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xnv733x
12-14-2008, 5:15 PM
i recently finished my first ar 15 build after i pull the charging handle with a chambered round i pull the trigger once the round is fired and extracted smoothly i am then left with the bolt completely forward with an empty chamber and hammer cocked back i dry fir it and have to pull the charging handle to chamber another round also upon testing the mag lock out it doesnt seem to lock the mag consistantly (sometimes after pulling the handle with an empty mag it does not lock out ) could this be anything besides a defective mag by the way its made by sabre defense thanks in advance for any help

MILLITIAof1
12-14-2008, 5:21 PM
sounds like the bolt is not moving far enough back to strip another round from the magazine(short stroking)

MILLITIAof1
12-14-2008, 5:23 PM
there are numerous causes of short stroking
underpowered ammo
carbon build up
not enough lube on the bcg
the list goes on and on, time to troubleshoot your rifle

xnv733x
12-14-2008, 5:30 PM
i was using remington 55g fmjs out of 60 rnds it did this about 90% of the timethere were two ocasions where it fired about 5 in a row before i had to pull the handle again and it was just cleaned and lubed today could it be short stroking even though it was extracting smoothly

xnv733x
12-14-2008, 6:45 PM
considering that the bolt travels far enough rearward to extract the empty cartridge can i rule out short stroking

The Cable Guy
12-14-2008, 7:07 PM
considering that the bolt travels far enough rearward to extract the empty cartridge can i rule out short stroking

No, the empty casing can still eject if the BCG isn't all the way back.

Jicko
12-14-2008, 7:16 PM
Is that a BRAND NEW upper? If so, please give it a thorough cleaning! And the lube the BCG, and make sure the gas rings on the bolt is not-aligned to each other.

With the upper off, make sure that your magazine is "activating" the bolt-catch when it is empty. Also, make sure that your bolt-catch is moving freely, put some CLP around the bolt-catch slot.

Lastly, when everything is cleaned and is well lubed, do this 100-200 times before your next range trip.
- with an empty magazine, pull your charging handle back until the bolt is locked back, and put the charging handle back
- release your bolt via the bolt catch
- dry fire
- repeat

Seesm
12-14-2008, 7:39 PM
Sell that pile to me "CHEAP" and build another... Yeah that's the ticket...

xnv733x
12-14-2008, 7:59 PM
it was used and i cleaned and lubed it today before taking it out is there any chance it is just the mag thanks for all the help

EOD3
12-14-2008, 8:41 PM
I have an Oly upper in 7.62x39 mated to a SunDevil lower that ejects the magazine if it's not seated FIRMLY. Next time it happens, give the magazine a good tug to make sure it's fully seated.

Dragon
12-14-2008, 8:50 PM
IF its used ,may be the gas rings need to be changed .

J_Rock
12-14-2008, 9:02 PM
Is that a BRAND NEW upper? If so, please give it a thorough cleaning! And the lube the BCG, and make sure the gas rings on the bolt is not-aligned to each other.



Even if the gas rings are aligned it wont cause any problems. The AR15 can run on 1 gas ring if needed. Its very long and perpetuated myth about the AR15

xnv733x
12-14-2008, 10:14 PM
i just completely disassembled the bcg after removing the bolt half of a broken ring fell out of the carrier i am planning on purchasing a new bolt any advice on which one to buy and from where

Jicko
12-14-2008, 10:24 PM
Even if the gas rings are aligned it wont cause any problems. The AR15 can run on 1 gas ring if needed. Its very long and perpetuated myth about the AR15

From what the OP found out, the hard way, obviously there are some merit to the myth....

With 1 of the rings failed, that's what it take to make OP's gun not work.

J_Rock
12-14-2008, 11:49 PM
From what the OP found out, the hard way, obviously there are some merit to the myth....

With 1 of the rings failed, that's what it take to make OP's gun not work.

From Pat Rogers:

"Replaces conventional three-piece “piston ring”-style sets that can accidentally line up, causing a major leak from the gas expansion chamber in the carrier."

That is absolute bull****.
It is no more than a myth that has turned into reality.

For many years the Colt Amorers course (when they used to do live fire) used a single bolt ring and the gun worked fine.

I have fired a buttload of rounds with a single bolt ring.

I learned to stagger the bolt rings in the Marine Corps because they were repating what the FM told them.

We know better now.

Bolt rings can wear, and should be replaced at interval. A one piece ring is no better/ worse than 3 single bolt rings.

The key here is to check them regularly and replace when necessary.

But staggering them? A big waste of time.


I can imagine that it was the broken piece that gummed up the works not the lack of a gas ring. I'm sure someone much more knowledgeable will come around and set the record straight. Obviously this would be very easy to test out for yourself

The Cable Guy
12-14-2008, 11:57 PM
From what the OP found out, the hard way, obviously there are some merit to the myth....

With 1 of the rings failed, that's what it take to make OP's gun not work.

Im still thinking its a short stroke due to the buffer.buffer spring.

aplinker
12-15-2008, 1:01 AM
i just completely disassembled the bcg after removing the bolt half of a broken ring fell out of the carrier i am planning on purchasing a new bolt any advice on which one to buy and from where

What broke? The gas ring, the bolt, the cam pin?

Bravo Company will have what you need, except bolts - no one has those right now.

To diagnose short stroking put 1 round in the magazine and, with the bolt locked back, put the mag in. Fire and see if the bolt locks back itself. If not, you're likely short stroking.

xnv733x
12-15-2008, 3:42 AM
Im still thinking its a short stroke due to the buffer.buffer spring.
how could this be possible and how can i check for this

aplinker
12-15-2008, 12:16 PM
how could this be possible and how can i check for this



To diagnose short stroking put 1 round in the magazine and, with the bolt locked back, put the mag in. Fire and see if the bolt locks back itself. If not, you're likely short stroking.

You'll want to make sure that the bolt locks back on the empty mag when cycling by hand, first.

Check your buffer and see if it's marked "H" or "H2", etc.

xnv733x
12-15-2008, 4:27 PM
what is the difference between the two

1BigPea
12-15-2008, 4:58 PM
what is the difference between the two

It's the weight of the buffer, the higher the number the higher the weight.

Car std 3.0oz
Car H 3.8oz
Car H2 4.6oz
Car H3 5.4oz

xnv733x
12-15-2008, 5:45 PM
how do i determine which one im supposed to use

xnv733x
12-15-2008, 5:59 PM
i just looked at it there are no markings on it it came with my vltor stock also could the broken gas ringhave caused any damage to the bolt or carier and is it a bad idea to shoot it with a missing ring

redcliff
12-15-2008, 6:22 PM
Visually inspect the bolt and bolt carrier for any gouging. The broken gas ring probably didn't hurt anything, although the question remains as to why it broke in the first place.

I personally would not shoot it with a broken ring, since likely the rifle will keep short stroking anyway till you fix it.

xnv733x
12-15-2008, 6:36 PM
i didnt see any gouging as to why it broke im guessing it was due to the fact that the previous owner never cleaned it it was very dirty even the firing pin was pretty grimy

ccmano
12-15-2008, 6:45 PM
I doubt the gas ring has anything the do with it... that said, make sure you replace all the rings, they're there for a reason.

I had the same issue a few years back with an Oly lower and an RRA National Match upper. On mine, the buffer system was the problem but in the way you might think. I changed springs and buffers with no improvement. I don't recall how but we determined that the screw that holds stock to the buffer tube needs to be vented. Early screws were solid and are still available. Late model screws are vented with a hole down the middle. The vent allows the air to escape as the buffer is pushed back into the tube as the bolt carrier recoils. The lack of a vent hole caused the air in the tube to act as a cushion causing short stroking. I changed the screw and the problem went away.

I'm not saying thats your problem, there are many reason for short stroking (so to speak) but is worth a look.
:cheers2:

Spyder
12-15-2008, 7:14 PM
Same problem with my SP-1 upper. Go check out that thread, posted earlier today for some more fixing advice. "SP-1 help, or something like that is the thread title.