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Posted: 3/7/2010 9:33:13 AM EDT
Just took a new build to the range. The rifle will extract the spent case, but will not load a new round into the chamber. I have tried Rem, Hornaday, Bitter Root ammo, and Wolf. I have tried 3 different Mags as well.
HELP PLEASE.
Rubar01
Link Posted: 3/7/2010 10:00:02 AM EDT
[Last Edit: 3/7/2010 10:01:48 AM EDT by locke12]
Does it jam? Much more info is needed for an Internet Diagnostics Session. Complete weapon configuration, mag capacity, etc.
Link Posted: 3/7/2010 10:06:15 AM EDT
Locke12
No it does not jam.
Bravo Co. - Upper
Bushmaster -  Fluted 16 inch upper
DPMS- Lower
Bushmaster - BCG

Thanks for the help
Rubar01
Link Posted: 3/7/2010 10:17:51 AM EDT
Hmmmm,  leak somewhere on the gas system most likely.  Don't think the buffer would be at fault with all the different ammo.



Link Posted: 3/7/2010 10:20:52 AM EDT
tried a different mag?
Link Posted: 3/7/2010 10:27:22 AM EDT
infidel666
I tried 3 different mags all with different ammo.
Thanks
Rubar01
Link Posted: 3/7/2010 10:29:21 AM EDT
traderpats
Do you think that the leak would be in the gas tube where it connects to the gas block or the gas block is not lined up with the port in the barrel.
Thanks
Rubar01
Link Posted: 3/7/2010 10:39:33 AM EDT
Originally Posted By rubar01:
Locke12
No it does not jam.
Bravo Co. - Upper
Bushmaster -  Fluted 16 inch upper

DPMS- Lower
Bushmaster - BCG

Thanks for the help
Rubar01


So, you have a Bravo upper and a Bushmaster upper and they both do this?
Link Posted: 3/7/2010 10:42:21 AM EDT
Short-cycling for whatever reason - inadequate gas pressure, parts dragging in the upper and/or buffer tube. It obviously loads manually, which strongly indicates the bolt carrier does not cycle back far enough during firng to pick up the next case on the return. First, check for dragging- with no magazine and no ammo, just pull the handle back and slowly ride it home. If it moves smoothly and easily, friction may not be the problem and you'll have to check the gas system. Also look for shiny metal shavings in the action or any other signs of unusual dragging.
Link Posted: 3/7/2010 10:47:03 AM EDT
CONKLE73
Sorry for the confushion. I have a Bravo Upper and a bushmaster barrel assembly 16 inch H-Bar fluted.
Rubar01

Link Posted: 3/7/2010 10:51:11 AM EDT
Originally Posted By rubar01:
CONKLE73
Sorry for the confushion. I have a Bravo Upper and a bushmaster barrel assembly 16 inch H-Bar fluted.
Rubar01



What kind of front sight base / gas block and how is it attached???? (pinned or set screws??)
Link Posted: 3/7/2010 11:04:01 AM EDT
CONKLE73
Railed gas block YHM clamp on.
Rubar01
Link Posted: 3/7/2010 11:09:49 AM EDT
[Last Edit: 3/7/2010 11:12:55 AM EDT by locke12]
What kind of stock? Fixed or tele? Which buffer? Also, do a manual function test on the bolt catch system, to confirm that your weapon is physically capable of getting a full stroke.
Link Posted: 3/7/2010 11:13:19 AM EDT
[Last Edit: 3/7/2010 11:15:29 AM EDT by CONKLE73]
Originally Posted By rubar01:
CONKLE73
Railed gas block YHM clamp on.
Rubar01


My first guess would be that the gas block is not lined up with the gas hole correctly…

Of course make sure the weapon is clear before doing anything else!!!!

Disconnect the upper from the lower and pull the BCG & CH…

Loosen the screws that clamp the gas block just enough so that you can move the gas block a bit… Plug the chamber end with a spent case and some tape or something and blow in the muzzle as move the gas block back a little… you should feel the air flow increase and decrease as you move it… get it to where you have the most air flow and carefully retighten the screws making sure not to allow it to move…

Then range test…

If this doesn’t work, I would suspect that you might need to open the gas hole a hair.
Link Posted: 3/7/2010 11:13:49 AM EDT
Fixed stock, no idea on buffer, came on the DPMS lower, I have already done a manual test on the bolt catch and it works.
Rubar01
Link Posted: 3/7/2010 11:16:13 AM EDT
Thanks I will try and let you know
If I have to open up the gas hole, how do I know how much to open it up?
Rubar01
Link Posted: 3/7/2010 11:20:02 AM EDT
[Last Edit: 3/7/2010 11:21:15 AM EDT by bfips]
Originally Posted By CONKLE73:
Originally Posted By rubar01:
CONKLE73
Railed gas block YHM clamp on.
Rubar01


My first guess would be that the gas block is not lined up with the gas hole correctly…

Of course make sure the weapon is clear before doing anything else!!!!

Disconnect the upper from the lower and pull the BCG & CH…

Loosen the screws that clamp the gas block just enough so that you can move the gas block a bit… Plug the chamber end with a spent case and some tape or something and blow in the muzzle as move the gas block back a little… you should feel the air flow increase and decrease as you move it… get it to where you have the most air flow and carefully retighten the screws making sure not to allow it to move…

Then range test…

If this doesn’t work, I would suspect that you might need to open the gas hole a hair.


try blowing before you loosen, so you get a starting point.
Link Posted: 3/7/2010 11:24:04 AM EDT
Thanks
Ready to try
Will let you know
Rubar01
Link Posted: 3/7/2010 11:26:55 AM EDT
Sounds like it may be undergassed.
Link Posted: 3/7/2010 11:51:40 AM EDT
[Last Edit: 3/7/2010 11:53:05 AM EDT by CONKLE73]
Originally Posted By rubar01:
Thanks I will try and let you know
If I have to open up the gas hole, how do I know how much to open it up?
Rubar01


If that doesn’t work… slide the gas block back and check the size with the back of a drill bit… 1/16” same as .0625” bit should just barely fit in the hole…

That size is usually optimum for a carbine gas system (7”) with a 16” barrel.

If the hole is smaller then that I would say that was your problem…

If you do need to drill it out to open it up use cutting oil… go slow… (You do not want to break that drill bit) get a wooden dowel or aluminum cleaning rod and slide it down the bore to keep the bit from hitting the other side of the bore when you break through…
Drill press is best, but I have done it plenty with a hand held drill…

Link Posted: 3/7/2010 12:05:54 PM EDT
THanks for the help
Rubar01
Link Posted: 3/7/2010 12:37:40 PM EDT
My guess, and it's only a guess, is that it is short stroking because of friction of the new parts. Needs only to be broken in.
Get yourself some good 5.56 ammo and put a couple hundred rounds through it with a liberal amount of lube.
The 5.56 ammo will help hone the new surfaces and loosen things up a little.
Link Posted: 3/7/2010 12:46:07 PM EDT
Originally Posted By locke12:
Sounds like it may be undergassed.


Not normally an issue with BM barrels.
Link Posted: 3/7/2010 12:57:33 PM EDT
[Last Edit: 3/7/2010 12:57:57 PM EDT by CONKLE73]
Originally Posted By heavyduty:
Originally Posted By locke12:
Sounds like it may be undergassed.


Not normally an issue with BM barrels.


Agree...

The possibility of it being the barrel / gas port is slim…
The possibility of the gas block being misaligned is great…
Especially with a “clamp on” type…

But, the gas port being undersized is still a possibility…
Link Posted: 3/7/2010 5:37:01 PM EDT
Thanks for the help, I moved the gas block forward about the thickness of a .5 pencil lead.
Link Posted: 3/7/2010 5:37:55 PM EDT
i had the same problem with a Noveske barrel and noveske low pro block i was using for my build. It was the intermediate gas system. It would short stroke as u mentioned, only ejecting the shell not loading the next.  I finally read a book i picked up from Midwayusa and the author recommended putting locktite around the gas block to creaet a seal around gas block and the barrel, after i did that the gun shoots great. hope this helps
Link Posted: 3/7/2010 6:08:01 PM EDT
Thanks for the INFO. I will try this and let you know how it works.
rubar01
Link Posted: 3/7/2010 6:09:37 PM EDT
What was the name of the book I would like to read it myself.
Link Posted: 3/7/2010 6:19:23 PM EDT
the book was" the ar 15 complete assembly guide". It was very helpful to me (i used it on my first build which was also the first time i had every handled an ar 15), and definitely worth the money, after all it saved my build and made it function after i spent hours tearing it apart trying to find what the problem was. there was even a detailed section on the install of a jewell trigger which i found very helpful since everyone knows jewell has the worst install directions. There are tons of pictures to help you through the process of the build. great book.
Link Posted: 3/7/2010 6:31:39 PM EDT
THANKS!!!!!!!!!!!!!!!!!
Link Posted: 3/8/2010 2:13:41 AM EDT
Before you do anything else, try shooting the rifle with only one round in the magazine. You want to determine if the bolt carrier is going back far enough to engage the bolt stop. If the bolt will lock to the rear, you most likely don't have a problem with gas pressure. If the carrier won't go back far enough, then you might have a gas pressure issue.

You should also make sure that the gas tube lines up properly with the carrier key. All you have to do is strip the carrier of bolt, firing pin and cam pin and slide it into the upper. It should slide all the way in without dragging on the gas tube.
Link Posted: 3/8/2010 8:09:04 AM EDT
Thanks for the imput, I will try this when I get home this evening.
Rubar01
Link Posted: 3/8/2010 11:45:16 AM EDT
If its lined up on the tube, then I would make it a simple fix by changing out your BC.
Link Posted: 3/8/2010 12:18:00 PM EDT
[Last Edit: 3/8/2010 12:21:32 PM EDT by M4bangr]
Don't start taking things apart or replacing things until you try some good 5.56 power ammo. The .223 ammo you are using may not provide enough oomph to send the BCG back for enough to strip off another round from the mag because of the friction created by the new parts .
Always try the easy stuff first and try what sleeper recommended with the one round in the mag.
Link Posted: 3/8/2010 4:52:31 PM EDT
I have tried Remington, Hornaday, Bitter Root, and Wolf. When I go back to the range I an going to try Winchester, Monarch and any other I can find.
Any sugestions?
Link Posted: 3/8/2010 6:45:49 PM EDT
Originally Posted By rubar01:
I have tried Remington, Hornaday, Bitter Root, and Wolf. When I go back to the range I an going to try Winchester, Monarch and any other I can find.
Any sugestions?


I would try XM193 or Q3131.
Not familiar with Bitter Root, but I believe all those you mention are .223.
Once you run several hundred 5.56 rounds through it to loosen it up, then go back and try the lesser powered .223.
Link Posted: 3/8/2010 7:13:12 PM EDT
My opinion you have tried enough ammo types. When I see Bushy BC I raise a flag as I have seen enough of them with key gas problems. Maybe a problem ––-maybe not the problem . Read both pages of this also and good luck.
http://www.ar15armory.com/forums/short-stroking-t52200.html
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