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4/12/2009 11:33:16 AM EDT
OK, built an AR-15 (mostly, has takena  year to collect parts...). I finally got all the "working parts" together, and wanted to test fire it before I installed the handguards, as they will be over the gas block, and I won't easily be able to adjust the gas block once the handguards are on.

Double Star lower.
DPMS lower parts kit.
M&A M16 bolt carrier.
Bravo Company 16", mid-length upper.
BCM charging handle.
DPMS Buffer tube and buffer.
Wolff buffer spring.
Daniel Defense low profile gas block.

I removed the FSB from the BCG upper, and installed the DD low profile gas block.

Today at the range, I loaded 1 round, slapped the mag in, charged it, and fired. The round went off, but the case did not eject.
OK, gas block not over the hole, I figure. Loosen the screws, twist just a bit, tighten.
Load another round. Fire. Sure enough, the casing ejects, but the bolt does not lock back on the empty mag. (Which it will do if you charge it on an empty mag.)
Pull the trigger. Sure enough, the hammer was cocked after the last shot.
Hmm, just funny luck?
Load 2 rounds. Bang. Click.
I tested it a bunch, and it seems that it ejects the spent case and cocks the hammer every time, but fails to go back far enough to either lock open or catch the next round.

So, my question is: Is the gas block still not aligned correctly, or could it be that the Wolff heavy spring is preventing the BCG from going back far enough to function correctly?
(BTW, tried another ammo type too. First was using WWB 5.56, then tried Wolf just to see if maybe the rounds were the issue. Both had the same results.)
4/12/2009 11:59:13 AM EDT
[#1]
http://www.ar15.com/forums/topic.html?b=3&f=12&t=437510
4/12/2009 12:10:57 PM EDT
[#2]
I bought one of these when they were a prototype.

http://www.rainierarms.com/?page=shop/detail&product_id=1089

They are designed for aligning the gas port for dimpling a gas block.

They also work for marking the bottom of the barrel so you know where to mount most gas blocks.  
I set up a DD low profile gas block using one of these.
4/12/2009 1:47:37 PM EDT
[#3]
Check to make sure your bolt catch is moving freely,if it isnt you might have to work it down a bit so it will function as it should.
4/13/2009 7:15:35 PM EDT
[#4]
On a middie I'd think about not using the Wolf HP spring.
4/23/2009 2:27:04 PM EDT
[#5]
Quoted:
On a middie I'd think about not using the Wolf HP spring.


Bingo! I did nothing other than swap the spring with a DPMS one, and now it works just fine.
Thanks for the help!

Now to test out my new Magpul MBUS...
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