Help! AR15 lightweight BCG question.

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soforcy

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Hi,

A gunsmith told me that rifle length gas system has the lowest pressure so using a lightweight BCG without adding an adjustable gas block should work. While some people told me an adjustable gas block is needed with a lightweight BCG.

I’m wondering if any of you have ever used a lightweight BCG on a rifle length gas system platform without adjustable gas block? Will it work if I only swap out the BCG to a lightweight one? I’m totally new to this so please forgive me if this is a repeated topic.

Thanks,
Edward
 
I`m curious about this as I plan to do similar

My guess would be that the BCG will cycle fine with a rifle length gas system however from what I have read some lightweight BCG manufacturers advise to use an adjustable gas block so as to turn down the gas to the smallest amount that will cycle the gun, that way you are putting the least amount of stress/wear on the lightweight (probably aluminum) BCG

Doing this will also reduce the felt recoil to the lowest possible

This is my understanding - others more knowledgable than me will hopefully chime in as I plan to do similar and want to get it right
 
A regular weight BCG works fine with a rifle length gas gas system (in fact it was designed to work that way). An adjustable gas block just lets you tune things and make them perform a little more optimally but they are far from needed if the gas port is a correctly sized and you use a normal weight buffer.
 
If your rifle cycles early with the lighter bolt you would see more buildup of carbon and dirt around the BCG. An adjustable gas block could help, so would a slightly heavier buffer or buffer spring, but in all honesty, you likely will not need to do anything.
 
If you tune your rifle with a light weigh BCG and an adjustable gas block you should be aware that the ammo choice becomes very limited. Preferably you stick to ONE type of ammo.
 
soforcy said:
Hi,

A gunsmith told me that rifle length gas system has the lowest pressure so using a lightweight BCG without adding an adjustable gas block should work. While some people told me an adjustable gas block is needed with a lightweight BCG.

I’m wondering if any of you have ever used a lightweight BCG on a rifle length gas system platform without adjustable gas block? Will it work if I only swap out the BCG to a lightweight one? I’m totally new to this so please forgive me if this is a repeated topic.

Thanks,
Edward
Click to expand...

If you are trying to do a LW BCG without an adjustable gas block, then yes a rifle length gas is the best choice, and yes it will work. It just won't be optimal until you switch to an adjustable gas block to tune the cycling.

I would estimate probably half of the gain is from the adjustable gas, and half is from the LW BCG.

This is where I shamelessly plug the uppers I have for sale in the EE, which feature LW BCGs, adjustable gas blocks, and rifle and intermediate length gas systems on high-end barrels. Best deal on this kind of gear in the country.
 
Adjustable gas blocks are the first thing you should buy for a custom build, Even more so with a lightweight BCG !

I can't remember the last time I built an AR without one.
 
DILLIGAF said:
Adjustable gas blocks are the first thing you should buy for a custom build, Even more so with a lightweight BCG !

I can't remember the last time I built an AR without one.
Click to expand...

I actually just placed order for a adjustable gas block minutes ago...
Seems like I should consider lightweight buffer as well haha.
 
soforcy said:
I actually just placed order for a adjustable gas block minutes ago...
Seems like I should consider lightweight buffer as well haha.
Click to expand...

Nope, a regular buffer is just fine. Don't stray from "standard/milspec" unless there is a desire or a need. The farther you stray, the more you may have to tinker to make things work reliably. Stock, AR's are overgased, you putting in an lightweight BCG makes your gear even more overgased. Toss in a light buffer and you are even more overgased (while a heavier buffer would negate the point of a lightweight BCG it would bring things more in spec/normal).

A stock BCG and a stock gas system is overgased, going too far causes weird #### like bolt bounce, which leads to reliability issues that people don't understand /can't fix because they don't know what's wrong.
 
mustang979 said:
Nope, a regular buffer is just fine. Don't stray from "standard/milspec" unless there is a desire or a need. The farther you stray, the more you may have to tinker to make things work reliably. Stock, AR's are overgased, you putting in an lightweight BCG makes your gear even more overgased. Toss in a light buffer and you are even more overgased (while a heavier buffer would negate the point of a lightweight BCG it would bring things more in spec/normal).

A stock BCG and a stock gas system is overgased, going too far causes weird #### like bolt bounce, which leads to reliability issues that people don't understand /can't fix because they don't know what's wrong.
Click to expand...

How about LW BCG pair with adjustable gas block, then reduce the weight of buffer?
 
soforcy said:
How about LW BCG pair with adjustable gas block, then reduce the weight of buffer?
Click to expand...
Could it work, sure, in fact with a decent adjustable gas block it should work (you may get bolt bounce). May I ask why? It's not like you have a fully automatic system and are chasing a certain cyclic rate. When I set my AR's to run, I aim for them to be smooth and reliable, I'm not quite certain what you are chasing.
 
mustang979 said:
Could it work, sure, in fact with a decent adjustable gas block it should work (you may get bolt bounce). May I ask why? It's not like you have a fully automatic system and are chasing a certain cyclic rate. When I set my AR's to run, I aim for them to be smooth and reliable, I'm not quite certain what you are chasing.
Click to expand...

At the beginning I just simply want to reduce some weight so I choose a LW BCG and its TiN coated. And then people suggested me adding an adjustable gas block to compensate the LW BCG. Although without adjustable gas block, the rifle would work fine, I still purchased the adjustable gas block just in case.... and I have LW BCG and adjustable gas block... I’m think take some weight off the buffer and limited gas flow to reduce the recoil feeling...

Idk I’m totally new to this...so my opinion change fast haha
 
I wanted less weight total but more specifically I wanted less reciprocating mass so I went with all of it.
Low mass BCG, Odin adjustable gas block and Taccom lightweight buffer and spring. I think the buffers may be a fairly new idea but so far I am liking it. I use a Precision Armament m-11 muzzle brake as well. My thought is to keep the rifle on target more than anything. Once you are adjusting the gas you are adjusting the gas and the idea is that the less weight and gas back is a good thing for smooth cycling....Maybe I am wrong. I use the same bulk ammo so I'm not too concerned about variability with different ammo and I keep my guns fairly clean. I have 2 sporter uppers on order so 1 will be handloads and the other bulk. I don't think I'll have to worry about reliability since it's been running fine on my PSA 10.5" and the MDI SLR.
Just my 2c
 
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