Jp Adjustable Gas Block

[Brian Payne]

Just purchased a used JP-15.

Owner did not have the tool kit that came with the weapon. Does anyone know the size of the allen wrench needed for the adjustment on the gas block? None of my normal ones work.

Very nice rifle.

Payne

[ken hebert]

Mine's a 5/64.

[maineshootah]

Mine's a 5/64.

How well does the adjustable gas block "really" work?

I have a few club members who are looking at getting them..... however, with out experience, it is a bit hard to pass an opinion.

[ken hebert]

Boy, those members with more expierence here really need to speak up. But, having said that I'll give my $0.01 (yes, my opinion isn't even worth the other penny). So far, in conjunction with the JP LMOS and Bennie Cooley comp I have the softest shooting, albeit the loudest, AR I've ever expierenced. I feel that the adj gas block will allow me, if I ever change loads from what I've tuned it with now, to achieve that same level of recoil. I feel I've not wasted my $$$ on the product, and when I build my next AR it will have one on it.

[stingerjg]

I have a low mass carrier and the adjustable gas block on my new AR. Other than the noise from the comp, i cant tell the difference between it and shooting a 22LR. I haven't tried it w/ the stock carrier so i cant comment on the benifits of the gas block on a stock set up. W/ the low-mass carrier it is by far the lightest shooting AR that i have experienced.

[norbs007]

Most certainly that you'll get pretty much the same response from owners as the system really works. Like what Ken said, you can tailor the recoil impulse with whatever load you use to have a very soft shooting rifle. My only dislike is that you have to Loctite everytime you adjust.

[George]

I will put in my .0015 and observations on others choices.

I have the LMOS system in my main competition AR and feel it works as advertised. It is important to have a muzzle brake on the rifle before adding the adjustable gas block if you want to see the difference tuning the gas pulse can make. Without the brake, the existing muzzle climb can mask any effect to all but the most experienced AR shooters.

Second point about adjustable gas blocks. Unless you have a shortened gas system that delivers an overly aggressive and earlier than normal gas pulse, lowering the amount of gas delivered to a NORMAL weight bolt carrier system is a moot point. The JP adjustable gas block when used on a full length gas system rifle with a full weight bolt carrier is best run wide open because this system needs full gas for reliability when dirty and running slightly less hot ammunition.

The JP LMOS is a fully integrated system that uses the gas block to properly drive a lightened bolt carrier system that requires LESS gas to not be over-cycled. In the situation where excess gas exists due to either a shorter gas system delivering a larger than normal pulse to a normal weight carrier, or a normal gas system delivering a standard pulse to a lightened carrier, the job of the adjustable gas block is to remove over-cycling stress from the system.

The standard length gas system driving a standard weight bolt carrier system can be very slightly softened by down-tuning the gas pulse, but the effect that can be had is slight and will close up the reliability window if you are not careful.

IMHO, the adjustable gas block is best appreciated when a muzzle brake is installed to allow the bolt reciprocation to be isolated, then a full JP LMOS (Low Mass Operating System) is installed to lighten and dampen this reciprocating force.

In other words, I believe that the JP adjustable gas block is a solution looking for a problem when just added to any AR with a full length gas system and standard weight bolt carrier system.

Last point: There are a few shooters who use the LMOS and choose to NOT turn down the gas and run it wide open. They are receiving some effect from the lightened carrier, but are also accepting a bit of bolt slamming as the carrier forcefully stacks the spring and then stops abruptly rather than just coming to a stop as the buffer/spring is just hitting it's stack point. This is what the tuning is all about and where the entire "whole enchilada" can be had!

[stiracer]

I will put in my .0015 and observations on others choices.

I have the LMOS system in my main competition AR and feel it works as advertised. It is important to have a muzzle brake on the rifle before adding the adjustable gas block if you want to see the difference tuning the gas pulse can make. Without the brake, the existing muzzle climb can mask any effect to all but the most experienced AR shooters.

Second point about adjustable gas blocks. Unless you have a shortened gas system that delivers an overly aggressive and earlier than normal gas pulse, lowering the amount of gas delivered to a NORMAL weight bolt carrier system is a moot point. The JP adjustable gas block when used on a full length gas system rifle with a full weight bolt carrier is best run wide open because this system needs full gas for reliability when dirty and running slightly less hot ammunition.

The JP LMOS is a fully integrated system that uses the gas block to properly drive a lightened bolt carrier system that requires LESS gas to not be over-cycled. In the situation where excess gas exists due to either a shorter gas system delivering a larger than normal pulse to a normal weight carrier, or a normal gas system delivering a standard pulse to a lightened carrier, the job of the adjustable gas block is to remove over-cycling stress from the system.

The standard length gas system driving a standard weight bolt carrier system can be very slightly softened by down-tuning the gas pulse, but the effect that can be had is slight and will close up the reliability window if you are not careful.

IMHO, the adjustable gas block is best appreciated when a muzzle brake is installed to allow the bolt reciprocation to be isolated, then a full JP LMOS (Low Mass Operating System) is installed to lighten and dampen this reciprocating force.

In other words, I believe that the JP adjustable gas block is a solution looking for a problem when just added to any AR with a full length gas system and standard weight bolt carrier system.

Last point: There are a few shooters who use the LMOS and choose to NOT turn down the gas and run it wide open. They are receiving some effect from the lightened carrier, but are also accepting a bit of bolt slamming as the carrier forcefully stacks the spring and then stops abruptly rather than just coming to a stop as the buffer/spring is just hitting it's stack point. This is what the tuning is all about and where the entire "whole enchilada" can be had!

Very Very well said George!!!!!..........That was definately a good un-biased opinion from someone who obviously uses the product and understands the system!

Edited December 29, 2006 by stiracer

[Brian Payne]

Thanks for the information.

Payne