AR-15 Upper Building

TomZ

TomZ

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Eastern Ontario
All:

Well, I am jumping into the wonder world of AR-15 building with the recent purchase of a A3 Upper.

I am planning on buying and installing a 20" HBAR barrel and use the upper on my Armalite lower.

I came across this site:

http://www.ar15.com/forums/topic.html?b=3&f=4&t=226782

Which makes the re-barreling seem pretty simple (yes I bought the wrench and action block ;-).

I do have a few questions:

1. Do the "barrel extensions" normally some with the barrel or with the receiver?

2. Are the "rifle length" gas-tubes all made for a 20" barreled rifle ?

3. Should I get headspaces gauges to be sure of my install?


Anyone in the Ottawa area that can help me if I get into trouble once I get all the parts I need ?

Tom
 
You will be able to handle the job just fine. Barrel extension is on the barrel already, that's the thing the bolt locks into.
Rifle length gas tube is for a rifle, carbine lenght tube is for a carbine. Also midlength but we won't worry about that.:)
No worries about headspace guages, the barrel extension is already headspaced for you. With a new barrel it's good to use a new bolt, but not necessary.
 
Usually the barrel extension comes with the barrel. Standard gas tubes are the proper length for the gas block to be in standard position. This means that handguards also fit. You should get headspace checked, but generally speaking a finished barrel with extension installed should headspace with a stock bolthead.
 
Thanks guys.. i will let you know how I make out. I expect to have my receiver in a few days and then the barrel in a week or so. This should be fun!

Tom
 
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My only advice, above and beyond the great advice already given, would be to make damn sure you have the right tools for the job. I learned the hard way on my first upper. Tool marks look really nasty on aluminum uppers and handguards.
 
Wow! What fun!

I have successfully mounted a DPMS 20" 1/7 HBAR onto a new A3 upper and I range tested it today installed on my Armalite lower.

With Winchester whitebox 62gr ammo I was getting about 2.5" groups at 100 yards. Yipee! It looks like all worked fine!

I bought the correct tools including a armourer wrench, action block and gas-tube alignment pin from Browmells. With the correct tools this was an easy job and I am certainly not "mechanically" inclined.

Next I am going to work up some handloads and then start sourcing and building a new lower.

Thanks again for the advice ad encouragement!

Tom
 
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