI M84. It directs gases directly into a left-handed shooter's right eyeball. Thing is, it didn't really hurt or anything while I was shooting. I just felt like my right eye was a little irritated after the first day. Same thing the next day. But by Thursday of the next week, it looked like I had eyeball AIDS.


EDIT:

And yes, before anyone asks, I was wearing eyepro.