AR-15 Stripped Upper Question- Is it Caliber Specific

Haris1

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Hello All:
I have never assembled an upper.
If you want to assemble it in 9mm or 45 is the stripped upper different
than a 556 upper?. I dont think so but i want to make sure
Thanks for looking
 

A&S Conversions

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What system are you using? Original Colt 9mm uppers used standard ejection ports, but there is no gas tube hole. The CMMG RDB system has ejection ports that are opened up to the size of the port door.

Scott
 

SecondAmend

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Both of my AR 9mm upper assemblies feature Gibbz Arms G9 upper receivers. As the model implies, the G9 uppers are designed primarily for 9mm usage (and also are sometimes used for .22 usage). Right To Bear (RTB) also sells an AR upper that is designed primarily for 9mm and .22 usage. I have one of the RTB upper receivers for a .22 AR application. There may be others as well.

Disclaimer: I have no affiliation with or financial interest in any vendor or manufacturer; and I am not a competitive shooter or a blogger who receives any form of compensation for endorsements or favorable public or private comments. Use of vendor and/or product brand names, if any, is for informational purposes only.

Best of luck.
MHO, YMMV, etc. Be well.
 

cajun 22

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Any upper can be used for a pistol caliber. The only difference is the bolt and barrel used.
 

sniperdoc

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Any upper can be used for a pistol caliber. The only difference is the bolt and barrel used.

This is my understanding, but there are a ton of newer ones out there, so I didn't want to say(write?) outdated information
 

ericthered

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The only differences I have found in uppers through my looking in regards to ezjection ports, is that there is standard ejection port that works with pretty much everything, there is a smaller port that is specifically for pistol calibers. Then there is enlarged ports for the 500, 458, and 450.
I just put together a 9mm pistol that used the standard port size.
Im not a authority on the subject in any way, so maybe there are some other port variations.

Obviously there will be different looks. Side charging, dust cover, foreward assist etc
 

amphibian

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As others mentioned, it depends on what system you are using.
Straight blowback setups that rely on a fixed ejector in the lower can get away with a smaller ejection port.

The CMMG Radially Delayed Blowback (RDB) have a similar bolt / carrier relationship to a standard gas operated BCG like seen below but notice the angles on the bolt lugs and there is no 'gas key'. It is solid in this case.
IMG_20171112_150527066.jpg


CMMG uses what appears to be a standard upper but the ejection port is clearanced slightly in front of the port door detent you can see the difference.
IMG_20171112_145709056.jpg


It is the same as the Aero XL uppers which were previously marketed as their 458 Socom upper. That is what I use for my CMMG RDB's in 9mm / 40SW and .45ACP.

There are some people that report success using standard unmodified uppers for the CMMG RDB 9mm...so YMMV.

Info on the CMMG RDB on my website here: https://c3junkie.com/?page_id=164
 

Haris1

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I think i may have bit off more than i can chew. I bought a suppressed upper that has a olympic barrel.I thought i could use the endo mags which is the size of a AR15 magazine but it contains 9mm in the back of the mag and the front of the mag is the feedramp
Only problem is that the Olympic upper woud not permit seating of the magazine. SO I removed the ejector from the upper receiver and now it wont eject at all
Now i hope to remove the barrel and change it for a CMMG Upper and cmmg barrel and CMMG bolt. I removed suppressor/barrel combo from the upper. I am clueless how to get the barrel out of the suppressor

The reason I started this thread is because i have a complete cmmg upper that I am hoping to use and attach the suppessor to the barrel
Any Ideas!!



 

amphibian

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Oh boy....

1. There are two different Endomag versions. One that is made for the CMMG RDB that relies on the ejector in the bolt. The other one has the ejector built into the Endomag on the mag itself. I do not like the latter since you must leave the mag in the gun to clear a live round.
All that said, they both are designed for different feed heights within the Endomag design. The CMMG RDB uses a barrel extension like you would see on a standard gas operated 556 barrel and requires basically the same feed height as a 556 mag. With a straight blowback 'Colt' 9mm design, the feed height is higher. On the OLY system which is also straight blowback, I do recall it uses a fixed bolt in a carrier but I can't recall what the feed height needs to be.

Regardless, I haven't heard of anyone using an Endomag with an OLY system but sounds like you don't even want to use the OLY system and just salvage the suppressor for use with your CMMG right?

2. I'm not clear as to what you have going on with that second to the last picture where you have male threads coming out of the suppressor. Does your barrel have female threads and the can screws in that way? This isn't an integrally suppressed setup is it? Maybe if you posted a picture of the entire setup it would help.

3. I think this is wasted effort to use that can. Many great cans out there and I wouldn't bother or just plan to get the can modified to work with the CMMG RDB. I would send the suppressor to Curtis Tactical and have him make the can user serviceable if it isn't already and re-do the mounting system depending on how it is now as I can't tell from your pictures how it is mounted.

I have an integrally suppressed 9mm setup using a ported barrel for the Colt system and I've been wanting to get it re-cored and then have a custom SS CMMG barrel made to work with it but am on the fence to doing it in hopes that MEAN Arms releases their delayed blowback system which I hope will be superior to the CMMG system. Then get a barrel turned down for that system because both the CMMG RDB and MEAN have extensions where the bolt engage to create the delay unlike regular straight blowback systems.

You can see pics on my site of what Curtis Tactical has done for me and I've always been very impressed.
https://c3junkie.com/?page_id=244

https://c3junkie.com/?page_id=553
 

Haris1

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And Amphibian said:
Regardless, I haven't heard of anyone using an Endomag with an OLY system but sounds like you don't even want to use the OLY system and just salvage the suppressor for use with your CMMG right?


That is correct Amphibian, I will discard my OLY upper and hopefully I can use the suppressed unit with my CMMG

That is my unit. I probably should have contacted Curtis Tactical first. I may have spent $1,000 and its useless. Or maybe Joe can mount my suppressor to my Cmmg RDB upper

My unit has a muzzle cap that keeps the handguards secure
I have been unable to remove the barrel from the suppressor. I will just sent everything to Joe




Amphibian- tell me what pics you still need to understand this if any
My Form 3 says 11.5 inches but i think the barrel length is something like 4 or 5 inches since i only see rifling part of the way
 
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amphibian

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OK. That helps a lot....yeah IMHO, you wasted 1k on a tube if you aren't even going to be using the OLY system.
Should have started with Joe at Curtis Tactical to begin with.

Pictured below is my custom CMMG 9mm RDB barrel:
length-1024x349.png


It was a straight blowback 9mm barrel that I had turned down with an extension put on for the CMMG RDB system.

It is stainless. I went that route in case I wanted to go integrally suppressed so that when carbon build up gets on it, I can just toss the thing in the ultrasonic cleaner with harsh chemicals and not worry about messing up a blued or nitrided finish.

I did the same thing when I had a .45ACP RDB barrel made.
45-bbl-2-1024x394.jpg


https://c3junkie.com/?page_id=164
 

Haris1

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Amphibian:
You are correct
The main reason i bought it was that the OLY 9mm mag fits into 556 sized magwells and I thought the Endomag would work
It wouldnt even click in
Well, I will contact Joe now

[B]Joe from Curtis Tactical called me up and I am sending him my unit
He has made me one suppressor for a MPI 69 and I also own a CTK9s
I am very pleased with his work
[/B]
 
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