View Full Version : Arrrrr, short stroking, mateys!
Went with a few mags of Wolf to the range and a few with the IMG Guat to test out.
Used proven mags and just shot it a few weeks ago with 60 rounds of Remington rapid/regular fire. So I know the AR was working a few weeks ago. All I did was add lube to mainly the BCG in that time span.
First round of Guat - no extract. Same on second. Okay, checked shells and extractor, all looks fine. Rule that out.
Round actually extracts but nothing is fed. Changed mags to Wolf to try different mag/ammo. Failed to extract on Wolf and different mag.
Went to yet a third mag with Guat and again same thing, sometimes the shell would extract or halfway extract and jam. An observer noticed the bolt was NOT going all the way back. So now I'm positive it is short stroking.
I strip down to bolt and the gas rings were kind of lined up so I stagger them just in case. I also try to wiggle the gas key but it is staked very well courtesy of Grant. It is plenty lubed.
I assemble and go the rest of the original mag one round at a time manually working it. When I get to the last round I notice it extract this time but sure enough the bolt didn't lock back. That confirms it. I disassemble and the gas rings are kind of lined up again but I seriously doubt that is the problem since the problem happened on the first round after I checked. I stagger again and run 2 rounds through and have the same problems and no lock back on empty mag. I check gas rings again and they've stayed staggered for that quick test.
So to recap - gas rings staggered, key staked, tube looks unbent, both types of ammo failed (underpowered .223 and hot 5.56,) 3 proven mags failed, buffer spring has been used before just fine so I don't think that is it. I think everything is good to go except the gas tube. I seriously doubt gunk is inside it so I'm guessing the problem lies under the gas block. I won't have time to get to it immediately but just want to hear what y'all think.
:confused: :confused: :confused:
Thanks guys.
(DSC lower with RRA 2 stage trigger, BCM upper. I think the BCG is LMT M16 bolt. Grant would know for sure, that's what he sold me. Everything has worked fine prior to this outing using WWB and Remington. This is the very first Wolf and 5.56 I've had to run through this. EVERY single round was manually fed.)
Check your hammer pin, make sure it has not popped out and binding the hammer and check the hammer for damage. Also check your gas tube at the block and the block itself.
First thing I would do load 1 rd in a mag and fire it to see if the bolt is locking back. do that about 10 times. Then you will know for sure if your getting enough gas or not.
How many rds are on the gun.??
Wolf is KNOWN to be underpowered. Go back to white box Winchester and see what you get (or .mil ammo).
C4
Harv, less than a thousand.
Grant, I've had a grand total of 4 Wolf rounds through it. The 5.56 was definitely hotter than store bought stuff. I'm sure it wasn't ammunition caused.
Boom, checking those suggestions now. What am I looking for at the block, tightness? I assume the port would be tapped to spec since it did work before but you know what they say about assuming.
Wolf is KNOWN to be underpowered. Go back to white box Winchester and see what you get (or .mil ammo).
C4
I wouldn't say it's "Underpowered" it's just not loaded to Mil Spec, it's closer to 223 spec.
And while I may have found that Wolf is a very poor choice for hard use on hot days, I still believe that if you rifle won't cycle Wolf Ammo, then the rifle is to blame, not the ammo.
Dragon 2 Zero
09-04-06, 15:09
What am I looking for at the block, tightness? I assume the port would be tapped to spec since it did work before but you know what they say about assuming.
You are looking for evidence of gas leaks - Carbon buildup.
Does anyone know which direction I need to go to tap the FSB pins out? I've pounded from the left side but I'm kind of babying it until I can figure out for sure. :D
ETA: I skimped on the soft love and pounded the pin from the left side. Finally got the pins out with some finessin'! How do I go about getting the gas tube off and moving the FSB forward?
ETAII: Removed gas tube easy enough. The front hole has a pattern of carbon around it that is very uneven. Assuming the roll pin side is 12 oclock there appears to be carbon eminating from 5 oclock. Methinks something is loose or what?
ETAIII: Moved the FSB pretty easy. Taking pictures now and will edit in in a few minutes.
ETAIV: Pictures below. I have higher quality pics but these should suffice.
http://www.razoreye.net/pictures/gasblock1.jpg
http://www.razoreye.net/pictures/gasblock2.jpg
http://www.razoreye.net/pictures/gastube1.jpg
http://www.razoreye.net/pictures/gastube2.jpg
http://www.razoreye.net/pictures/gastube3.jpg
Bump for very large pics added above. :D
ETA: Sized down. ;)
Well, I was hoping that my first problem with an AR could be fixed here but I guess not. I did take pictures for Boom to help me out... :(
Your gas tube looks fine to me. You are more than welcome to send me your upper and I will look at it.
I would suggest however that you first go back to the ammo that you know worked well for you and try it again. If the weapon runs with that ammo then I would say that there is nothing wrong with the weapon.
C4
Your gas tube looks fine to me. You are more than welcome to send me your upper and I will look at it.
I would suggest however that you first go back to the ammo that you know worked well for you and try it again. If the weapon runs with that ammo then I would say that there is nothing wrong with the weapon.
C4I will. Let me test everything over again before I send anything back. I have put a little bit of ammo through it and I thought everything was perfect. It may just be this ammo as this is new to my M4. I will go back and try some Rem or WWB (if I can find any!) It won't be until the weekend, but at least the gas port looks okay.
:)
BravoCompanyUSA
09-06-06, 21:39
Some general info:
Short stroking (Failure to cycle)
Short stroking on an AR rifle is when the bolt carrier group does not cycle far enough to the rear to be able to strip a round from the magazine and chamber the next round. After firing a round, you will notice that the bolt is closed on an empty chamber, thereby forcing you to manually cycle the rifle to feed the next round. This occurs when there is an issue with the gas system.
To see if you have a short stroking problem and not a “Failure to Feed” problem, please perform this test first (assuming your bolt catch and magazine is functioning properly). Insert one round into a magazine that you know to be performing well. Insert the magazine into the magazine well, pull the charging handle to the rear, then release the charging to load the round into the chamber. Safely discharge that round. After the round has been fired the bolt should automatically be locked to the rear by the bolt catch and the empty magazine. If the bolt is closed on the empty chamber, then it did not travel far enough to the rear to be held by the bolt catch, and your rifle has short stroked.
Short stroking is a symptom of a problem with the gas system in the rifle. There are 7 parts of the AR gas system. In the upper receiver group, you have the barrel (gas port), front sight base, and gas tube. In the bolt carrier group you have the gas key, the carrier, the bolt, and the gas rings.
Assuming the rifle was running correctly previously (in the exact configuration it is currently) The following is a basic trouble-shooting checklist.
1) Ammo issue ? Commercial ammo does not run as hot as Milspec ammo, and some lots of commercial ammo may not be strong enough to cycle the weapon. Try a completely different type of ammo. If the weapon works correctly then you may have some bad ammo. This is becoming a more common problem with some of the low cost imported ammo, especially with milspec sized gas ports.
2) Lube and clean the rifle. Pull out your GI manual and properly clean the weapon. As a note, a little bit of dirt and carbon should not stop the proper cycling of your rifle.
3) Check the carrier (gas) key. If the carrier key is loose, the gas system will not hold enough pressure to fully cycle the weapon. Try a different carrier that you know to be working in another properly functioning weapon. If the weapon runs well with the other carrier, you may have an issue with your carrier key. The carrier key bolts should not be loose. It should be staked from the factory. Check to make sure the bolts securing the key did not rotate past the staking. The bolts should be torqued to 35-40 in/lbs.
4) Check the gas rings. (or just go ahead and change them – they are very inexpensive) Mythbuster: The gaps in the gas rings do not need to be staggered. I know we were all taught otherwise in recruit training, and yes I know it says they must be staggered in the GI manual. But this is a myth. As a note; it will not hurt the system to stagger the gaps in the rings, but if this single change makes the difference – you need new gas rings ASAP. Inspect the rings, make sure there are 3 of them, and that they are installed properly. Disassemble the carrier group, insert the bolt into the carrier, and hold the carrier vertically in the air. The bolt should not fall out of the carrier.
5) Change the gas tube.
I found a guy at the range using that ammo and was having FTE issues every round. I pulled apart his upper and Bolt and found that his extractor was way too easy to push in. I swapped the spring out with a blue insert and spring from an old DPMS spare spring kit. Fixed his problem and he was as happy as a puppy with two peters. It was a rifle- did I use the right color? Black is for Carbines, right?
K.L. Davis
09-06-06, 22:06
It is hard to tell from the pics... but it does look like some carbon tracking and etching of the gas tube, down around 4 o'clock in the picture. While it may not be much, every bit counts -- I am a stickler for this... ANY leaking is not right.
What receiver extension tube, carbine or rifle? Recoil/Op spring? Buffer?
Is that an LMT "enhanced" BCG?
It is hard to tell from the pics... but it does look like some carbon tracking and etching of the gas tube, down around 4 o'clock in the picture. While it may not be much, every bit counts -- I am a stickler for this... ANY leaking is not right.
What receiver extension tube, carbine or rifle? Recoil/Op spring? Buffer?
Is that an LMT "enhanced" BCG?
Let's see, that is carbon you spot around the 4/5 oclock position. How would you fix even that little bit?
Carbine rec. ext. tube. Ummm, the spring and buffer came with it. 4 position stock (I know, el cheapo, I'm working on the CTR.) so I'm not sure but I assume Centerfire Systems gave me the correct stuff.
Suicide, interesting theory. Did you fix the problem or just patch a deeper problem with that fix? It may be as simple as that since most the shells did NOT even extract. The extractor itself looks fine but maybe the spring is not good. Each casing had marks of the extractor catching. In fact, the observer that helped me said he saw the shell extract halfway but get rechambered. The marks on the casing confirm this, which is why I believe there is too little pressure for the bolt to get even past the midpoint of the carrier. If it turns out to be a BCG problem, I might just send it back to Grant, if he wouldn't mind fixing it for me.
Let's see, that is carbon you spot around the 4/5 oclock position. How would you fix even that little bit?
Carbine rec. ext. tube. Ummm, the spring and buffer came with it. 4 position stock (I know, el cheapo, I'm working on the CTR.) so I'm not sure but I assume Centerfire Systems gave me the correct stuff.
Suicide, interesting theory. Did you fix the problem or just patch a deeper problem with that fix? It may be as simple as that since most the shells did NOT even extract. The extractor itself looks fine but maybe the spring is not good. Each casing had marks of the extractor catching. In fact, the observer that helped me said he saw the shell extract halfway but get rechambered. The marks on the casing confirm this, which is why I believe there is too little pressure for the bolt to get even past the midpoint of the carrier. If it turns out to be a BCG problem, I might just send it back to Grant, if he wouldn't mind fixing it for me.
As I said, I don't mind looking at it for you, but would first run some quality ammo through it and see what you get.
C4
Nine times out of ten when I encounter someone at the range who has an AR that is short stroking but used to run fine, a shot of lube gets it running again. Usually their lube has dried up or run off leaving gunk behind.
1) I'd try *drowning* it in a CLP-type lube (Rem-oil works if you can't find anything else). You can figure out exactly where you need to apply lube and how much later, for now, just hose down the entire BCG and inside of the upper to eliminate friction as a variable.
2) Which buffer are you using? Try a lighter buffer if possible.
3) Do you notice any binding when you pull the charging handle manually
As I said, I don't mind looking at it for you, but would first run some quality ammo through it and see what you get.
C4
Sorry, didn't mean to imply you wouldn't. Thanks.
Griz,
1.) Yes, I Slip'd2000 it up.
2.) Whatever came with 4 pos stock. I'm not sure.
3.) No.
I plan on going Sunday so I'll update then. Thanks fellas.
Alright, things I've tried.
Bought Rem 55 gr.
Single round, proven mag = failure to stay open (FSO)
Repeat (3x)
Used one round of Wolf and one round of IMG each resulting in an FSO.
<5x Total with one round in mag test.>
Tried 2 rounds because each successfully extracted. 2 rounds IMG seperate mag gave 2 FSO/FTF. Same with Rem (yet another mag) except a FTE/FTF.
Changed out buffer springs, repeat mag test and had a FSO with Rem. Lubed the hell out of the BCG, moved the hammer pin and reseated and lubed and 2 FSO with 2 rounds of Rem one at a time.
I'm still not sure what "type" of buffer I have but it came with the 4 pos stock and worked before.
So ammo seems to check out, as well as mags, springs, lube, etc.
The only thing I can conclude is the gas port or BCG. I will try to get a friend to bring his M4 next time so I can swap BCG and do some tests. If that fails then we know what the problem is and I can send back to Grant. I'll try to do this test asap but our work schedules conflict so I don't know how soon that can happen.
I did notice that the 5.56 ammo tended to extract FORWARD if that means anything. The .223 tended to stay 90 degrees or back. I don't think the bolt went all the way back even once.
Update:
I just got done testing using a friend's BCG. I don't have his upper but this test points to the BCG as the problem.
His carrier is of the AR15 kind, less weight, cut out - you know what it is. Anyways, I tried mine first with one round and good mag and still short stroking. Repeated three times. Slapped in his BCG and voila! The mag hold open test worked every time and I went through two mags of different ammo. I used his BCG minus his bolt and used my bolt in it. Still worked. Used my BCG minus my bolt and used his bolt in it. It short stroked.
This all leads me to the final conclusion that my key somehow loosened up (although it appears it hasn't moved and is still tight as a tick) OR the M16 carrier isn't working right. Maybe the slight gas leakage in the above pics plus a heavier carrier means it won't cycle all the way and switching out springs might fix it??
In any case, Grant I am sending the BCG back to you. Would you like me to go through the hassle of sending you the whole upper as well or not? I ask that you test out my BCG first when you receive it and then do your fix (I assume that's how you do it but I just want your feedback on the issue when you get it.) Thanks so very much.
:D
Update:
I just got done testing using a friend's BCG. I don't have his upper but this test points to the BCG as the problem.
His carrier is of the AR15 kind, less weight, cut out - you know what it is. Anyways, I tried mine first with one round and good mag and still short stroking. Repeated three times. Slapped in his BCG and voila! The mag hold open test worked every time and I went through two mags of different ammo. I used his BCG minus his bolt and used my bolt in it. Still worked. Used my BCG minus my bolt and used his bolt in it. It short stroked.
This all leads me to the final conclusion that my key somehow loosened up (although it appears it hasn't moved and is still tight as a tick) OR the M16 carrier isn't working right. Maybe the slight gas leakage in the above pics plus a heavier carrier means it won't cycle all the way and switching out springs might fix it??
In any case, Grant I am sending the BCG back to you. Would you like me to go through the hassle of sending you the whole upper as well or not? I ask that you test out my BCG first when you receive it and then do your fix (I assume that's how you do it but I just want your feedback on the issue when you get it.) Thanks so very much.
:D
Please send me the complete BCG and upper.
C4
Please send me the complete BCG and upper.
C4
Being a cheapskate, I wanted to see if I could fix it myself first before ponying up cash for shipping. I tried backing out the top screw with a screwdriver because I didn't have the right hex key. It turned loosely in there and I realized the screw must have broken off and there was my leak. So I try to take the back screw out and I strip it thereby ****ing everything up. So now I take a dremel and cut the two stake lines deeper so I can put a screwdriver in there. Well, the cut was crooked so the screwdriver kept slipping and the metal seemed to have melded to eachother on the cuts. Cut a little more, nothing, cut perpendicular for a phillips, nothing. So I went near the base of the carrier key and cut horizontal so I could cut the head off the screw. Once I did that it took a little prying and the key popped off. Thankfully, the two remaining pieces of the screws backed right out by hand and now all I have to do is buy a new key and non-faulty screws.
Talk about a pain in the ass. I'll try to post pictures later. :D
Robb Jensen
10-23-06, 11:14
Being a cheapskate, I wanted to see if I could fix it myself first before ponying up cash for shipping. I tried backing out the top screw with a screwdriver because I didn't have the right hex key. It turned loosely in there and I realized the screw must have broken off and there was my leak. So I try to take the back screw out and I strip it thereby ****ing everything up. So now I take a dremel and cut the two stake lines deeper so I can put a screwdriver in there. Well, the cut was crooked so the screwdriver kept slipping and the metal seemed to have melded to eachother on the cuts. Cut a little more, nothing, cut perpendicular for a phillips, nothing. So I went near the base of the carrier key and cut horizontal so I could cut the head off the screw. Once I did that it took a little prying and the key popped off. Thankfully, the two remaining pieces of the screws backed right out by hand and now all I have to do is buy a new key and non-faulty screws.
Talk about a pain in the ass. I'll try to post pictures later. :D
Doh! If you tired of WECSOG'n it send the the carrier and for the cost of the key, screws and return shipping I'll install and stake with a MOACKS. :D
Doh! If you tired of WECSOG'n it send the the carrier and for the cost of the key, screws and return shipping I'll install and stake with a MOACKS. :D
RESOLUTION: Sent off my BCG to gotm4 who fixed it and upgraded springs/extractors free of charge (I hope I covered enough for the parts) and replaced my carrier key. The MOACKS looks beautiful and I finally got to try it two weeks later. Shot 300 rounds through it today of Wolf and Guat, all worked flawlessly.
I had two Wolf with light primer strikes but both those times I was trying to bump fire and I think I absorbed too much recoil by hanging onto it so loose. Both rounds shot off fine when rechambered and shot correctly.
Thanks gotM4, class act guy! :D
PS - @50 yards: Wolf shot minute of chest, Guat shot minute of plate from a crouched position. Both groups were a bit left due to messing with the sights.
Robb Jensen
11-26-06, 20:20
You're welcome dude. Glad it worked out for you.
Doh! If you tired of WECSOG'n it send the the carrier and for the cost of the key, screws and return shipping I'll install and stake with a MOACKS. :D
gotM4,
Pardon my noobness, but what does the acronym "MOACKS" mean?
uxb
Robb Jensen
12-08-06, 11:27
gotM4,
Pardon my noobness, but what does the acronym "MOACKS" mean?
uxb
MOACKS=mother of all carrier key staking tool. It's a carrier key staking tool made by Master Gunsmith Ned Christiansen.
Very informative-fixed the same exact problem on mine too-thx very much for the explicit explanations.
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