Short cycle issue

AR-15 » Troubleshooting

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Posted: 2/12/2017 2:04:07 PM EDT

Just finished 2 new builds last night. Went out to fire them today and both short cycled. Had numerous FTE and ftf and no last round hold open on magazine. Tried numerous mags that are known good on other builds. Started swapping uppers and lowers from other guns to eliminate possible issues. Took both current builds and finally installed my aim nib bolt carrier and both guns cycled fine, even had last round hold open. 1 rifle had case ejection at 2 the other at 4. The new builds used aim v2 nitride c 158 bcg and short cycle, but run fine with aim nib bcg. Anything I can do to these new bolts to tune them or check.

Posted: 2/12/2017 7:33:05 PM EDT

[#1]

How does each BCG feel when you have it out of the rifle to manually manipulate the bolt. Does it seem super stiff? Does it hang up in any areas?

Did you break down and clean each of the new BCGs? I'd do that and pull the extractors as well. Make sure nothing looks out of the ordinary. For the ejector, you can manually cycle it to ensure it is functioning properly. Test the feel against the known functioning BCG.

That'd be a good place to start. I'd also work on one rifle at a time in troubleshooting. Just because both are malfunctioning doesn't guarantee the root cause of the issue is the same.

When swapping parts, did you try these suspect BCGs in other rifles? Did you try putting either of the new bolts in the carrier that's a known quantity?

I think before anyone can provide better advice you have to focus on one BCG/rifle, and provide more details on what you've tried to troubleshoot. A few too many unknowns exist at the moment.

Posted: 2/12/2017 10:29:30 PM EDT

[#2]

Yep, a B/C is both the bolt and carrier. Hence you are confusing everyone if you are calling the pair just the bolt instead.

Since you have a working B/C, remove the bolt from it, install it on the working carrier, and the old working bolt on the new carrier.

Now with this combo with a few live fires, should be able to tell if its the new bolt that is causing the problem (not head spacing correctly, or too tight in the carrier), or the new carrier the problem (with either the key leaking against the top of the carrier, the bolt too tight in it, the key not aligning correctly with the gas tube, or just the carrier binding in the upper receiver.

As for a binding test, just shotgun the upper open ,install the B/C, shove your finger in the back of it, and work the B/C all the way back and forward in the upper. To check for key to gas tube alignment, pull the bolt off the carrier and install just the carrier in the upper receiver. When the front of the carrier is about 1" off face of the barrel extension, the gas tube is just entering the key.

If it turns out that its the new carrier the problem (their bolts run fine in the old carrier), and the carriers are not binding in the upper receiver/ gas tube aligned correctly to the key, then suspect that is the keys that are leaking against the top of the carrier. I could walk you through pulling the keys, lapping the two surfaces together, and installing the keys back on with new carrier with new bolts (including peening the key metal back into the side spines of the new bolt heads), but since you bought the B/C's new, send them back to let the manufacturer deal with the problem isntead.

Posted: 2/13/2017 6:58:08 PM EDT

[#3]

thank you for the ideas to check. think I narrowed it down to the carriers. the carrriers move free without binding i so disassembled 1 new bcg at a time, installed bolt into good carrier and function was fine in both instances. known good bolt installed into each new carrier produced same short cycle issue. I would have to assume its leaking. going to contact aim to see what they can do before I attempt to fix these.

Posted: 2/14/2017 12:45:08 AM EDT

[#4]

I'd say you've likely found the issue. If it is a leak, I wonder if they've got a whole batch out there like that. While it could be purely a coincidence that two bad ones make their way to one customer, the odds have to be pretty astronomical. Hope they get you squared away, and let us know how it turns out.

Posted: 2/16/2017 8:02:59 PM EDT

[#5]

The gas keys are not sitting flush, they are canted. Forgive me for being a newbie on these bcg, but is the seating area recessed with a defined edge the keys should sit in?. It appears on one the key is on a lip on the right, the other carrier key in up on the left. Used a straw and enough air comes out under the keys to blow out a match. Have pics, just have to figure out how to post them

Posted: 2/16/2017 8:10:32 PM EDT

[#6]

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Posted: 2/16/2017 10:52:11 PM EDT

[#7]

Looking at the canted gas key pic, I would contact the manufacturer and have the bolt carrier replaced. The gas key should be sitting flush and level, no cant.

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123

Posted: 2/20/2017 2:58:59 PM EDT

[#8]

Update, talked with customer service. I'm sending these back on my dime

. Asking for exchange, so we will see what they do. Will update on final outcome

Posted: 2/20/2017 11:32:56 PM EDT

[#9]

Well, I guess the good news is you may get some functional replacements. However, poor service on their part. Not all that smart either.

Sell 2 defective carriers + Make the customer dump money into fixing their problem + A market that's oversaturated with ARs and parts = A great first step towards going belly up.

The panic is gone. Long gone. The companies that will survive either need innovation, high quality output, competitive pricing, or great CS; preferably all 4.

Sorry to hear that OP. Hopefully the replacements work.

Posted: 2/21/2017 9:53:13 AM EDT

[#10]

Quote History

Quoted:
Update, talked with customer service. I'm sending these back on my dime

. Asking for exchange, so we will see what they do. Will update on final outcome

View Quote

I guess I missed it.

Who is this that sold you this crap so I can avoid them?

Posted: 3/2/2017 9:04:45 PM EDT

[#11]

Aim surplus is where I got this junk from. Still waiting on final outcome. Earlier this week they replied to my email after I inquired about status of exchange. There response was we may get to it this week. WTF, I'm done with them. These were 2 v2 nitride units that were junk from the assembly process. The gas key installation was a major fail. 99$ each + the 12$ shipping to send them there junk back. Now being held hostage awaiting new/ replacements hoping that they will be good. Seems like there is no desire or sense of urgency to make things right.
I ended up ordering 2 new toolcraft units from a vendor and have received them. They run flawlessly.

Posted: 3/4/2017 12:16:46 AM EDT

[#12]

this is why i stick to name brand shit.

aint no body got time for that

Posted: 3/14/2017 5:49:28 AM EDT

[#13]

Update,. I now have functional bcg's. They were out of stock on v2's, so I accepted a couple of there NB carriers. I have a couple of these already and never an issue with them. Still out $$ for shipping there junk back to them, was hoping for discount voucher on next purchase, but there was nothing in box other than parts. Didn't even get a "sorry for any inconveniences". Needless to say that was my last transaction with them!

Posted: 3/17/2017 11:44:14 PM EDT

[#14]

Well. Glad to hear they at least function now. That is crazy how they basically treated the problem like it was an inconvenience to them. Definitely not a market where companies can survive by pissing away customers.

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