AR15 Build issue. gas?

[v0lcom13sn0w]

Hey guys,
First and foremost, i have built many AR15 type rifles and am no stranger to them at all. i have never had any problem with any rifle i have ever built. i have mainly built rifles with 16" barrels with carbine or midlength gas systems and a couple short barrel pistol builds with pistol gas systems. i am a very mechanically inclined person as i work with my hands and tools as a professional automotive technician. i would consider myself one with a bit of common sense but i will admit i dont know everything.
that being said, i have an issue with a recent "heres a bunch of parts i bought, build my rifle for me" super bubblegumin rifle length build i did for a friend. all parts are what i consider to be of top quality but, it does not cycle (short strokes) with .223 or 5.56 ammo. it is a 223 wylde 18" ballistic advantage SPR barrel with a rifle length gas system and carbine buffer tube with a carbine weight buffer installed currently. i have double and triple checked the gas block(adjustable), checked the gas rings, gas key, gas tube...everything. everything except the actual size of the gas port. my question is, should this gas port be in spec, is it possible that the dwell time is just too short for this setup and i may need to drill/ream the gas port(last resort,honestly) to a larger size beyond "spec" ?(i believe its .093-.096?) i may be wrong but i have considered swapping to a midlength barrel to prove this theory of mine. would like to know any thoughts? ideas? thanks!

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[Joe13]

Saved this from another thread.

Best of luck!

 

[Boboclown]

Short-stroking can happen for various reasons. 1) Crappy magazines. 2) Overgassed. 3)Buffer too heavy. 4) Not enough gas. Etc etc.

If it ejects, big thing is to check where it lands. Every detail helps.

If undergassed, if you're using the lightest buffer you can, check other things. Might need new gas rings or something. Could be something wrong with the gas block.

 

[Member 34319]

My guess would be port or port size. Sometimes I would just go back and ream the port hole with the same size bit and it would do the trick.

I'd also visually inspect everything where has goes. Make sure that the bolt is assembled correctly, that the carrier is actually drilled. These things are usually overlooked do to it being name brand or high end, but sometimes even the big names mess up.

It does sound like a gas issue though. If it were me, I would go one size bigger on the port till it cycles.

 

[Iceman04503]

Is the gas tube the right length?

 

[v0lcom13sn0w]

Is the gas tube the right length?

yes it is. as a matter of fact, the original one he gave to me was too long. it was over 16" long. i had to go to curts to get another one.

 

[v0lcom13sn0w]

View attachment 303519

Saved this from another thread.

Best of luck!

thanks joe!

 

[v0lcom13sn0w]

i swear its an addiction buliding these things. i can put a rifle together in less than 30 min. and YES most of them function. -my buddies is a different story. LOL. i must say though, his will be pretty BAD-A$$ when it starts to work.

 

[Boboclown]

So I'm guessing the ejection is between 4 and 6?

 

[v0lcom13sn0w]

So I'm guessing the ejection is between 4 and 6?

4 and 6 is where i like to see it i will report my findings from the range hopefully this weekend

 

[Boboclown]

Between 4:30 and 6 would mean its undergassed. Between 3 and 4:30=Gas is not an issue. Between 12-3 is overgassed. Anything else, check if it the brass isn't bouncing off of something else.

 

[jc79]

I recently put together an upper with the exact same barrel, but I ordered a Ballistic Advantage gas block and gas tube to go along with the barrel.

5.56, 223, and my handloads all cycle perfectly fine with a standard weight carbine buffer. That said I don't believe there should be any issues with the amount of dwell time for this barrel. As others said maybe check the gas port size if you're sure the gas block and tube are good.

Best of luck getting it sorted out.

 

[v0lcom13sn0w]

I recently put together an upper with the exact same barrel, but I ordered a Ballistic Advantage gas block and gas tube to go along with the barrel.

5.56, 223, and my handloads all cycle perfectly fine with a standard weight carbine buffer. That said I don't believe there should be any issues with the amount of dwell time for this barrel. As others said maybe check the gas port size if you're sure the gas block and tube are good.

Best of luck getting it sorted out.

thanks, he is going to be stopping by at some point this weekend and I'll hopefully get a chance to mess with it.

 

[v0lcom13sn0w]

alright guys,so what I did today at the range(my buddys house) was I shot it and it wouldn't cycle; so I duplicated the problem. then,I swapped out my bolt carrier with his bolt carrier swapped out the gas blocks and put the lightest buffer I could find in the gun and it still wouldn't cycle so then I drilled the gas port out to .0938 and it would start cycling on maximum gas pressure but would short stroke on any gas pressure less than that. so what I did was a drilled it out to .1094. then put a spikes T2 buffer in it and dialed the adjustable gas block down about 1 1/2 maybe two turns and it started cycling perfectly. I figure this setting is perfect because he can still dial it down for higher pressure ammo or open it up for lower pressure ammo or maybe a different buffer or suppressor eventually one day. I ended up firing over 100 rounds of my handloads through it which are lighter than 556 ammo and it ran flawlessly no hangups at all.

honestly, I probably could have gotten away with a smaller gas port hole to drill but I figured hey go big or go home ...



lol no but really a 3/32 and 7/64 cobalt drill bit was easier to find than the ones in between.


thank you for all the help and ideas. I really appreciate this community. I hope my findings can help somebody figure out an issue with their gun someday.

 

[Medic!]

Its like vujida.

You know. The feeling that you've never done this before?

 

[freddyboomboom]

with a rifle length gas system and carbine buffer tube with a carbine weight buffer installed currently.

Rifle length gas systems need rifle buffers, which then require rifle buffer tubes and rifle buffer springs.

The springs are lighter weight, as well as the buffer being lighter weight due to lower gas pressure from the longer gas system.

For future reference.

 

[Iceman04503]

I've run rifle length gas system with an adjustable gas block on my ar with a carbine buffer, buffer spring, and t1 buffer without any problems.

 

[Member 5605]

I'm sure you verified alignment of the gas port and the hole in the gas block. Accounted for the distance of the metal ring that typically goes there and placed block in the right spot....