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Discussion Starter · #1 · (Edited)
I have a RRA lightweight upper, I added a Troy BUIS set to the railed gas block. Went to the range yesterday to sight them in and after seeing it shoot almost 2' high at 25yds I realize something is wrong... :hmmmm: Obviously it's a low-profile gas block and I'll need to replace it, the problem is I don't know what I'm looking at as a replacement.

I've found two likely candidates, someone help me out here so I get the correct one.

EGW block... (which looks like the same height as my current gas block...)

MI gas block... (which claims it's 'upper height gas block' for the M4 flattop receiver.

Current setup... I measured the barrel mount, it is .750" I'm assuming it's a clamp-on, not pinned?

And I'm not married to Midway as a source... I just use them to go shopping. I would prefer a clamp-on, the MI is pinned.

 

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that gas block does look low i have one on my Anderson mfg that is the same height as my flat top upper that's what i would recommend
 

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You have 3 options... You can get a taller "rail-height" gas block (as you already mentioned), or get a taller front sight designed specifically for gas blocks, or get a combination front sight gas block.

Changing the gas block is likely the cheapest route. If you want to use your existing front sight, the MI gas block that you linked to will work, but not the EGW.

Simply changing the front sight would be the easiest solution, though a little more costly. You wouldn't have to remove the muzzle device, then the gas block, then the gas tube from the block, before reassembling again. Simply get a taller sight. Troy, MI, and others offer sights that would be correct height for gas blocks.

A combination front sight / gas block would also solve the problem, but would be neither the cheapest nor the easiest solution.


Note: The gas block that you have now (in the pic), is considered a clamp-on. The MI that you linked to is considered a set screw type. Neither would be considered pinned.
 

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Discussion Starter · #4 ·
You have 3 options... You can get a taller "rail-height" gas block (as you already mentioned), or get a taller front sight designed specifically for gas blocks, or get a combination front sight gas block.

Changing the gas block is likely the cheapest route. If you want to use your existing front sight, the MI gas block that you linked to will work, but not the EGW.

Simply changing the front sight would be the easiest solution, though a little more costly. You wouldn't have to remove the muzzle device, then the gas block, then the gas tube from the block, before reassembling again. Simply get a taller sight. Troy, MI, and others offer sights that would be correct height for gas blocks.

A combination front sight / gas block would also solve the problem, but would be neither the cheapest nor the easiest solution.


Note: The gas block that you have now (in the pic), is considered a clamp-on. The MI that you linked to is considered a set screw type. Neither would be considered pinned.
AH! I didn't know that. They aren't very descriptive in their descriptions, and that's not just Midway, but everyone.

I actually ordered a different gas block... The PRI. To be honest, I hadn't thought about having to pull the flash hider off...

I did try a 1/2" riser, it shot 1' low at 25yds. Hopefully I'll get it right with the PRI.
 

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Discussion Starter · #5 ·
Update:

The PRI gas lock appears to be the correct height. I pulled the old one off and test-fitted it... my old Bushnell HoloSight co-witnesses with the sights perfectly.

Not ever having done anything like this before, I had to pony up some loot and get a proper set of roll pin punches and a starter punch. Do it right, I always say...
 
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