JP Silent Captured Spring ... H2 or Standard for Grendel?

[Shooter Magavin]

Greetings to the Horde,
I'm building my first 6.5 Grendel. I'm using a 20" Faxon Match Fluted Heavy w/RLGS barrel, WMD NiB full-mass BCG, and SLR's Adj gas block.

I've used JP's Standard Silent Captured Spring (JPSCS2-15) with a Low-mass bolt in a 5.56 build and I liked it enough to want another for this rifle.
However, according to JP's flow chart, I need an H2 version for the Grendel. For those of you that have used the JPSCS...has this been your experience. Is the heavier buffer necessary or even preferred?

Thanks

[A5BLASTER]

I'm still useing the gen 1 scs in my 20 inch with rifle gas, have used it with 18 inch rifle gas and 16 inch with mid gas and with a lowmass bcg and full mass m16 profile bcg I see no reason to get the heavier scs.

It's a system as you found out with the 223, it needs to be used as a full system to get the most use out of it.

Scs normal weight, adjustable gas, lowmass bcg and muzzle brake make for a super soft shooting rifle.

Also get the spring kit, the standard spring can be changed out for a lower strength one that will also help you dial the gas down a bit more.

I talked with the guys at JP about this and used their guide and it and them said go with the heavy version, yet I know 3 people with full jp built guns and they all came with the normal weight scs and two of those are grendels.

I don't think it would hurt to go with the heavier scs but I do think you won't beable to dial the gas down as low.

Also if you need a lowmass bcg right to bear arms sells a dang good one as a stripped lowmass for bout 60 bucks.

I have one and to be honest it's on par with the JP lowmass bcg I have as well.

Hope this helps sir.

[Shooter Magavin]

Thanks A5Blaster.

"I don't think it would hurt to go with the heavier scs but I do think you won't be able to dial the gas down as low"
That's a good point I didn't consider. I am led to believe by a number of posts Iv'e read that, on a Grendel, the RLGS on a 20" bbl is nowhere near over-gassed to begin with. So the standard weight buffer should allow me more adjustment range on the gas block. Am I figuring that correctly?

I actually have JP's tuner spring kit from the last build and since I'm using the standard weight spring, I still have the full set available to use on this one.

I also agree with you on the RTB low mass carrier. I have one too. I don't own a JP low-mass but I do have a Rubber City Low-mass BCG and an A2 Armament LghtWght Adjustable BCG and, for the price, the RTB is a real value. In fact, this (the Grendel) may be the only rifle I have NOT running a Low-mass carrier. Maybe I'll change it up later. But for right now, I want to keep it a standard M-16 carrier.

Thanks for the input.. very helpful.

[A5BLASTER]

Thanks A5Blaster.

"I don't think it would hurt to go with the heavier scs but I do think you won't be able to dial the gas down as low"
That's a good point I didn't consider. I am led to believe by a number of posts Iv'e read that, on a Grendel, the RLGS on a 20" bbl is nowhere near over-gassed to begin with. So the standard weight buffer should allow me more adjustment range on the gas block. Am I figuring that correctly?

I actually have JP's tuner spring kit from the last build and since I'm using the standard weight spring, I still have the full set available to use on this one.

I also agree with you on the RTB low mass carrier. I have one too. I don't own a JP low-mass but I do have a Rubber City Low-mass BCG and an A2 Armament LghtWght Adjustable BCG and, for the price, the RTB is a real value. In fact, this (the Grendel) may be the only rifle I have NOT running a Low-mass carrier. Maybe I'll change it up later. But for right now, I want to keep it a standard M-16 carrier.

Thanks for the input.. very helpful.

It should do to it being lighter weight buffering mass it will be lighter in weight total, so it will need less spring force to slow it down when moving back on extraction and less gas to move it.

Also the weaker spring matched to a lowmass bcg will lessen the muzzle dip from the bcg returning to chamber on a fresh round, again making the guns over all recoil feel much less and much smoother.

I wish I would have found the RTBA lowmass bcg before I bought the jp bcg, would have safed me a ton of cash.

That's my thinking the rifle gas with the lighter weight buffer will give you more adjustment range on the block, unless the gas port of the barrel is cut undersized.

I'm rocking the 20 inch group buy barrel now and it's gas port size is perfect for running adjustable gas and lowmass parts.

Just a tip to help, get some locktite and bed the gas tube into the gas block meaning where the tube sticks out the block put a ring of locktite around it, one more spot to quickly stop gas leak, makes a difference.

I also bed my gas blocks with locktite to the barrel but with a clamp on or set screw type gas block that can be a pain but I use the split yoke type jp sells so it's much easier to do it, seems dumb at first but it really seems to help when setting up the gas system and getting it tuned.

[Shooter Magavin]

Actually, I used Rockset on my gas tube to block connection. I did it on the last 5.56 build i did with a Superlative Arms Bleed block and it was so gas efficient that, with the block at full exhaust (Bleed) setting, it still locked back on the last round and cycled without fail. So I had to almost completely shut the gas off to finally get it to short stroke. In other words, it made a huge difference.