Build-It-Yourself & Gas Block

[bob4432]

I have noticed that a lot of the build-it-yourself uppers use adjustable gas blocks. Why is the reasoning? Do the non-adjustable units permit too much gas and possibly stress on the bolt, carrier, spring & tube?

[mongoosesnipe]

depending on yours system and load it is not necessary but as the grendel pushes the limits on the ar platform many people like to tame the gas a little for a durability factor

additional as most of use are running ours as target hunting setups the small sacrifice of margin of reliability at not being over gassed by a fair margin

running at the minimum gas flow is easier on the gun and brass but it is not necessary none of the AA guns come standard with adjustable gas systems but when your chasing seconds of an angle instead of minutes ever little bit counts

[am4966]

It's just easier to fine tune the ejection, operation and helps with use with cans. Since more and more states are becoming
Silencer friendly. But that's not the only game in town anymore. You have the adjustable Gas key and bolt carrier.

[bob4432]

How hard is a fully gassed ejection on the brass? My setup will be a 16" AA Mid-Length barrel with a yhm-9384 gas block. Nitrided carrier & AA hard use bolt. I will be punching paper using PF & Hornady ammo and will be learning to reload via a friend with probably 50yrs experience reloading - he is a safe reloader and is not going to try to push it just "to get a little more", he is very conservative. But this will be a new caliber in a new platform to him. I plan on posting the powders, primers & bullets up once I have the list complete - been suffering from migraines for quite a bit lately but want to get the list together. I just want to make sure the brass is kept prime as it is a bit pricey. Will be using bullets lighter than 130gr, probably the 123 AMAX will be the heaviest (depending on accuracy).
But if putting on a $100 adj gas block means protecting the investment in brass (believe Lapua - PF Ammo claims this but also says it is AA stamped too, which I thought was Hornady brass now - can anybody clear this up) it is a no brainer.
Are any gas blocks better than others? I have seen Odin & SLR to be pretty popular.
Thanks in advance for any suggestions,
Bob

[204 AR]

I use that exact gas block on several builds because I don't like set screw blocks anymore. I actually noticed an accuracy difference when I took a set screw block off and put the yhm on. But, I modify that block with a set screw to make it adjustable. If you're handy with stuff like that, drill and tap for a #8 set screw through the side and right through the gas port hole. I install the gas tube first as you will go through the very bottom edge of it also.

The tricky part is getting the hole threaded deep enough. A blind hole tap to finish it would be great but haven't found one yet. And go slow and don't break the tap, I did that once and it's impossible to remove it.

[bob4432]

I use that exact gas block on several builds because I don't like set screw blocks anymore. I actually noticed an accuracy difference when I took a set screw block off and put the yhm on. But, I modify that block with a set screw to make it adjustable. If you're handy with stuff like that, drill and tap for a #8 set screw through the side and right through the gas port hole. I install the gas tube first as you will go through the very bottom edge of it also.

The tricky part is getting the hole threaded deep enough. A blind hole tap to finish it would be great but haven't found one yet. And go slow and don't break the tap, I did that once and it's impossible to remove it.

I chose these because they did not break the bank and were not set screw (but non adjustable) as I read about an accuracy change when using set screw type gas blocks. Thought about if for a while and it did make sense if you are putting pressure directly onto any part of the barrel, to what amount I do not know.

Would you mind taking a few pics of your mod, I just want to make sure that what I am picturing in my head is exactly what you described. No hurry of course, it is as hot as hell here (looking @ 120F on Monday ) so building time for me.

Thanks in advance,
Bob

[204 AR]

A little grainy on the picture but you get the idea. It looks just like any other adjustable gas block when you're done. A good reasonable alternative is the BTE adjustable clamp on block. I think they're under $50.

[bob4432]

A little grainy on the picture but you get the idea. It looks just like any other adjustable gas block when you're done. A good reasonable alternative is the BTE adjustable clamp on block. I think they're under $50.

Appreciate it greatly
Thanks, Bob