Issue with JP Silent Captured Spring?

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Phoneguytim
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Joined: Fri Mar 13, 2015 5:58 pm

Issue with JP Silent Captured Spring?

Post by Phoneguytim »

Hello all. I recently put together a 300 blk sbr. I've taken it to the range a couple of times now and notice that every once in a while the carrier group does not go into battery.

The subsonic rounds I'm using cycle the rifle ok. And the bolt locks back fine when the last round is fired from the magazine. I'm wondering if the JP Silent Captured Spring I'm using isn't pushing the carrier group forward with enough force.

What do you guys think?
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themonk
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Re: Issue with JP Silent Captured Spring?

Post by themonk »

Possible. First, what ammo and what length barrel/gas system? Does this happen with supers?

When you installed the SCS did you look at #4 of the instructions:
#4) Reassemble the upper and lower assemblies with the front pivot pin and slowly lower the
upper into position. Watch carefully as the receivers are closed to verify that the SCS
buffer head contacts the bolt carrier. If you are not certain if there is a gap, finish
reassembling the rifle and then shake it back and forth gently listening for the sound of the
SCS sliding back and forth in the buffer tube. The unit should not be moving freely.

The precise length of the SCS was chosen to accommodate most rifles, but if you detect a
gap between the bolt carrier and SCS, this is due to slight variations in the manufacturing
tolerances of the buffer tube, bolt carrier and receivers. To shim this gap, the best solution
we’ve found is to simply place a quarter in the buffer tube before installing the SCS. It will
not be necessary to use more than one, and you should not use extra shimming to
“preload” the SCS. We offer alternate rate springs for this purpose.


Its possible that if there is a gap this may be causing it.
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farm use
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Re: Issue with JP Silent Captured Spring?

Post by farm use »

I agree you probably have a gap between the carrier and spring. I got 2 of these yesterday and found one of my buffer tubes is 3\16" deeper than others. So I have a small gap.
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r.tenorio671
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Re: Issue with JP Silent Captured Spring?

Post by r.tenorio671 »

...based on it occurring sporadically, it may also be ammo related if you were using handloads due to the cases not being properly resized at the web (recommend full length, small based sizing).
Phoneguytim
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Joined: Fri Mar 13, 2015 5:58 pm

Re: Issue with JP Silent Captured Spring?

Post by Phoneguytim »

Thank you, I will take a look and see if there is a gap. I'll post back when I find out.
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farm use
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Re: Issue with JP Silent Captured Spring?

Post by farm use »

My gap was 3/16", I used a 1 inch rubber stopper from Lowes, cut it down to about 3\16" then sanded it on down to where it needed to be. Then shaved some off the edges to get it just under an inch. Put down in the buffer tube behind the SCS, works like a charm!!
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