Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
User Panel

Site Notices
Posted: 4/19/2011 4:28:56 PM EDT
I put together an ar, the upper half had been used, the lower all brand new. I lubed everything up really well, but when i took it to the range, i was having problems with FTE on the first round.  The rest of the magazine worked alright after that. After leaving i came to the conclusion that it probably wasnt going fully into battery when the charging handle was used. This doesnt happen on brass cased ammo, only the first of 20 steel rounds in a 30 round mag. I have tried 3 different mags. I am not riding the charging handle forward.

Link Posted: 4/19/2011 4:34:57 PM EDT
failure to extract is not the same as a double feed.  Double feeds are strictly a magzine issue. Pull the ch all the way back and let go, its not hard. You don't need lube in the buffer tube.
Link Posted: 4/19/2011 4:35:31 PM EDT
Link Posted: 4/19/2011 4:43:05 PM EDT
Your buffer should not be lubed, and your buffer spring should only have a VERY light layer of oil, to help prevent rust. What upper were you using, and what kind of ammo? Try a different brand of ammo, preferably of high quality. Sometimes the cheaper steel ammo doesn't have enough umph to cycle the action completely. Also, what buffer weight are you using?
Link Posted: 4/19/2011 6:03:54 PM EDT
So the upper is used ?

Sounds like the bolt could be  slamming into battery better on the second shot and the (used) extractor gets a better bite.
I also think that your bolt/extractor needs a look see. Inspect for wear.

It's always good to use a bolt that is HP/MPI tested and built to spec.
You might want to replace the bolt with a new one :
https://www.cobratactical.com/LMT-L7A3B-Standard-Bolt-Assembly-556mm_p_7058.html

You could also put a rebuild kit in your old bolt for about $25 - $30

Lastly, you could just install a new extractor spring kit. The spring in this kit is strong and you typically do not need the o-ring with it.
https://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm

Link Posted: 4/19/2011 7:50:53 PM EDT
No, i am not riding the handle.

I will inspect the extractor, and maybe replace it.  What does a worn extractor look like?  The bolt and carrier are bcm and i believe the bolt says mpi on it, so it should be high quality, but are used so may be worn.  The seller said he only shot about 500 rounds from it though.  I only have this problem on the first shot, so i think the ammo has enough power, though it was cheap steel tul ammo.  I am using a h buffer and mid length gas system.  I have no problems with all other rounds, just the first one that i manually chambered.  I know ar's are picky about steel ammo, and maybe thats the cause.  If thats the case, ill make sure and use the forward assist on the first round when using that ammo.  I dont want to jump to the conclusion that it is the ammo though and would like to hear other possibilities.
Link Posted: 4/19/2011 8:01:59 PM EDT
Start by getting some new mags..double feeds are mag related and thats what could be giving the carrier problems cycling as well.Replace the mags ge tsome new ones and then see.
Link Posted: 4/19/2011 8:14:28 PM EDT
I think the problem is more of an extraction problem. It isnt extracting the spent casing, and jamming the next round in with it. I should be calling it an extraction problem rather than a double feed.  

I have tried 3 magazines, one of which was a brand new never used pmag
Link Posted: 4/19/2011 8:19:40 PM EDT
They are not.   As long as your rifle isn't a piece of shit, it will work just fine with steel cased ammo.

Quoted:
I know ar's are picky about steel ammo,


When troubleshooting, start with the lowest common denominator; in this case, the extractor.  Get a new extractor with a black insert and a quality spring.
Link Posted: 4/19/2011 8:24:53 PM EDT
Quoted:
No, i am not riding the handle.

I will inspect the extractor, and maybe replace it.  What does a worn extractor look like?  The bolt and carrier are bcm and i believe the bolt says mpi on it, so it should be high quality, but are used so may be worn.  The seller said he only shot about 500 rounds from it though.  I only have this problem on the first shot, so i think the ammo has enough power, though it was cheap steel tul ammo.  I am using a h buffer and mid length gas system.  I have no problems with all other rounds, just the first one that i manually chambered.  I know ar's are picky about steel ammo, and maybe thats the cause.  If thats the case, ill make sure and use the forward assist on the first round when using that ammo.  I dont want to jump to the conclusion that it is the ammo though and would like to hear other possibilities.

That's a very good bolt and still young with only 500 rounds through it.

This FTE, does the spent case stay in the chamber ?
Link Posted: 4/19/2011 8:34:19 PM EDT



Quoted:


They are not.   As long as your rifle isn't a piece of shit, it will work just fine with steel cased ammo.




Quoted:

I know ar's are picky about steel ammo,




When troubleshooting, start with the lowest common denominator; in this case, the extractor.  Get a new extractor with a black insert and a quality spring.


There are plenty of "Tier 1" rifles that won't cycle Wolf, at least initially



 
Link Posted: 4/19/2011 8:36:28 PM EDT
Quoted:
They are not.   As long as your rifle isn't a piece of shit, it will work just fine with steel cased ammo.

Quoted:
I know ar's are picky about steel ammo,


When troubleshooting, start with the lowest common denominator; in this case, the extractor.  Get a new extractor with a black insert and a quality spring.


Woah dude, some rifles ARE picky about steel case, it has NOTHING to do with 'being a piece of shit'. For instance, LMT is specifically made with a smaller diameter gas hole drilled so that it functions with high powered ammo. My LMT SBR will NOT function reliably with Tula ammo, however will run wolf okay, and anything brass does fine.

As for the OP. Before you spend all kind of money on different parts, try a different ammo. Tula is the lowest powered ammo out there, buy a single box of brass cased ammo, or even try Wolf, and see if you have the problem. Because you are using a low powered ammo, AND running an H buffer, I do not think your bolt carrier is traveling all the way to the rear, henceforth why the round will not extract. However, it travels just far enough for the second round to move up, and jam.

To reiterate; spend 10 dollars on a walmart box of .223, it doesn't have to be federal 855 or 193, but anything that is brass and packs more of a punch than Tula. I believe this will fix your problems, if it does, great! you just saved yourself money  for buying extra parts (which you should buy later anyway) but you also diagnosed your problem.
Link Posted: 4/19/2011 9:30:56 PM EDT
The spent casing doesnt stick in the chamber, i can pull it out with my fingers. I think its an extractor problem.  

I dont see what higher pressure ammo has anything to do with it. It cycles fine.  Its the bolt closing on the first round that im having a problem with.

If you guys are saying try different ammo because tula might be out of spec i understand that.  I can not recall correctly, but i think it did the same thing with brass pmc
Link Posted: 4/19/2011 10:06:02 PM EDT
i dont know if this can be done but could it be the bolt is turned the other way and the extractor is on the opposite side ? like i said i dont if if this is can be done but it always runs through my head when im assembling my gun.
Link Posted: 4/19/2011 10:31:56 PM EDT
Quoted:
The spent casing doesnt stick in the chamber, i can pull it out with my fingers. I think its an extractor problem.  

OK, so the spent case remains fully in the chamber but not stuck ?
If so then yes, the extractor is simply not gripping the case lip.

I would take the bolt out of the carrier and then disassemble the extractor.
If there's an o-ring present take it off.
Look over extractor, spring and insert. Hopefully everything looks like the extractor with the longer spring in the pics.
Reassemble and check for good spring action.

Here are some pics. You may be able to use your browser to zoom on them to see more detail : (enough res for 200%)
AR Bolt Teardown
Link Posted: 4/20/2011 6:41:13 PM EDT
The spring looks like the smaller one with the blue thing. No o-ring. It only happens with the steel ammo, not brass. The extractor itself looks like its in good shape. Hitting the forward assist didnt make a difference.

Do you think a wolff extractor spring would help?
Link Posted: 4/20/2011 8:20:27 PM EDT

Do you think a wolff extractor spring would help?

Couldn't hurt or get a BCM kit which has the bigger spring and a black insert.
http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm


I'm wondering if the bolt is BCM with the small spring and blue insert.
Maybe back in the day that's how BCM shipped bolts.

It would be interesting to see if a different bolt assembly would work.

Link Posted: 4/21/2011 12:31:54 AM EDT
I'm confused. Are you firing the first round and having the empty case stay in the chamber, or are you having the bolt not go fully into battery when you charge it?
Link Posted: 4/21/2011 3:48:03 PM EDT
Quoted:
I'm confused. Are you firing the first round and having the empty case stay in the chamber, or are you having the bolt not go fully into battery when you charge it?


The first empty case is staying in the chamber.  I thought it might not be going fully into battery, but i was wrong.

I talked to bcm and they said it might not be theirs, even though the seller said it was. It could be a much older model though.  I guess i would be pretty frustrated if i find out its not bcm like i was told, but then again, if the spring fixes it i have no other complaints with the upper half.
Link Posted: 4/21/2011 4:08:16 PM EDT
Buy a chamber brush and clean the chamber out real well (If you don't own one... slap yourself)

Buy a new extractor with a good spring (I like BCM)

install and lube and go shoot..

problem solved....

cost less about $10.


Why??

cause you bought a used upper and really have no clue what is up with it.... seller says 500rds... could be 5000 for all you know..

Steel case does  have a tendency to stick in a chamber and a weak extractor spring with a worn extractor can slip off the case rim during initial extraction of the fired casing, causing the problem your describe. plus you'll know what the condition of your extractor and spring now is..... it's new...
Link Posted: 4/21/2011 4:49:20 PM EDT
Quoted:
Quoted:
I'm confused. Are you firing the first round and having the empty case stay in the chamber, or are you having the bolt not go fully into battery when you charge it?


The first empty case is staying in the chamber.  I thought it might not be going fully into battery, but i was wrong.

I talked to bcm and they said it might not be theirs, even though the seller said it was. It could be a much older model though.  I guess i would be pretty frustrated if i find out its not bcm like i was told, but then again, if the spring fixes it i have no other complaints with the upper half.


A BCM carrier is very easy to identify and the bolt will have a laser etched MP or a "combined" MP.






Combined MP :





Link Posted: 4/29/2011 10:33:13 PM EDT
wolff hd extractor spring seems to have cured my problem. I went through 5 boxes of steel tul ammo today without a single problem
Link Posted: 4/30/2011 4:57:48 AM EDT
You can thank me later......

And good job on following up on this thread... good info can help others......
Link Posted: 4/30/2011 4:53:14 PM EDT
Quoted:
wolff hd extractor spring seems to have cured my problem. I went through 5 boxes of steel tul ammo today without a single problem

Good news !

PS
Don't thank that douchebag

An error occurred on the server when processing the URL. Please contact the system administrator.

If you are the system administrator please click here to find out more about this error.