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Author Topic: New AR is short stroking - Ejects but has Failure to Feed  (Read 2166 times)
joep19934
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« on: April 25, 2017, 05:22:12 AM »

Ok for all intense purposes the gun is acting like it has a low gas pressure issue - But!
I have been down to the range twice now and have found the Mil Spec buffer tube assembly I installed is causing my issue.
It's a Mil Spec carbine length buffer tube but the spring was too long and stopped the bolt ( 18" barrel length rifle gas system w/ .750 low profile gas block )  from going back enough to chamber another round and lock on last round. ( I have tried 2 brands of ammo as well same outcome didn't change anything ).
I tried 2 other lowers I had with carbine buffers and they both did the same thing.
I decided to cut the spring a little thank goodness I had some cutters with me. I first took off 3 coils.
It was better but still failed to load another round or stay opens on last round.
I took another 2-3 coils off and the bolt started to cycle and load the next round and stay open on last round.
Ok so that fixed it for the time being so now to figure out how to fix it permanently,
It is an 18" Wylde barrel with a rifle length gas system with a .750 gas port, everything is lined up correctly. ( Nothing is loose or misaligned I took my time doing this )
I have to double check the gas key tonight to make sure it is tight, even though its new it could still be loose from what I have found online. ( It is staked ) I highly doubt it is bad though.
I would really like to keep the 6-position stock on it with the carbine buffer tube but its looking like it may need a rifle length buffer tube and stock. ( don't know for sure getting a $60 Rifle length buffer kit will fix it 100% if it is under gassed )
Or do I take it all apart and drill out the gas port on the barrel a little bit to try and bring up the gas pressure more and be able to carbine buffer with the correct length spring....
From all the reading I have done online a rifle length upper should work with a carbine buffer tube is there any reason why it wouldn't?

hmmmm I don't know Sad   Roll Eyes
I know cutting the buffer spring isn't a fix but still looking for the cure and I know I will get it over time  Grin
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Federal Firearm
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« Reply #1 on: April 25, 2017, 08:43:44 AM »

check the gas-port in the barrel......if not follow it down make sure nothing (primer) or pieces got loose and trapped...if all else fails i can have gunsmith look at it...
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joep19934
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« Reply #2 on: April 25, 2017, 09:12:33 AM »

check the gas-port in the barrel......if not follow it down make sure nothing (primer) or pieces got loose and trapped...if all else fails i can have gunsmith look at it...
Thank you Chris, I can blow through from the BCG side of the gas tube and it doesn't appear to be blocked.
I was thinking about taking the handguard off tonight and checking it just to make sure, I did take my time when working on the gas system and with aligning everything.
For the life of me no matter what length upper you have the BCG should work with any Carbine length tube but mine wont until I chopped the buffer spring down.
I tried it on 2 other working lowers and the BCG wont go back far enough in those either.
I have looked online for the longest and found that some barrels over 18" need a rifle buffer tube but cant grasp what barrel length has to do with a BCG being able to slide back into a Carbine Buffer tube.

Am I missing something ?  Huh
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joep19934
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« Reply #3 on: April 25, 2017, 07:25:31 PM »

OK I disassembled the rifle again and everything looks good.
The gas system was clear and nothing was blocking to port in the barrel or the tube or gas block itself.
The alignment looked ok to me.
I tried the other lowers again and when pulling back the charging handle the BCG does go back into the buffer tube on all the other lowers I have.
It looks like another range trip will be coming up soon.
If it wont cycle I think I may drill the gas port on the barrel out a little larger maybe one or two drill bit sizes up.
Shoot it and see if that helps with cycling.
I just have to remember to bring the drill and some bits with me that day. LOL  Grin Roll Eyes
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joep19934
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« Reply #4 on: April 26, 2017, 08:10:01 PM »

Just an update,

I drilled out my gas block gas port to 1/8" and I have ordered a Rifle Buffer Kit assembly.
After the rifle buffer kit comes I will go test it again and if the rifle cycles ok great....
If not I will be drilling the Gas port on the barrel itself a little larger than the 3/32 it is currently.

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MarkB
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« Reply #5 on: May 25, 2017, 09:07:57 PM »

It sounds like you have a spring that is just too long.  There both a rifle length and a carbine length spring available for the AR15.  You may have a rifle length spring when you need a carbine length spring.  
« Last Edit: May 25, 2017, 09:11:11 PM by MarkB » Logged

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joep19934
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« Reply #6 on: May 26, 2017, 05:48:21 AM »

It sounds like you have a spring that is just too long.  There both a rifle length and a carbine length spring available for the AR15.  You may have a rifle length spring when you need a carbine length spring.  
Hi Mark,

The Buffer assembly is all Carbine length, spring and everything. ( I have triple checked everything )
I think I may have found the culprit.
I am pretty sure the gas block port itself was too small ( I have no idea why it was smaller then it should have been ), I have drilled it out but haven't had time to get out to the range and test it yet.
I haven't had time to go test the rifle yet but I did buy a UTG Rifle buffer kit to swap out if it still short cycles.
The 3rd and last thing I would try is bore the Gas port on the barrel, I have someone with all the proper stuff to do it correctly.
Everything I have found and read and also talked to other people about is an 18" barrel can be very particular and not matter what you do would require a Rifle Buffer assembly ( I have to realise that is what I may have to end up swapping out no matter what I try )



« Last Edit: May 26, 2017, 05:50:36 AM by joep19934 » Logged

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