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Which Recoil System? JP SCS Gen 2 vs MBX PCC Buffer System


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3 minutes ago, 1911luvr said:


Ah, I see you've had to do it too!


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That was because my snap ring came off and the buffer weights/orings became loose in the buffer tube. I've never had them get shredded under normal use. But I have seen others. I think it happens if you don't oil the weight carrier.

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That was because my snap ring came off and the buffer weights/orings became loose in the buffer tube. I've never had them get shredded under normal use. But I have seen others. I think it happens if you don't oil the weight carrier.

Interesting. I had been using a little Hornady One Shot on it but since JP's instruction say not to oil the buffer I had been using it sparingly. Maybe I should be using more. Despite using light oil I still had lots of powder residue in the tube, which I was guessing was from running my Bullseye loads.


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10 minutes ago, 1911luvr said:


Interesting. I had been using a little Hornady One Shot on it but since JP's instruction say not to oil the buffer I had been using it sparingly. Maybe I should be using more. Despite using light oil I still had lots of powder residue in the tube, which I was guessing was from running my Bullseye loads.


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IDK i never read instructions lol

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IDK i never read instructions lol

Apparently I shouldn't have either! I've learned more from breaking things than I probably ever could have without. Expensive lessons sometimes though, but certainly well learned!


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2 hours ago, Maxamundo said:

If any of you guys have the 9mm JP SCS, you'll want the CS100-M11 to do pretty much the same thing. It did improve the SCS for me a lot. You put it under the plastic bumper at the bottom of the SCS. 

 

You're talking about sandwiching it inbetween the white delrin bumper and the thin black end cap? I put an order in for one. So with that, I need to order a JP AR15 85% Black Spring and add an additional tungsten weight?

Edited by KzBoost
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7 hours ago, Aircooled6racer said:

Hello: Is it me or is there some bump firing going on in those videos? Thanks, Eric

I've experience it a couple times with a JP trigger group that's setup with fairly short reset. Not totally sure, but it seems the way these 9mm carbines recoil it could be contusive to bump firing if the operator is hanging on the trigger a bit (pardon my poor descriptive nomenclature). 

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13 hours ago, KzBoost said:

 

You're talking about sandwiching it inbetween the white delrin bumper and the thin black end cap? I put an order in for one. So with that, I need to order a JP AR15 85% Black Spring and add an additional tungsten weight?

 

Yes. If you call JP they will sell you individual springs for $8 each instead of having to buy the whole pack for $40.

The extra tungsten weight is optional but I found I liked it maxed out with tungsten. The theory is short travel leads to fastest dot recovery and trigger reset. But also hits your shoulder harder so it lessens the benefits. To counteract that we add the 2nd spring (instead of just solid spacer) to increase cushioning and extra weight to slow down the cycle speed and smooth it out. The mainspring we switch to a lighter one because dot recovery depends as much a softer return to battery as it does on a softer bottom out. Because of the extra spring taking up space, you'll get some pre-compression of the mainspring so the 85% might perform like a 95% and so on.

 

Everyone's gun and ammo and shooting stance is different, so I can't give you the answer to what's best for you. Unfortunately there is no single answer and everyone should do a little experimenting. 

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9 hours ago, Aircooled6racer said:

Hello: Is it me or is there some bump firing going on in those videos? Thanks, Eric



Absolutely, I view it as more of a "controlled bumpfire". I can actually pretty consistently hit only 2 shots. It's like double clicking a mouse. In your head it's one action, but you don't accidentally "triple click" the mouse.

I'm definitely not 100% consistent with it. I still get trigger freeze sometimes and will accidentally bump 3 instead of 2 other times. But it's a skill I'm working on that's unique to my specific PCC. Again I've never been able to do this with my .223 rifle. The recoil impulse is drastically different.

For example check this video since it has a good variety of controlled bumpfire, controlled double taps, trigger freeze, etc: 

I'll go in order of targets engaged and explain what each was.

Target 1: Controlled bumpfire (2 shots)

Target 2: Popper, single shot

Target 3: controlled bumpfire (2 shots)
Target 4: medium range no-shoot, 2 sight pictures, 2 shots
Target 5&6: Traditional double tap, one sight picture, 2 conscious trigger presses, not bumpfire

Target 7: Popper, single shot (one miss)

Target 8&9: double tap, one sight picture, 2 conscious trigger presses, not bumpfire

Target 10: popper, single shot

Target 11: controlled bumpfire (2 shots)

Target 12: attempted controlled bumpfire, with triggerfreeze

Target 13-17: normal double taps, not bumpfire

Target 18: medium range no-shoot, 2 sight pictures

Target 19: 3 sight pictures, called one miss so one make-up shot

Target 20: medium range no shoot, 2 sight pictures

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Also this is a relatively new skill for me, it kind of just started happening subconsciously as I was shooting the Safariland match. When I shot the splits in this video and that other one with the spinner and the step-plate, I was like wow, I've never ever shot splits that fast in a match before. 

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Little off topic, but was just finishing up loading for match tomorrow (9mm PPC) and the carbide seizer ring pulled out of the sizing die. Dillon of course has replacement die on the way. Luckily had enough ammo loaded. Never know what will happen next...

 

 

case.JPG

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3 hours ago, Maxamundo said:

 

Yes. If you call JP they will sell you individual springs for $8 each instead of having to buy the whole pack for $40.

The extra tungsten weight is optional but I found I liked it maxed out with tungsten. The theory is short travel leads to fastest dot recovery and trigger reset. But also hits your shoulder harder so it lessens the benefits. To counteract that we add the 2nd spring (instead of just solid spacer) to increase cushioning and extra weight to slow down the cycle speed and smooth it out. The mainspring we switch to a lighter one because dot recovery depends as much a softer return to battery as it does on a softer bottom out. Because of the extra spring taking up space, you'll get some pre-compression of the mainspring so the 85% might perform like a 95% and so on.

 

Everyone's gun and ammo and shooting stance is different, so I can't give you the answer to what's best for you. Unfortunately there is no single answer and everyone should do a little experimenting. 

Thanks for the input! Much appreciated. 

 

Would you mind sharing what kind of ammo you were using with the JP SCS tuned that way? 

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18 minutes ago, KzBoost said:

Thanks for the input! Much appreciated. 

 

Would you mind sharing what kind of ammo you were using with the JP SCS tuned that way? 

 

130pf 147 or 135gr coated bullets with prima V powder.

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4 hours ago, Maxamundo said:

Also this is a relatively new skill for me, it kind of just started happening subconsciously as I was shooting the Safariland match. When I shot the splits in this video and that other one with the spinner and the step-plate, I was like wow, I've never ever shot splits that fast in a match before. 

 

A while back I was getting doubling and tripling.  Some speculated it was bump-firing.  In my case it was not controlled bump firing.

 

That brings me to my question.  To be able to bump fire on command, does your gun need to be set up on the ragged edge?  Does it ever bump fire when a traditional double tap was desired?

 

Good news, I now know what combination of springs and buffers will let me bump fire like the pros.  I'm just not sure I want to.  ;)

Edited by Flatland Shooter
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So Max.

 I run factory WWB 115 gr ammo. JP GMR-13 upper. I would am planning on ordering the Blitzkrieg buffer. What spring would you recommend for it? 

 

 I just want it to run and do not want to do a bunch of experimenting. 

 

Also, I am intrigued by the wave spring behind the buffer spring cap. Is there a "cap" that you recommend to use with that setup? And what recoil spring should be used with that combo?

 

thanks again for the wealth of knowledge you are sharing here.

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On 7/14/2017 at 11:47 AM, Maxamundo said:

 

Yes. If you call JP they will sell you individual springs for $8 each instead of having to buy the whole pack for $40.

The extra tungsten weight is optional but I found I liked it maxed out with tungsten. The theory is short travel leads to fastest dot recovery and trigger reset. But also hits your shoulder harder so it lessens the benefits. To counteract that we add the 2nd spring (instead of just solid spacer) to increase cushioning and extra weight to slow down the cycle speed and smooth it out. The mainspring we switch to a lighter one because dot recovery depends as much a softer return to battery as it does on a softer bottom out. Because of the extra spring taking up space, you'll get some pre-compression of the mainspring so the 85% might perform like a 95% and so on.

 

Everyone's gun and ammo and shooting stance is different, so I can't give you the answer to what's best for you. Unfortunately there is no single answer and everyone should do a little experimenting. 

 

Thanks for the heads up! I will have to do some tests myself soon.

 

As for adding that Smalley wave spring, that's essentially short stroking the gun right? Would the last round bolt hold open still work after this mod?

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Took my rig to the range Friday and match in Saturday. Using 130pf ammo and the jpscs with 90% spring, 3 SS & 1 tungsten weights. The bullets are 147 flat nose bayou bullets. The gun ran flawlessly and the dot movement is minimal. Practing double taps at 35' I am able to keep them well within the A! I'm pretty happy with it now. 

 

I still plan to work on the barrell extension like Max showed. And I'm going to change from N320 and work up a load with a slower burning powder and see what else I can do. 

 

Any suggestions on slow burning powder?

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On 7/13/2017 at 7:52 PM, Maxamundo said:

teGKplN.jpg

 

Interally my buffer system looks almost identical to this, except I use an inverted delrin .223 buffer instead of this custom cut milspec one with bumper.
 

 

Max, any idea if anyone is offering the bumper like above.  I did find the wave spring (free sample) but not sure what to do for a buffer/bumper.  (The blue part that the wave spring rides against.

 

Edited by 10cup
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Max, any idea if anyone is offering the bumper like above.  I did find the wave spring (free sample) but not sure what to do for a buffer/bumper.  (The blue part that the wave spring rides against.
 

It's just a cut down mil-spec buffer.


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