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Posted: 1/10/2013 2:56:53 PM EDT
| I'm waiting on parts, so I decided to mess with the upper I managed to acquire just before the panic. I'd like to replace the FSB with either a low profile gas block or a single rail gas block. The thing is, I really like the Magpul handguard that I've installed. Is it possible to replace the FSB with either of these and retain the handguard cap? Any opinions on which (low profile or single rail) to use. I suppose using a single rail would give me a slightly longer sight radius. |
| Many barrels are fitted with railed gas blocks that secure the hand guard end caps. Pick one and make the swap. IMHO, I think you are going about this backwards. Most people want to remove those railed gas blocks and install railed or tube type hand guards that reach out over the barrel a bit further. Like you said, this improves the rifles sight radius. |
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You could cut down the FSB. Won't work if he still wants to use the magpul handguards. As he will have nowhere to mount a front sight. He will need to use a railed gas block. That's what I'm trying to understand. What are your plans for a front sight if you remove what you have and go with your low pro option? |
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Originally I wanted to go with something like this: http://yhm.net/index.php?main_page=product_info&cPath=2_6&products_id=6 . Unfortunately they seemed to be made with the same unobtanium that most other AR parts are made of at the current time. I noticed that I could find both low profile and railed gas blocks in stock. Option 1 would be to buy a railed gas block that has the same height as the receiver rail. Then I could mount a front sight to the top of the gas block. Option 2 would be to use a low profile gas block and mount the sight to the top of the handguard.
Maybe I should just live with seeing the front sight through the optic until the current parts availability issues are over and prices have come down out of the stratosphere. That shouldn't be more than six or eight months. javascript:insertText('  ');
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What I did was get this quad-railed barrel clamp - yeah yeah - a CHEAP part supposedly - but it's on solid and traps the end cap firmly against the handguards. I had to add a little railed riser block to get even with the receiver rail. THEN I had to make grooves in the blocks' "shoulders" with a Dremel tool to allow the "wings" or tabs of the Magpul Mbus folding sight to depress far enough for proper operation. There are also plain barrel clamps tha'd do the same trick. One could get all technical and get one with a set-screw or even add a set-screw and make a tiny divot in the barrel to trap the set-screw. I keep looking - maybe there's a different clamp somewhere with just the one railed "wing" the same height as the Receiver rail.
Just thinking: My original idea was to just add a "receiver-height" railed gas block, obviously non-functioning but acting as a barrel clamp. That would mean removing the flash hider so I went the dedicated clamp route. One more: I left the hider on but as a penalty had to file-out the inner diameter of another end cap to just slide over the hider and down to press against the handguards. Like dominoes falling, I then noticed that the guards (non floating) wobbled about quite a bit since the end cap hole was now larger! Fixed this by happy chance... I had another barrel clamp with rails - this one for a A2 front - and it came with two sets of bushings. These were pairs of curved metal with a thick ringed edge on one end when put together. I used the needed set on the A2 setup - and it turned out that the remaining set was the exact ones for the barrel on the carbine! A little more filing-out of the end cap opening and it went right in, making the barrel immobile. Sometimes you win one... 
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