Try reading this ,rather than Me telling You various options
y)https://www.silencercentral.com/blog/how-to-fix-your-ar-15-when-its-not-cycling/
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55’s not fully cycling in 223 Wylde 18”
- Thread starter KneverKnew
- Start date
Try reading this ,rather than Me telling You various options
y)https://www.silencercentral.com/blog/how-to-fix-your-ar-15-when-its-not-cycling/
Will do thanks!Try reading this ,rather than Me telling You various options
https://www.silencercentral.com/blog/how-to-fix-your-ar-15-when-its-not-cycling/
Here's another reliable port sizing spec sheet . IF You ever order a barrel or upper ,You can specify what port size you'd like .
When I order a barrel I always have a smaller port size ,that way I can drill it myself so as to make exactly what I want .
Largest port size I've ever had to drill for an AR15 22.5" Rifle is 0.094" it was sticky at 0.092". On 98% of all MY 20" barrels run 0.088- 0.092" . My 16" barrels are mid length and run 0.076" ,0.078" and 0.82" and I've got a slew as well as variety of manufacturers of those .
When I order a barrel I always have a smaller port size ,that way I can drill it myself so as to make exactly what I want .
Largest port size I've ever had to drill for an AR15 22.5" Rifle is 0.094" it was sticky at 0.092". On 98% of all MY 20" barrels run 0.088- 0.092" . My 16" barrels are mid length and run 0.076" ,0.078" and 0.82" and I've got a slew as well as variety of manufacturers of those .
Did anything in particular jump out at You within context of cycling issues ?. Personally I've seen less than 0.01% being gas rings , then again one never really knows ,IF they don't look or do the bolt stand carrier test .
Removing the bolt carrier group and extending the bolt, and placing or standing the bolt face against a flat bench-top , counter surface you can get an idea if it is time to replace them. In doing this your bolt carrier group can do one of three things. It can fall straight down, collapsing onto the bolt ,Not good they're worn out . Absolutely should be replaced . IF they hold the carrier , NO problem ,simply drop a little lube on them and reassemble the BCG ,check the Viton O ring for any tears and replace if necessary .
IF the carrier slides slowly down onto the bolt ,rings are wearing lube them reassemble and Buy New Rings ASAP. IF Carrier stays in position and doesn't slide onto the bolt , You're Golden simply lube and reassemble .
Many of us Myself included , neglect to lube gas rings often enough . They are like compression rings on a piston ,should be offset to each other lubed and after XXX amount of rounds cycled ,need to be inspected and at least Lubed . The gas rings have NO particular order in which they offset .
Gas rings can certainly account for short stroking and failure to lock back on empty mag.
Fyi : If everything had been working like clockwork in one's AR's and suddenly something is amiss , Check and clear the gas port ,tube and check those Gas rings ,before screwing around with springs and buffers . Might just surprise you .
The gas rings tested out fine, zero movement on the stand test. Last time I shot they were a little dry so before my next session I will make sure they get a few drops of CLP.
There was something that jumped out at me the session before I started experiencing the short stroking issues. I was shooting some pretty close to max 5.56 loads and noticed some weird triangular shaped dents just under the shoulders of some brass. I started a thread on it here:
5.56 AR reloading: Can Anyone ID what would cause these weird triangle shaped scrape marks/dents just below the shoulder?
It doesn’t look like the same type of mark from too much lube during FL sizing. This actually has brass scraped off leaving an inverted triangle shape (most clearly seen in bottom row of bottom image). Im going to toss this brass but was curious about root cause. My guess on the root cause is...
www.snipershide.com
The consensus was that it was happening during ejection from my brass deflector. To remedy this I put a small sticky piece of velcro pad on the deflector and tried bumping my h2 up to an h3. My first session shooting with H3 caused short stroking so I figured it was the extra weight from the H3 so in the next session after that one I bumped it down to h1 and still had short stroking. This is where I'm at now and scratching my head wondering wtf.
I haven't seen those triangle marks since that one session and after putting the velcro over the deflector.
At this point I'm pretty much going to do what you suggested. I'm back to the original setup that worked fine without a single issue for well over 1K rounds -->super 42 spring with h2 buffer. Hopefully within the next few days I will get out to the range to test this setup on some black hills 77gr OTM factory loads with a garmin chrono to get a solid baseline and velocity readings. If I get short stroking I also have the stock carbine buffer weight (all steel weights) and spring that came with the Aero M4E1 lower that I can swap in while stil at the range to see if it helps.
If I still get short stroking with the carbine buffer weight & weaker spring I will check the gas port, tube, etc. when I get back as you suggested. I also have some compressed air in a can I can blow down the tube to check for flow issues. If nothing jumps out during all of that I will call Geissele.
Thanks again for all the help/feedback.
I have not checked them but thats a good call out. I think they should be at least 40 in-lbs right?
I should have elaborated a bit more on that last point. Take the proper sized driver and give it a good turn like 40-50 in lbs. I’ve seen broken screws where the head is held in by the staking and appear good with a visual inspection.
Some folks clearly didn't read but one thing I read you did mention is that you have an 18" barrel with a RIFLE length gas system.
That means you have less time for your gas pulse. That will tend to be under gassed if having an issue.
Some folks suggesting an adjustable gas block are kinda wasting your time as an adjustable block will not give you more gas.
A simple thing you can also try is swapping parts from rifles you know are functioning well. For example you said the other rifle shoots the same ammo with no malfunctions. Tale the BCG out of that rifle and see if it runs. If it does, swap just the carriers etc. Then you can narrow down the offending part.
Otherwise if you are running the lightest buffer already you will likely have to open up your gas port. Also check with a pin gauge that the prt is the same size all the way down. I had one under gassed rifle a customer brought me and the port was drilled to the correct size but not ALL the way through and thus a choke point was caused. Drilled it the rest of the way and it ran fine.
I will send you a link to something.
That means you have less time for your gas pulse. That will tend to be under gassed if having an issue.
Some folks suggesting an adjustable gas block are kinda wasting your time as an adjustable block will not give you more gas.
A simple thing you can also try is swapping parts from rifles you know are functioning well. For example you said the other rifle shoots the same ammo with no malfunctions. Tale the BCG out of that rifle and see if it runs. If it does, swap just the carriers etc. Then you can narrow down the offending part.
Otherwise if you are running the lightest buffer already you will likely have to open up your gas port. Also check with a pin gauge that the prt is the same size all the way down. I had one under gassed rifle a customer brought me and the port was drilled to the correct size but not ALL the way through and thus a choke point was caused. Drilled it the rest of the way and it ran fine.
I will send you a link to something.
GOOD advice , gas ports are critical areas relevant to gas tube length and as I've said NOT all powders work for correct pulse .
However IF suspect rounds run in another unit ,then start at basics and run forward . Frustrating to ME too backtrack problems .
Just got back from the range. Quick upate:
14.5” mid length super duty upper with no carbon ring.
H2/super 42 with AAC 5.56 55gr FMJ (2919 avg fps), failed to feed or lock just like before.
Carbine weight/aero stock spring fed ok but didn’t lock.
Black Hills 77gr OTM (2621 avg fps) with carbine weight/stock spring fed and locked without issue.
22.3 to 24.3ge TAC with 77gr SMK @2.246” fed and locked without issue.
Seems like the swap to carbine weight and aero stock spring fixed all the issues except no lock back when using cheap plinking 55gr ammo
I'd have to suspect AAC powder selection as for weak gas pulse ( similar to those Turan M193's that fail to function ) and the only way that could be easily confirmed is , running a mag of those in someone Else's platform with a known larger port and determine if that is the primary culprit .
I'd be most curious if Your Super Duty ran PMC 55's ,without issue ??.
In MY experiences and there limited A1 and A2 models ,never had short barrels . An under gassed gun fails to cycle ,short strokes jambs or does erratic ejection patterns . An over gassed gun primarily slams crap as tries to extract cases prematurely ,suffers from feeding to ejection lock back issues . A test for that is to run full magazine ,then a magazine with #1 round ,does it act the same ?. IF so it's probably over gassed .
On short barreled weapons ,I'd prefer a larger port and an adjustable block , You can fix stuff but with a undersized port one is screwed or time to upgrade . Drill hole and get a Good adjustable block .
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Hmm I don't think I've ever run PMC 55's through it but the AAC 55's (and all other 5.56 plinking 55 FMJ's including Federal and IMI) ran fine with the H2 buffer when I wasn't whacking the carbon ring down as much. I'm trying to think what else I am doing differently but the only thing I can think of is I'm now completely removing any carbon ring after each session. I didn't even know what a carbon ring was during the first 9 months I was shooting it but I did clean the barrel with some wipeout foam after each use. If I wasn't doing handloads I probably wouldn't worry about carbon rings but I often times flirt with max pressure loads (mk 262 clone loads) and I don't want the added risk with temp swings, etc..
Since I now have a couple thousand 5.56 rounds fired on this upper the gas system (rings, etc.) are still in spec but slightly more worn/less efficient compared to when brand new. That might explain why I was able to use initially use the H2 buffer when the gun was brand new/without any carbon ring. Who knows though....
At least now I know the carbine weight + stock Aero spring will feed with pretty much any type of ammo with or without a carbon ring present and worst case it won't lock back on the really weak plinking stuff (which I only really use when at the range). My home defense mags are loaded with Black Hills 77 OTM's.
OVER GASSED ; Carbon rings are tell tail signs . I borrowed the below from Tactical ** . One has to take this in context ,as in the ammo used will properly cycle ,provided gas issues are resolved . ( IN MY case Turan WON'T cycle in anything ,yet everything else does . So although ammo is GOOD ,as cases are and accurate ,I'll NEVER use it in an AR platform ) .
**
Because the brass isn’t ready, your AR could suffer feeding and ejection issues, carbon buildup, excessive recoil, and other issues.
One way to diagnose an over-gassed AR is to assess your ammo for gouges at the base of the cases.
Another method is the one-round test. Try running the gun with a full magazine and then switch to a mag with a single round.
If the gun behaves the same with both magazines, it’s probably over-gassing.
I definitely just found the root cause of the short stroking problem. I finally got around to field stripping the gun/bolt since my range session on Friday and tested out the gas key screws to see if I could break them loose at 30 in-lbs for a general test. One of them was fine but the other I barely touched and it came loose with some amount that was way less than 30 in-lbs. I have a spare brownells complete bcg with bolt so I'm gonna throw the geissele bolt into the brownell's BCG for now so it's operational and the headspace will stay the same for my handloads. I will work on the geissele BCG to re-attach the gas key properly.
You nailed it here, thanks for the reminder! It's always the last fucking place you look right? Glad I found this b/c the one screw was so loose it likely would have caused a major jam in the gun next time I shot it. Like you said, the staking still looked perfectly fine but it was barely attached......Whew...
Glad you found the issue! It’s caused me more than my fair share of head scratching before. Like you said the last fucking place you would think.
Oh definitely...in the middle of filling out a CS form/email right now. We'll see if they stick by their bulletproof guarantee or whatever it's called, it's supposed to cover defects for up to 4 years. I bought the upper in Oct 2023 so it should be covered.
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Update, Geissele customer support responded today (less than 24hrs) to my warranty request and they are going to ship a new carrier with key out to me today. Props to them on the quick response! They asked me to send back the old one so they included a return shipping label which I’m happy to do.
Good sign they asked for the failed parts return. They need to do a deep dive into the issue.
All tapped threads are a risk. In steel parts, quality controls on threaded holes and fasteners is a constant battle. So is cleaning and prep.
The torque tools also require discipline in the calibration labs and some care and skill on the part of the operators.
When they get these parts back under a microscope, there will be several places that get investigated to learn what went wrong here.
All tapped threads are a risk. In steel parts, quality controls on threaded holes and fasteners is a constant battle. So is cleaning and prep.
The torque tools also require discipline in the calibration labs and some care and skill on the part of the operators.
When they get these parts back under a microscope, there will be several places that get investigated to learn what went wrong here.
Yep, definitely a good sign for QC. I'd hope that it's not too common for gas key screws to shear off like that after only a few thousand rounds.
Here's some stats with graphs ,which certainly can benefit all of us . : Click the link below .
http://www.ar15barrels.com/prod/operation.shtml
Now for extraction, the WRONG ways.
First, too much gas(most common):
The bullet has not left the barrel yet, but it's past the gas port.
Too much high pressure gas is rushing into the carrier, causing it to move rearward faster then desired and unlock the bolt from the extension.
Pressures are still high so the cartridge case is NOT ready to be extracted yet.
The carrier's momentum continues to pull backward, but the pressures in the case actually hold in in the chamber.
This causes a hiccup in the carrier's momentum.
Depending on the severity of the timing, several things can occur:
#1 The (weak) extractor spring allows the extractor to jump over the rim of the cartridge and the bolt carrier continues rearward, grabbing the next round and causing the classic "fired case in chamber, live round behind it" FTE.
The brass shavings under the extractor usually contribute to this one as well.
#2 The extractor does NOT slip off the case, but keeps pulling.
The extractor is strong enough to RIP the rim right off the case.
Same result as above, but MORE brass shavings everywhere from ripping case rims off.
#3 The extractor does NOT slip off the case, but keeps pulling.
During this pulling, the bullet has JUST left the bore, pressures recede and the case shrinks down, allowing extraction.
The rest of the cycle goes as normal, but you have strong pull marks on the case.
Recoil will be higher than normal when the carrier is allowed to travel to the end of the buffer tube and bottom out swiftly against the end of the buffer tube.
In normal operation, the buffer just kisses the end of the tube.
Somewhere between here and the next section, we have proper operation.
Lastly, not enough gas(less common):
The bullet is out of the bore, pressure is subsided, case is extracted and on it's way to ejection.
Depending on the severity of the lack of gas, the bolt carrier may not even get the case out of the chamber before the operating spring returns it forward.
Adding more gas, the case just barely gets out of the ejection port, but the bolt grabs it on it's way forward, classic stovepipe.
Add more gas and the cartridge clears the action, but the bolt does NOT get far enough back to strip a round from the mag.
This is classic short stroking.
You have a single shot action which extracts and ejects, then closes on an empty chamber after you fire it.
In this condition, the bolt will also ride over an empty magazine and close on an empty chamber.
Add some more gas and you will reach the point where it feeds from the magazine and ALMOST works properly, but it still closes over an empty mag.
This is two things, first, poor mag springs are not pushing the follower up fast enough to catch the bolt and second, the bolt is not quite making it back far enough to catch on the magazine follower.
Add just a little more gas and you are back to proper function.
Now, take note, that a lack of gas in a rifle that was functioning fine before can be from several things:
Gas key screws poorly staked and they loosened up, allowing some gas to escape instead of doing it's job INSIDE the bolt carrier.
Gas ring gaps are aligned, gas rings missing or broken, allowing extra gas to flow past them.
Gas block/front sight base is loose, allowing gas to escape before it even gets down the gas tube.
Gas tube "mushroom" is severely worn, probably because it was not properly aligned with the gas key and gas is escaping there.
Here is a picture of a worn out gas tube mushroom:
Great stuff, thanks for sharing! This info will definitely get filed away/bookmarked. Based on that article I guess the summary re: my rig was stove piping (fucked up a few pieces of nice LC brass) and short stroking due to a loose/sheared gas key screw. I was able to get the gun running again by going to a lighter buffer weight and weaker buffer spring but as many on this thread suggested I still needed to find the root cause and not band aide around it.
It's nice Geissele is sending me a new one free of charge but I'm also investing in some spare gas keys, screws, sealant, etc. so I can repair one myself if needed.
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Let us know how it shoots with the new carrier.
Curious though, I thought you had said at one point both rifles were doing something odd. One short stroking and the other iirc would cycle but not lock the bolt back?
Curious though, I thought you had said at one point both rifles were doing something odd. One short stroking and the other iirc would cycle but not lock the bolt back?
Will do.
Sorry you might be mixing me up with the OP. I kinda hijacked this thread for a bit ha ha. I only have one 5.56 gas rifle and it has a 14.5 inch super duty upper which shot fine for several thousand round and never had a problem. Then the last two sessions I was at the range I was getting stove piping and short cycling and no lock backs with familiar ammo. When I switched to carbine buffer weight and weaker spring I was able to fix the short stroking and it was able to lock back....but something still didn’t sit right with me because it was odd that it was randomly not working anymore, and @.505gibbs suggested to check the gas key screws and that was the root cause of the problem.
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I certainly wish I'd read your original post closer as in ;
" Then the last two sessions I was at the range I was getting stove piping and short cycling and no lock backs with familiar ammo."
I for one should have paid attention to that statement ; That's a sure sign of insufficient gas and Your gun worked just fine previously !.
So through inspection of the entire gas system , is a WAKE UP call for any of us who have similar issues ,as we can assume NOTHING without verification .
Yep, I will likely check the gas key screws with up to 30 in-lbs whenever I take the BCG out for any reason. This will at least see if anything is egregiously loose and catch it earlier if it happens again. I also have a spare gas key, screws, and sealant on the way so I can fix it in a pinch if needed.I certainly wish I'd read your original post closer as in ;
" Then the last two sessions I was at the range I was getting stove piping and short cycling and no lock backs with familiar ammo."
I for one should have paid attention to that statement ; That's a sure sign of insufficient gas and Your gun worked just fine previously !.
So through inspection of the entire gas system , is a WAKE UP call for any of us who have similar issues ,as we can assume NOTHING without verification .
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