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9/19/2017 7:27:10 PM
Posted: 12/22/2005 6:52:08 PM EDT
Ok the lower is the easy part, and I'll probably go with the ace tube. The upper is where I'm going to have some questions.

1) do you have to have a special gas tube/system for pistols?
2) I was looking at the cmmg upper just posted a few down and was wondering what length and make of railed handguard that was?
3) referance to the above I want to put a noveske brake on it but I don't want any of the barrel behind the brake to be seen and was wondering if the handguard on the cmmg upper would accomplish this.
4) what type of gas block is used if I don't buy a barrel with a block.
Link Posted: 12/23/2005 10:00:31 PM EDT
Check out CMMG's web page. They'll have info on there.

It all depends on what barrel length you go with. The two gas systems used are "pistol" and "carbine". For barrels under 10", the "pistol" tube/gas hole location is used. If it's longer....usually it's in the carbine postion and the barrel is just less then 16".

The key to getting a shorty (6"-8") running is the gas hole size. By now, I think most people know what size it should be. You could use a special gas block that can be adjusted.

I created a thread that was just tacked talking about uppers for pistols...take a gander at it....


Link Posted: 12/24/2005 9:45:10 AM EDT
I'm wanting to build a 7.5 upper. I was wanting to piece together the parts as I have funds. When you say shorter than 10" needs a pistol gastube and hole does that mean there are special gas tubes and the upper has a diffrent hole in it?
Link Posted: 12/24/2005 10:57:46 AM EDT
shorter than 10" uses the pistol gastube and the short 7.5" bbl. has its gas port in a different spot which is located under the gasblock/front sight, something you shouldnt have to fiddle with.


Link Posted: 12/24/2005 11:17:01 AM EDT

Originally Posted By STEEL1212:
I'm wanting to build a 7.5 upper. I was wanting to piece together the parts as I have funds. When you say shorter than 10" needs a pistol gastube and hole does that mean there are special gas tubes and the upper has a diffrent hole in it?




There are 3 (common) gas tube/hole locations and lengths of gas tubes.
-pistol
-carbine
-rifle

The other 2 are "so-so".
-midlength
-extended

Look here for a slight explaination and pictures: Link to gas tube/hole locations

To sum it up, the 7.5 works, but the velocity of the round will be much less then say a 8 or 9" upper.
Look at this barrel and data: Data


Link Posted: 12/24/2005 11:42:26 AM EDT
RB precision in the EE is a good source
Link Posted: 12/24/2005 6:15:13 PM EDT
I'm not really concerned with velocitys and fragmentations from the 7.5 barrel. I'll sbr something later with a 10.5-11 barrel if I want to do that, this will just basically be a range toy.

So I can use any upper though right? The gas hole that is in question is on the barrel right?
Link Posted: 12/24/2005 6:22:12 PM EDT
Correct... the only barrel-length specific parts are the barrel, the gas tube and the handguard/FF tube. The upper receiver is universal.
Link Posted: 12/24/2005 6:49:15 PM EDT
10-4

I'm gathering pieces and haven't decided on the 1/7 1/9 barrel yet.
Link Posted: 12/24/2005 7:56:19 PM EDT
If you buy a barreled upper with a 7.5 " barrel from a reputable dealer you
dont have to worry about the gas port - they all know what works.

Unless you plan on shooting ONLY heavy bullets , the twist doesnt matter either.
(for a range toy )

A "shaved " gas block will fit under any float tube or rail handguard.

I recommend using a full length buffer and tube. ( like the Ace or Model 1 sales tubes)

Also , unless you already have detachable sights - or want something special ,
I suggest a plain flat top with a cheap but sturdy red dot , will work great
at 0 to 100 yds , or even further.
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