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1/25/2007 11:10:19 AM EDT
Just got my upper back from AR15.barrels... Started out as a 20" h-bar, I had it shortened to 14.5 , midlength gas installed and re-profiled ... and the damn thing keeps short stroking "First round goes off bolt does not go back far enuff to load a new round from magazine.....

Complete setup is Complete CMMG upper , DPMS lower with RRA part kit , KNS Pins , ACE ARFX Rifle stock with standard buffer tube,spring and buffer.

I tried the following all resulting in getting me nowhere as far as fixing the problem:

Checked for gas tube leak
Checked carrier key
Checked gas rings
Check buffer tube and spring for problems
Checked barrel for problems
Checked upper for a bur or something in the receiver to cause a hangup
Checked KNS Trigger/hammer pins "Problem occurs with stock pins , KNS Gen 1 and KNS Gen 2" so it's  not the pins
Took apart trigger assembly checking for grit , metal shaving , spring problem and found nothing
Tried 5 different ammos both Military and commercial
Tried 5 differant mags
Tried a friends bolt/carrier
Tried the 1 round in mag , see if it shoots and locks open on empty mag idea and that failed

And the weather is 72 outside with almost no humidity whatsoever.
1/25/2007 11:12:30 AM EDT
[#1]
this probably wont help much, whats the diameter of the gas port hole?
1/25/2007 11:19:33 AM EDT
[#2]
Carrier key dragging on the gas tube?
1/25/2007 11:25:40 AM EDT
[#3]
don't know the diameter, was told "standard".


and no, nothing feels atall like it's dragging... EVERYTHING seems fine but obviously is not :-x
1/25/2007 11:26:30 AM EDT
[#4]
don't know the diameter, was told "standard".


and no, nothing feels atall like it's dragging... EVERYTHING seems fine but obviously is not :-x

tried calling randall @ ar15barrel a lil bit ago got no answer "probably working on a barrel or somthing and can't get to the phone" I'll try again in a little while
1/25/2007 11:28:47 AM EDT
[#5]
You might have a burr on the new gas port drilled into the barrel. This would impede gas flow causing short stroking. Have you took a peak down the barrel?
1/25/2007 11:48:30 AM EDT
[#6]
Brushed barrel, cleaned it before and after shooting with current problem.

all seemed fine :-\

ONly thing I havn't tried now hat I think about it is taking a gas tube cleaner and cleaning out the gas tube..
1/25/2007 11:51:33 AM EDT
[#7]
What ammo are you using?
1/25/2007 1:19:21 PM EDT
[#8]
military ss109 , winchester white box , remington umc , hornady tap , and some other remingtons unknown what they are "threw away the box"
1/25/2007 5:16:29 PM EDT
[#9]
no ideas ?

wasn't dirty gas tbe, cleaned the hell out of it with spray-brake cleaner and gas tube cleaners
1/25/2007 5:20:02 PM EDT
[#10]
Front Sight Base not aligned with the barrel gas port?
1/25/2007 5:22:12 PM EDT
[#11]

Quoted:
Just got my upper back from AR15.barrels... Started out as a 20" h-bar, I had it shortened to 14.5 , midlength gas installed and re-profiled ... and the damn thing keeps short stroking




Did this weapon ever function?  We need to know if it worked before it was sent out.
1/25/2007 7:18:37 PM EDT
[#12]

Quoted:

Quoted:
Just got my upper back from AR15.barrels... Started out as a 20" h-bar, I had it shortened to 14.5 , midlength gas installed and re-profiled ... and the damn thing keeps short stroking




Did this weapon ever function?  We need to know if it worked before it was sent out.


yup weapon worked great for 800 rounds, got tired of lugging 20" on 4mile hikes had it lightened and shortened.

"there is no front sight base, pure free float with rail mounted sight and rifle length FF handguard/rails"

not bombing AR15barrels.com other than this short stroke problem his work is great but wth is going on...wish he'd answer his phone though have tried atleast 30 times :-\
1/25/2007 7:27:46 PM EDT
[#13]
Wow I have never herd of it short stroking on a 14.5. Usualy you get that with short barrels like 10" or 7" . In those cases a piggy break fixed the problems. Sounds like it needs the gas hole opened up a little. Tag for outcome.
1/25/2007 10:55:03 PM EDT
[#14]
well damn, I guess it is leaking in the gas-block... if you put a few drops of oil, or use a spray cleaner it oozes out all over under/around the gas block...

I doubt this is normal?
1/26/2007 3:44:43 AM EDT
[#15]
what brand of gas block is it?    

Not what you want to hear but if you keep cleaning that area the carbon will get cleaned off that area and prevent it from making a good seal.

you may want to try a new gas block and tube, make sure it is lined up properly and shoot it again.  It would be worth it to take it off just to see if there is any obstruction in the gas hole anyway.
1/26/2007 4:03:43 AM EDT
[#16]

Quoted:
what brand of gas block is it?    


Photos might help too.

Some leaking is normal around the gas tube/FSB or gas block. Oil will seep from this area if sprayed down the gas tube and left in there. It’s not a “air tight” seal, not yet anyways. Because as mentioned above, through normal use carbon build up will begin to collect where the gas escapes eventually sealing off the gas system. But the rifle should cycle long before this carbon build-up begins to form.

And if you can’t reach Randall over the phone I would suggest a IM. He’s a stand-up guy and is frequently on line here. He’ll square you away.
1/26/2007 6:42:21 AM EDT
[#17]

Quoted:

Quoted:
what brand of gas block is it?    


Photos might help too.

Some leaking is normal around the gas tube/FSB or gas block. Oil will seep from this area if sprayed down the gas tube and left in there. It’s not a “air tight” seal, not yet anyways. Because as mentioned above, through normal use carbon build up will begin to collect where the gas escapes eventually sealing off the gas system. But the rifle should cycle long before this carbon build-up begins to form.

And if you can’t reach Randall over the phone I would suggest a IM. He’s a stand-up guy and is frequently on line here. He’ll square you away.



Well yeah, I know he's good everything seems fine yet somthing is wrong... maybe there is a metal shaving or somthing blocking the tube somwhere, or a f-ed up gas tube that was made wrong...
1/26/2007 6:49:59 AM EDT
[#18]
It would really help to have a pic of your set up. You never mentioned what type of gas block you have.

I believe you have two options at this point:

1) Contact AR15 barrels with your concerns. And wait for his reply or.........
2) Disassemble your gas block and gas tube and check for obstructions.
1/26/2007 6:55:56 AM EDT
[#19]
First thing I would do is try and shoot it as many times as you can.  DON'T CLEAN ANYTHING. Pull the gas block off and check to see if you have any kind of carbon ring that is misaligned anyway around the gas hole.  From there if you can't find anything I would replace the gas block and gas tube.

Pics would help a lot too.
1/26/2007 6:59:30 AM EDT
[#20]

Quoted:
First thing I would do is try and shoot it as many times as you can.  DON'T CLEAN ANYTHING. Pull the gas block off and check to see if you have any kind of carbon ring that is misaligned anyway around the gas hole.  From there if you can't find anything I would replace the gas block and gas tube.


I’m tending to think misaligned gas block or gas system obstruction as well.
1/26/2007 11:30:56 AM EDT
[#21]
It's just a YHM low profile gas block, I got from Bravo Company... or was it Del-ton ? "I'd have to check the receipt"

Can't dissasemble the gas block lol, I didn't want to have to buy the wrenches and crap for the handguard so I just had Randall@ Ar15barrels install everything :-x

Got ahold of AR15barrels via email, got 1 reply 15 hours ago... waiting on 3 more

will post pics soon, my damn camera batteries or dead the lens won't evan come out "takes 1 1/2 hours to charge"
1/26/2007 2:20:09 PM EDT
[#22]
***Found the problem!!!!*** but I can't get to it to fix it right... the gas block was semi loose, managed to lightly tighten 1 and 1/2 of the 2 screws and it worked for 10 rounds then worked loose again....and the problem started over again... How the hell do you get into the gas block with a YHM lightweight rifle length FF rail installed + the endcap he glued in...
I need to get the endcap or rail off and apply some blue loctite to the gas-block screws "but then how would I re-aling the forend correctly for rails to line up?"


I didn't by any of the tools at the time because I was having you install everything for me and I figured why spend $90 on tools..
I always buy pre-assembled uppers so I have no access to an action block so now it bites me in the ass >_<
1/26/2007 2:59:24 PM EDT
[#23]
Sorry I have no experience with YHM FF Forearms.

Once you get that thing where you want it, use RED locktite, not blue.  Just make sure you absolutely have it correct because you will need a torch to heat up the screws to get RED locktite off.
1/26/2007 3:10:40 PM EDT
[#24]
Thanks everyone for all the support, problem solved and fixed!

I drilled 2 small holes in the bottom of the FF rails to gain access to the screws. I then removed the screws 1 at a time blue loctited them and tighten them down until my fingers turned blue. After it set, I then ran 120 rounds of 5 types/brands including wolf with NO problems atall !!!

like I said earlier AR15barrels "Randall Rausch" work is top notch!!! it was the gas blocks fault the damn screws probably worked there way lose on shot #1 and then got worse.

1/26/2007 3:12:00 PM EDT
[#25]

Quoted:
Sorry I have no experience with YHM FF Forearms.

Once you get that thing where you want it, use RED locktite, not blue.  Just make sure you absolutely have it correct because you will need a torch to heat up the screws to get RED locktite off.



I have no red loctite left, for now I'll use blue "since it's removable" give it a few days make sure nothing happens "I Doubt it will" then I'll use Red
1/26/2007 3:16:22 PM EDT
[#26]
My reason for using pinned gas blocks only.
1/26/2007 3:22:10 PM EDT
[#27]
I Guess it's in the correct spot, since it moved left/right a little and I put it all the way left "which when looking down the barrel looks straight" and it's working perfect
1/26/2007 3:30:49 PM EDT
[#28]
Glad you got it working.  The lesson here is also to provide as complete a description as possible of the weapon when posting the problem.  As good as your original description was, it tended to list parts that you had already checked rather than areas you might have overlooked.

Quib got it in about 4 posts but probably only would've taken one post had the original post mentioned YHM set-screw gas block or included a picture.
1/26/2007 3:47:43 PM EDT
[#29]

Quoted:
Quib got it in about 4 posts but probably only would've taken one post had the original post mentioned YHM set-screw gas block or included a picture.



Actually I got it on post #3.  

But yes, accurate descriptions of the weapon and accessories mounted always help, pics are often better.
1/26/2007 5:00:06 PM EDT
[#30]

Quoted:

Quoted:
Quib got it in about 4 posts but probably only would've taken one post had the original post mentioned YHM set-screw gas block or included a picture.



Actually I got it on post #3.  

But yes, accurate descriptions of the weapon and accessories mounted always help, pics are often better.


yup, that probably would have helped you guys in helping me :-x.
went with YHM parts on this build since they are good stuff for the low price. good enuff to be a beater gun "general use"  

building a 18" SPR on the side and my POF "when it ships" will be the babied one :-x
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