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nCarnage
21 October 2015, 13:25
So I decided to go shooting today. Noticed that my bolt won't lock back on the last shots which pissed me off because I spend good money.
I tried different magazines (gen 2 and 3 pmags). Ammo was federal 55gr 5.56 fmj.
Was thinking either it's the ammo, the buffer spring is to strong, buffer to heavy or something wrong with the bolt catch.

It catches when I put an empty mag and rack it manually.


Specs:
Spikes tactical gen 2 billet lower
Damage industries enhanced carbine buffer spring
Spikes tactical t2 buffer

Upper:
Long dog tactical bcg
Daniel defense 14.5" mid length pinned spikes tactical barking spider 2 pin/weld


What do you guys think?


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Dstrbdmedic167
21 October 2015, 13:28
Try a standard carbine buffer and spring. That would be my first attempt to fix the problem.

Never heard of the BCG but I assume a standard phosphate milspec BCG?

What gas block are you running?

nCarnage
21 October 2015, 13:30
Try a standard carbine buffer and spring. That would be my first attempt to fix the problem.

Never heard of the BCG but I assume a standard phosphate milspec BCG?

What gas block are you running?

Daniel defense from factory, pinned. BCG I won it from stickman last Halloween. :) it's nickel boron.

Oh and oil used is frog lube. Which I hope isn't making the bolt catch stick.


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Dstrbdmedic167
21 October 2015, 13:34
Daniel defense from factory, pinned. BCG I won it from stickman last Halloween. :) it's nickel boron.

Oh and oil used is frog lube. Which I hope isn't making the bolt catch stick.


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Missed that my bad... Good win! I don't think froglube is you're issue. In fact the video's just posted are using a new ucwrg BCG that I slapped some froglube on before I hit the range.

nCarnage
21 October 2015, 13:41
All righty. I shall try swapping the buffer on my next outing with the other rifle. See if that's the problem before I start ordering parts


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Dstrbdmedic167
21 October 2015, 14:00
Also try different ammo before you change anything and then use the federal with a spring change if the problem persists..

nCarnage
21 October 2015, 14:07
Also recall swapping uppers and it did the same thing


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UWone77
21 October 2015, 14:14
BCG is where I'd start.

toolboxluis00200
21 October 2015, 14:16
Did u cheak your bolt catch to see if it to tight

nCarnage
21 October 2015, 14:22
Did u cheak your bolt catch to see if it to tight

Would release easily on both ambi controls. Bcg was thinking about buying one anyway. Think I have a spare buffer spring somewhere.
Appreciate all the input


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toolboxluis00200
21 October 2015, 15:12
Hope u get it fix

nCarnage
21 October 2015, 16:06
Hope u get it fix

Yeah. I hope so too. Need to fix it before May 2016 which is plenty of time. Just my gun fund will become a no-Gun fund.


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Dstrbdmedic167
21 October 2015, 16:48
Yeah. I hope so too. Need to fix it before May 2016 which is plenty of time. Just my gun fund will become a no-Gun fund.


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You must have a little one on the way... If so congrats!

RiverRat
21 October 2015, 17:05
Also recall swapping uppers and it did the same thing

Double check this.....if the bolt won't lock back with either upper, it's in your lower. If you have another bullt up lower, you can verify that your new upper functions on that old lower as verification.

And you said the bolt will catch if you rack with an empty mag and release properly with all controls, so I don't suspect a problem with the catch. I would check the buffer and edges/inside of the extension to see if there is obvious evidence of friction (just barely short stroking) and check for magazine wobble in the well that might prevent latching under firing conditions. I've had enough strange malfunctions with billet lowers that I wouldn't be terribly surprised if it were a mag fit/tolerance issue. Failing to find a problem with that, I would swap the spring first, then the buffer (using the older upper that you know works first) to see if you can isolate a problem point.

Ulitimately, all this troubleshooting is done most easily if you can isolate increasingly smaller groupings of components as the issue. Good luck.

nCarnage
21 October 2015, 17:16
Double check this.....if the bolt won't lock back with either upper, it's in your lower. If you have another bullt up lower, you can verify that your new upper functions on that old lower as verification.

And you said the bolt will catch if you rack with an empty mag and release properly with all controls, so I don't suspect a problem with the catch. I would check the buffer and edges/inside of the extension to see if there is obvious evidence of friction (just barely short stroking) and check for magazine wobble in the well that might prevent latching under firing conditions. I've had enough strange malfunctions with billet lowers that I wouldn't be terribly surprised if it were a mag fit/tolerance issue. Failing to find a problem with that, I would swap the spring first, then the buffer (using the older upper that you know works first) to see if you can isolate a problem point.

Ulitimately, all this troubleshooting is done most easily if you can isolate increasingly smaller groupings of components as the issue. Good luck.

Thanks. Will do that.


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nCarnage
21 October 2015, 17:57
You must have a little one on the way... If so congrats!

😉😉

Edit: would be #1.


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Jerry R
22 October 2015, 09:00
I tend to agree with folks above that recommend changing the buffer. Spike's site says the ST-T2 will vary between 4.0 and 4.2 ounces. Other carbine buffer weights are:

Standard = 3.0
H = 3.8
H2 = 4.6

and they go up from there.

Buffers are relatively cheap on the lower weight end of the spectrum. You might try the H buffer, which would at a minimum cut two tenths off, and maximum four tenths. If your system is close, shaving that small an amount might fix it and still not be hard on the parts. Again, "assuming" the buffer is the problem.

Having said that, I had a similar issue when I tried a Wolff XP Carbine spring in combination with an H2 buffer. Put a standard spring back in, kept the H2, and the lock-back problem went away. I am not familiar with Damage Industries Enhanced buffer spring. If it offers increased resistance - it may be the problem.

Change one thing at a time.

SINNER
22 October 2015, 09:37
Put a Standard carbine buffer in it and be done. The dwell time on the 14.5" middy DD barrel is very short. Mine runs like a champ with a carbine buffer and a white Springco spring in it. Had issues with FTF's with full mags with mine.

nCarnage
22 October 2015, 12:23
Ok this is what I'm seeing.
1) noticed i put a standard carbine buffer spring in instead of the enhanced. So it does have a standard carbine buffer spring

2) went a little nuts with the frog lube and was everywhere. Making it almost sticky. That is now cleaned.

Now this is what I'm noticing.
With an empty 30 round pmag, both gen 2 and 3, it will trigger the bolt catch just slightly where the bolt will not catch it but just skim passed it. This then created a groove in the bolt catch.

Now I notice if I rack the 30 rounders really good, it will catch all the time. Same with the 20 rounders.

Tried whatever magazines I found in the house. Did the same thing. http://images.tapatalk-cdn.com/15/10/22/2518df12340453f5053e5164db005067.jpghttp://images.tapatalk-cdn.com/15/10/22/2f4c2eecbba20ab2062b308eb701c5f8.jpg
http://images.tapatalk-cdn.com/15/10/22/5de8a6064bc6928fd6930b9687ec1853.jpg


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Edit: tried the spikes upper with a seekins lower. Does the same thing.

nCarnage
23 October 2015, 16:39
Talked to their customer service which I think are great people. Going to send me a bolt catch assembly with all springs. Hopefully that works. They are thinking it is either the bolt catch is a tad to big where the plunger makes contact or the cross pin for the ambi-switch bolt catch release maybe to long. We shall see. Right now trying to figure out how to remove a strip retention screw. Never learned when to quit when things are going bad and just need to step away.


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nCarnage
5 November 2015, 09:31
The parts finally came in and I assembled the lower after a good cleaning. At the moment, racking the bolt with an empty mag, the bolt locks back. Which made me happy. The ultimate test is to take it to the range and fire a good amount of rounds.