Jp full mass or low mass carrier?

[mumzer]

From personal experience...

I run a LMOS bolt carrier and a silent capture spring in my JP 6.5G. Never a failure to feed or short stroke. Runs like a top, suppressed or unsuppressed. I have an adjustable gas block as well but have never had to use it.

which spring?

[81police]

which spring?

The original, standard version, GEN I

[Klem]

Mumzer,

Thank you for your response.

I was not trying to be condescending earlier as I am often the victim of the 'newest shiniest thing' myself. I ran out an bought a piston upper kit when they first came out and also the Blackout when that first came out in 16" barrels and carbine-length gas. At the time the Blackout was being touted as the potential replacement for the 5.56. I admit the Blackout has its subsonic niche but all the marketing hype of being able to penetrate 20 milk jugs belies its actual effect on flesh, which I found out the hard way. It often overpenetrates, has less hydrostatic shock, its max effective range on supersonic is less than 5.56 and the rounds are twice as heavy (three times heavier for subsonic), and more expensive for less ability to kill. I use it exclusively for plinking and occasional subsonic hunting now but mostly it sits in the safe.

Your understanding of how much gas is generated across three calibres assumes all things being equal, like where the gas block is situated along the barrel. Gas at the port is a function of the load, the barrel volume (larger volumes drop quicker) and where along the barrel the port is situated. This gas is then further regulated by fixed diameter ports and more recently the introduction of adjustable gas blocks. Then tamed by recoil springs and different buffer weights. Introducing low mass carriers (LMC) as yet another mechanism for regulating gas and reciprocation is arguably unnecessary given all the other mechanisms available. Using LMC's for reciprocation taming also risks introducing the problems mentioned earlier; lack of mass to strip rounds from tight mags and failure to go into battery when filthy.

If however you want to use an LMC in order to lower the reciprocating mass. This in the expectation it will tame bolt slam (which in turn affects accuracy...no argument there) then you risk the two problems mentioned above - Quid pro quo.

1. It is my opinion than LMC's might be the latest gimmick to hit the market.

2. Any advice given by an employee regarding their products is a potential conflict-of-interest. That should not stop us from seeking it and filtering their advice for unbiased assistance.

If you wish to reply then please do however this will be my last word on this thread.

[mumzer]

Sigh...yah...nevermind.

[LRRPF52]

Let's keep it technical.

You can use either a full mass or a low mass carrier.

It just depends on how you gas and spring the system. The JP SCS can be configured with various spring and buffer weights to balance and tune everything if needed.

[schrödinger's cat]

I've got to say Mumzer, you sound like a very knowledgable guy, and with over 10,000 rounds in just one of your guns you shoot a lot more than I do. But common Internet forum etiquette is that although you certainly are entitled to disagree with anyone, and you may in fact have much better information, but when you are new somewhere and you are disagreeing with someone that has been here for a long time, has a lot of posts, and is one of the more helpful contributing members, that you try to disagree in a non argumentative non confrontational way. This will make you a better respected member and will make you more likely to be someone who's advice is asked and taken. And I've got to say your posts come across as a bit rude, I'm sure you didn't mean for them to seem that way, and you may have thought that Klem's posts were passive aggressive, but when you stick around a little longer, and read more of his posts, you'll see that this was not the case.
Welcome to the forum we are glad to have you here and I look forward to learning a lot from you !

[mumzer]

Thanks for the welcome...its more of a re-welcome. I was active here a year or two ago and deleted my account when I briefly got out of Grendels. I'd moved to my bolt guns for a while, but to be honest, nothing else feels as natural as the ar platform after so many pew pews downrage.

The 10k rounds are through a carbine that i use when I teach. I'd like to say that you should always "beware the man with just one gun - he probably knows how to run it," but i still have lots to learn as well.

[keystone183]

OP.......purse swinging and wordy posts aside.....

I also run a LM with SCS and an SLR adjustable block. On a 12.5" midlength suppressed i have it open 4 clicks, i believe. Yet to experience a malf running all factory hornady and PPU. Sample size is around 500. I briefly ran that system on a 20" midlength gun and had same results although with far fewer rounds. I have no doubt that taking off the suppressor, i could open up that gas block, and experience the same reliability, with room to spare. Pleasure to shoot. Go for it.

Also, i have but have not yet run, an AIM Low mass bolt. It looks great, fit and finish. I suspect it will run the same.

Sorry for the wordy post....

[Rob57]

OP - don't want to hijack the thread - I think my question is related - apologies if you don't think thats the case.

I've just ordered a JP 6.5G and because I'm going to run suppressed the advice I got was to run the FMOS and heavier SCS. Looks like some of those posting here are running the LMOS with a suppressor in which case it'd be great to know more about their experiences.

Please let me know if I need to delete and repost - I'm new here.

Thank you -

[keystone183]

OP - don't want to hijack the thread - I think my question is related - apologies if you don't think thats the case.

I've just ordered a JP 6.5G and because I'm going to run suppressed the advice I got was to run the FMOS and heavier SCS. Looks like some of those posting here are running the LMOS with a suppressor in which case it'd be great to know more about their experiences.

Please let me know if I need to delete and repost - I'm new here.

Thank you -

LMOS with adjustable block. If yours doesn't have adjustable block, then FMOS may be the way to go.

[Rob57]

Thanks. I did spec an adj gas block. I might just get back on the phone with the guys at JP.

[A5BLASTER]

Good idea calling JP their customer service is top self.

A point of advice you can double check with JP if you like, When I was putting my upper together I was having gas block alinment problems and I spoke to them and they told me their barrels gas port is cut so the gas block has to be hard against the shoulder for the gas block to line up properly.

I got one of their split yoke adjustable blocks with the gas tube installed at the factory and maybe its just me but I had a much easyer time getting it all lined up that way.

Hope this info helps sir.

[81police]

I'm running a LMOS and Gen I silent capture spring...also an adjustable gas block though I haven't needed to use it. Runs like a top, kicks like a 223, hits like a 243