FSB Problem Need Some Advice Please

[Jason_805]

The Problem I'm having Is my 10.5 300 Blackout Barrel I have to run a Low Profile Gas Block under the rail. At the end of the Barrel it measures .700 which I cannot find a gas block with a rail in that size. My choices are to Shim a .750 OR Ream a .625. Unless anyone knows where to find a .700 gas Block. Any Suggestions?? Thanks A lot!

[Xtracrispy]

The Problem I'm having Is my 10.5 300 Blackout Barrel I have to run a Low Profile Gas Block under the rail. At the end of the Barrel it measures .700 which I cannot find a gas block with a rail in that size. My choices are to Shim a .750 OR Ream a .625. Unless anyone knows where to find a .700 gas Block. Any Suggestions?? Thanks A lot!

You would need to measure where the gas block goes, unless you are confident there is no taper between the gas block and the end of the barrel.

What brand is the barrel?

EDIT: Are you trying to put a front sight base or similar in front of the rear gas block, or are you trying to find a lo-pro gas block? I might have misunderstood you.

[SJgunguy24]

You could always chop an A2 front sight down and put a front sight on the rail.

[baih777]

it sounds like you bought the wrong rail. you bought a extended or using a mid-length rail on a pistol build. and you bought a barrel without thinking it thru.
your setup sounds like you need to just put a Red Dot sight on it and be done.
they do make low profile flip up sights that will mount on top of the rail.

[Jason_805]

The Barrel Is an HM Defense 300 AAC 1-8 Fluted. I'm trying to upload some Pictures now. I already have a low profile gas block that sits in the middle of the barrel. That measures .750. It tapers at the end of the barrel to .700. I would like to have a A2 Front sight. Its an AR Pistol Build. I forgot to mention That.

[Jason_805]

Here's another Pic

[Jason_805]

I Either have to Shim a .750 gas block or Bore/Ream a .625.

[baih777]

you bought a 300 blackout and a pistol gas port.
good luck .
you will need this sight for the rail.

http://www.midwayusa.com/product/2319221264/magpul-mbus-gen-2-flip-up-front-sight-handguard-height-ar-15-polymer?cm_vc=ProductFinding

then you need to put the barrel on the upper and measure how long a handguard you want. when your looking for a handguard, a lot of them give the length.

I have never seen anybody mount another gas block on the end of the barrel to mount a sight. that's why you cant find one.

[Xtracrispy]

I get it now. Thats what I thought after I had already responded and re-read your post.

In my own not at all professional opinion, I think having the end of the barrel turned down to .625 would be the cleanest. You could shim a .750 block, but it may look weird if you can see where it is shimmed. As far as boring out a .625 block, I'm not sure if they have enough extra material to do that effectively, but if they do it could be done.

If you aren't dead-set on a front sight base, why not get as long of a handguard/rail as you can and put a front iron sight on the end of your quad rail?

Picture for example:

[Jason_805]

I get it now. Thats what I thought after I had already responded and re-read your post.

In my own not at all professional opinion, I think having the end of the barrel turned down to .625 would be the cleanest. You could shim a .750 block, but it may look weird if you can see where it is shimmed. As far as boring out a .625 block, I'm not sure if they have enough extra material to do that effectively, but if they do it could be done.

If you aren't dead-set on a front sight base, why not get as long of a handguard/rail as you can and put a front iron sight on the end of your quad rail?

Picture for example:

That's a good Idea! I already ordered the rail its a Midwest 7" I also like the A2 sight. I wasn't looking at this the right way. I think Ill try the A2 style first Im sure I can find someone to ream it out. Thanks again.

[Jason_805]

you bought a 300 blackout and a pistol gas port.
good luck .
you will need this sight for the rail.

http://www.midwayusa.com/product/2319221264/magpul-mbus-gen-2-flip-up-front-sight-handguard-height-ar-15-polymer?cm_vc=ProductFinding

then you need to put the barrel on the upper and measure how long a handguard you want. when your looking for a handguard, a lot of them give the length.

I have never seen anybody mount another gas block on the end of the barrel to mount a sight. that's why you cant find one.

Thanks for the reply. I have a 7" Midwest on the way. I think Ill just try an A2 style clamp on or something. Is it a PITA to get this setup to cycle Properly?

[Xtracrispy]

That's a good Idea! I already ordered the rail its a Midwest 7" I also like the A2 sight. I wasn't looking at this the right way. I think Ill try the A2 style first Im sure I can find someone to ream it out. Thanks again.

Yeah, should be able to get it done. Good luck.