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JP rifle buffer setup?


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Hello: I have a friend who just got a new JP 9mm rifle. It ate every ammo loads we tried. With the stock JP silent buffer setup it seems to get a lot of dot movement with his 147 and my 124 loads. What setup are you guys using to tame the dot movement? I have a JP buffer and bolt coming so I am curious as well. I was thinking lighter spring and maybe changing some weights. I was also thinking of making an aluminum weight as well so various weight setups could be tried. Let me know your setup so we can get some parts ordered. Only other changes I would do if it was mine is an extended mag release, lighter hand guard and maybe a stock change. But other than that it is a shooter. Thanks, Eric

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I just installed the Blitzkrieg Components 9mm Hydraulic buffer and JP 308 rifle spring.  I have only shot 50 rounds this afternoon, but so far I'm liking it.  Very fast double taps at 10 and 15 yards keeping both in the A zone.

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Two of my friends have the JP GMR-13 rifles, and the dot movement on them is minimal with the 4 different loads I tried. I have an ATI 9mm AR that had major dot bounce with the stock buffer, until I got the JPSCS2-9 buffer. It was much improved but still not as good as my friends' rifles until today. I ordered the same JP muzzle brake that is on their rifles, and that was the magic bullet for me. At 15 yards I can double tap a 8" round plate as fast as I can run my 3.5lb POF trigger, and the dot never leaves the plate. It moves maybe 2.5" or so max at that distance. I was shooting some clays at 20 yards on a berm, and accidentally bump fired it and both rounds impacted where the clay had been. I couldn't ask for much more than this.

Actually that's not entirely true- I could ask for more. I could and would ask ATI that they use better screws on the gas key so this didn't end my day today:
550201c3e85f18af5126ab7d95176b62.jpg

At the end of a string I noticed something in the ejection port, and after opening the upper I found the gas key sheared off! I got the broken screws out easily since there was no Loctite on them. Ordering grade 8 bolts for it now.


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15 hours ago, 1911luvr said:

Two of my friends have the JP GMR-13 rifles, and the dot movement on them is minimal with the 4 different loads I tried. I have an ATI 9mm AR that had major dot bounce with the stock buffer, until I got the JPSCS2-9 buffer. It was much improved but still not as good as my friends' rifles until today. I ordered the same JP muzzle brake that is on their rifles, and that was the magic bullet for me. At 15 yards I can double tap a 8" round plate as fast as I can run my 3.5lb POF trigger, and the dot never leaves the plate. It moves maybe 2.5" or so max at that distance. I was shooting some clays at 20 yards on a berm, and accidentally bump fired it and both rounds impacted where the clay had been. I couldn't ask for much more than this.

Actually that's not entirely true- I could ask for more. I could and would ask ATI that they use better screws on the gas key so this didn't end my day today:
550201c3e85f18af5126ab7d95176b62.jpg

At the end of a string I noticed something in the ejection port, and after opening the upper I found the gas key sheared off! I got the broken screws out easily since there was no Loctite on them. Ordering grade 8 bolts for it now.


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Well that is interesting. I had two KVP bolts fail in exactly the same manner. They suspected the side charging upper so I sent the whole upper to them to check out. I am running a JP spring as well.

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Well that is interesting. I had two KVP bolts fail in exactly the same manner. They suspected the side charging upper so I sent the whole upper to them to check out. I am running a JP spring as well.


I just put the NFA side charge upper on this rifle and this was the first day shooting it. I found no peening marks on the charging rod or the gas key so I didn't think it was the upper. However, after hearing about yours you now have me thinking. Let me know what they find out!


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3 hours ago, 1911luvr said:


I just put the NFA side charge upper on this rifle and this was the first day shooting it. I found no peening marks on the charging rod or the gas key so I didn't think it was the upper. However, after hearing about yours you now have me thinking. Let me know what they find out!


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I am running the NFA side charge too. 

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Hello: I will say my light setups shoot flatter than the stock JP does at this point. I am just curious for a starting point for the JP silent buffer. Thanks, Eric


What muzzle device are you running? I am running the JPSCS2-9 in stock configuration, but I was considering going heavier before I changed my brake. I called JP and got the info to order the weight and spring kit, but decided to wait until the brake arrived before making any buffer changes. After swapping my stock birdcage comp (bottom facing area has no openings) for the JP brake, I have no need to change any of the buffer components. Dot rise is minimal now.


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Hello: I tried using 2 steel and 2 tungsten weights with the stock spring. It seems to have less dot movement and good splits at 10 yards. I will try some different springs and maybe take one more tungsten weight out. I am using 124's and 147's both at 131-134PF. Thanks, Eric

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  • 4 weeks later...
On 1/16/2017 at 7:22 PM, JRM83 said:

Well that is interesting. I had two KVP bolts fail in exactly the same manner. They suspected the side charging upper so I sent the whole upper to them to check out. I am running a JP spring as well.

 

KVP thought the issue was with the side charging NFA upper. I asked them to replace it with their slick side upper. Only about 200 rounds through it so far, but all of the feeding issues I had are gone and it's running well. Time will tell if it's going to break another bolt, but I don't think it will.

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Hello: More testing with 3 steel weights and one tungsten. I am using the green spring from the 223 spring kit. I am also using 2 steel and 2 tungsten weights with the white spring from the 223 kit. These are with 131-133 power factor 147 loads in a 16" barreled rifle. Bolt is a JP and Matrix. Thanks, Eric

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Just FYI, I have seen 3 AR9 BCGs with loose gas key bolts, one of those sheared off the rear bolt. One was a side charger and the other two standard. I think the problem is in the staking of the bolts, not the type of charging handle.

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Hello: More testing with 3 steel weights and one tungsten. I am using the green spring from the 223 spring kit. I am also using 2 steel and 2 tungsten weights with the white spring from the 223 kit. These are with 131-133 power factor 147 loads in a 16" barreled rifle. Bolt is a JP and Matrix. Thanks, Eric


So how does the 2 tungsten and spring compare to the 3 tungsten and spring?


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On February 10, 2017 at 7:53 PM, 1911luvr said:


So how does the 2 tungsten and spring compare to the 3 tungsten and spring?


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Hello: It shoots flatter for me with the 2 tungsten and 2 steel than the 3 tungsten and 1 steel with the 308 heavy spring. Going to do more testing since I have 2 silent buffers and also try a friends stock buffer at the same time with my loads. Thanks, Eric

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  • 4 months later...
On 2/11/2017 at 8:55 PM, Aircooled6racer said:

Hello: It shoots flatter for me with the 2 tungsten and 2 steel than the 3 tungsten and 1 steel with the 308 heavy spring. Going to do more testing since I have 2 silent buffers and also try a friends stock buffer at the same time with my loads. Thanks, Eric

Eric, sorry for bringing up such an old post, but I'm curious where you've landed with your silent setup? 

 

I just got my gen 2 scs in today and am curious to learn from others.

 

My gun is ATi milsport, 16" barrel, 3lb trigger and as of now a bone stock jpSCS with 3 tungsten/1 steel weight and the red spring.

 

I will be shooting 147gr bayou bullets (but have yet to try any loads). From reading various posts here I'm thinking 3.0gr n320 and OAL of 1.085 should be a good starting point to achieve 130ish.

 

Amyway, where you at with buffer configuration?

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Hello: I actually have two different setups depending on what lower I am using. For the Glock lower I am using 3 steel weights and one tungsten with the green spring. On the Colt lower I am using 2 tungsten, 1 steel and 1 aluminum I made with the black spring. I use a timer and targets set at 7 yards to see what my splits are and hits look like. Some around here are just using the stock setup and shoot them very well but for me the lighter setup it faster and softer. Thanks, Eric

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