Gas Blocks

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Gas Blocks

Postby wwwthekeeper » Thu Apr 19, 2018 9:55 am

Does anyone make a stainless-steel gas block with upper and lower rails?
What are the pros and cons of clamp on gas blocks and or Aluminum gas blocks?
I need an education on gas blocks as I am starting a build of a .450 Bushmaster upper using a Mid Length Gas System w/ 1:24 Twist
18" Stainless Heavy Barrel and side charged upper receiver.
Thanks for any and all help
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Re: Gas Blocks

Postby Hoot » Thu Apr 19, 2018 11:44 am

wwwthekeeper wrote:Does anyone make a stainless-steel gas block with upper and lower rails?
What are the pros and cons of clamp on gas blocks and or Aluminum gas blocks?
I need an education on gas blocks as I am starting a build of a .450 Bushmaster upper using a Mid Length Gas System w/ 1:24 Twist
18" Stainless Heavy Barrel and side charged upper receiver.
Thanks for any and all help


I've never seen a gas block with the form factor you're looking for but 've never looked for one. I will say that I prefer a steel gas block for two reasons. First, as it warms, it will have a similar expansion coefficient as the steel barrel it is clamped onto. Second, the gas being redirected out of the port is hot and under pretty high pressure. It would seem to me that aluminum would erode faster than steel, when blasted by that hot jet stream, over and over. The latter is just my gut feeling. I've used both clamp on and set screwed blocks and from my experience, they're a horse apiece. I do know that getting a close tolerance fit is important to reduce leakage around them. Notice I didn't say eliminate? That's nearly impossible.

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In Theory, there is no difference between theory and practice. In Practice, there is.
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Re: Gas Blocks

Postby Bmt85 » Thu Apr 19, 2018 2:36 pm

I have seen the gas blocks you are referring to, however, I don't recommend them. Gas blocks get hot, maybe not as hot in a 450B because we don't usually shoot high volume, but still. Last thing I would do is mount something to the gas block. I also agree with Hoot, run a steel gas block. My preference is SLR set screw blocks. They are very nice, relatively cheap, and there jigs make a perfect alignment. I have used clamp on blocks on a couple builds, and they are ok, but you do have to mess with them a bit to get them properly aligned. Mainly because the gas block has to be a small distance away from the shoulder right behind the gas port, on top of being clock right. Not terribly difficult, but it is a factor. SLR jigs take no time to set up, and it's perfect everytime.
Last edited by Bmt85 on Sat Apr 21, 2018 10:31 am, edited 1 time in total.
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Re: Gas Blocks

Postby wwwthekeeper » Fri Apr 20, 2018 3:00 pm

This is what I am going to put on my 5.56 upper, A Yankee Hill Machine AR-15 steel gas block YHM-9394 Front Flip Sight with fold down spring-loaded pushbutton front sight with a bayonet lug and pivoting sling swivel. But I will put a Stainless Steel Micro Low Profile Gas Block on the .450BM.
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Re: Gas Blocks

Postby plant_one » Sat Apr 21, 2018 10:20 am

instead of worrying about a gas block with a rail on it, why dont you install a low pro gas block and put on one of the many different modular rail system handguards and put your sights on that. that will allow you to to mount any accessories you want and not have to put a stupid cheese grater (Quadrail) onto your firearm.

most of my AR's are configured with a handguard system like this, although i employ several different product lines.

here's a pic of my 223 with a Samson evolution showing the style of rail i'm discussing.. this isnt its final configuration (pre- accessory rails, etc) but itw as the first one i found to show you what i meant. i have a 2" rail at 6 o'clock for bipod attachment all the way up front, and another at 3 o'clock for mounting my LED light for night hunting.

Image


anything you attach to your barrel (upper sight, bipod, grip, etc) via a railed gas block is going to mess with the barrels harmonics and accuracy.
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