Question about diameter of gas blocks and internal diameter of hand guards

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leakproofpuma7

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Looking at getting a Rainer Arms Night Rail Hand Guard. Thinking barrel would be .750 gas block size.

Now the Internal diameter of hand guard measures 1.37inchs from what it says and I can't find any adjustable low profile gas blocks that are smaller than 1.37 inches. Just wondering if anyone else is running a similar internal diameter handguard and what adjustable gas block they're using.

Thanks
 
Maybe move away from adjustable?

I just bought a clamp on that doesn't fit inside a BCM kmr. Found out the hard way. Any low profile 750 fits inside it though.
 
Light weight bcg and thinking of going mid length for gas so adjustable is needed I'd think. I know some people are using the rainer Arms night rail and .750 just wondering what they're using
 
TNA carries some low profile adjustable gas blocks that are 1.35" high and migt fit your handguard. They carry the TNA line as well as Ergo and some other brand which you'd want to avoid due to poor design location of the adjustment screw. Syrac also makes a very low profile gas block that is front adjustable. The TNA ones had a little bit of a shoulder to them. The Ergo and Syrac have less of a shoulder.
 
I think I found three but not sure of height.

Why is that if they do state any measurement it's usually only the length and width not the height.

These three are the only adjustable low profile gbs I found

https://truenortharms.com/ar15_defa...ustable-gas-block-steel-low-profile-0-75.html

This one doesnt say what size eg: .750 or .625 etc
https://truenortharms.com/ar15_default_store_view/tna-elite-series-adjustable-gas-block.html

And

https://truenortharms.com/ar15_default_store_view/ergo-adjustable-gas-block-0-75.html

Of those three which would you choose?

Thank you
 
leakproofpuma7 said:
I think I found three but not sure of height.

Why is that if they do state any measurement it's usually only the length and width not the height.

These three are the only adjustable low profile gbs I found

https://truenortharms.com/ar15_defa...ustable-gas-block-steel-low-profile-0-75.html

This one doesnt say what size eg: .750 or .625 etc
https://truenortharms.com/ar15_default_store_view/tna-elite-series-adjustable-gas-block.html

And

https://truenortharms.com/ar15_default_store_view/ergo-adjustable-gas-block-0-75.html

Of those three which would you choose?

Thank you
Click to expand...

I wouldn't touch ANY of the gas blocks you listed if you intend to cover them with a handguard. They all have the adjustment screws on the side. Depending on the handgaurd you will most likely have to remove it to make adjustments. They also don't list the height of the gas block, which is the most critical for fitting under a handguard.

I'd recommend a forward adjusting gas block. Like a SLR Rifleworks, Superlative Arms or Odin. Go look at the SLR rifleworks website, they have a picture for each gas block with actual dimensions.
 
mileageman said:
I wouldn't touch ANY of the gas blocks you listed if you intend to cover them with a handguard. They all have the adjustment screws on the side. Depending on the handgaurd you will most likely have to remove it to make adjustments. They also don't list the height of the gas block, which is the most critical for fitting under a handguard.

I'd recommend a forward adjusting gas block. Like a SLR Rifleworks, Superlative Arms or Odin. Go look at the SLR rifleworks website, they have a picture for each gas block with actual dimensions.
Click to expand...

I believe most handguards allow for at least a standard gas block height?
 
For that one yeah scrolled down to the bottom and clicked more information. 2nd one you have to find out the non adjustable versions height and itll be the same.
3rd one they say the similar thing about height but can't find the non adjustable gas blocks height either.

Below, posting the two heights. Thanks for the help, think I've settled on one.

1st - 33mm / 1.299inches
2nd - 34.29mm / 1.35inches
3rd - Not sure
 
the Odin adjtable Gas Block will fit inside BCM KMR/Mlock but tight, the Odin O2 Lite is good with their adjustable GB.
 
ffgats said:
the Odin adjtable Gas Block will fit inside BCM KMR/Mlock but tight, the Odin O2 Lite is good with their adjustable GB.
Click to expand...

Googled it and the odin adjustable gas block is 1.41. And I read that a BCM MCMR is 1.3 internal diameter not sure if mcmr is the same ID as your KMR.

If it is then that's weird how it'll fit.
 
The KMR and has Mlok the same ID , maybe the you are looking at the height of the GB and not the height of the forearm.
 
thegrandpoohbah said:
You sure about that? If there isn't that valley at the top how is the gas tube going to fit even if you find a gas block that will fit?
Click to expand...

+1 if I am not mistaken the Rainier arms night rails are the same, and most likely even made by Fortis for RA. And just made for and branded Rainier Arms Night rail instead of Fortis Night Rail
Even on Rainier Arms site they link a video to a Fortis night rail install for the installation of their night rails, so ya I am pretty sure about that one

If so they clearly have that valley like almost any other AR rail

FTS-NIGHT-556-KM_2__56922.1504119990.JPG
 
JohnnyP636 said:
+1 if I am not mistaken the Rainier arms night rails are the same, and most likely even made by Fortis for RA. And just made for and branded Rainier Arms Night rail instead of Fortis Night Rail
Even on Rainier Arms site they link a video to a Fortis night rail install for the installation of their night rails, so ya I am pretty sure about that one

If so they clearly have that valley like almost any other AR rail

FTS-NIGHT-556-KM_2__56922.1504119990.JPG
Click to expand...

That's the Fortis Night Rail. You are correct Fortis and Rainer worked together to create the "Rainer Arms" Night Rail, their verison removes a lot of the picitany railing on the top and all around the middle.

Now seeing this picture and looking at the rainer arms one, I think it does have the valley...

When they post the ID of a rail does that not include the top valley I'm assuming? So a ID of 1.37 could hous a larger than 1.37 high gb possibly? (Not that I'd chance it but...)
 
leakproofpuma7 said:
That's the Fortis Night Rail. You are correct Fortis and Rainer worked together to create the "Rainer Arms" Night Rail, their verison removes a lot of the picitany railing on the top and all around the middle.

Now seeing this picture and looking at the rainer arms one, I think it does have the valley...

When they post the ID of a rail does that not include the top valley I'm assuming? So a ID of 1.37 could hous a larger than 1.37 high gb possibly? (Not that I'd chance it but...)
Click to expand...

Diameter means a circle. Is the valley a circle? No. The ID of the rail, meaning the circular portion, may well be 1.37, but the height is substantially more.
 
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