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Posted: 2/1/2014 10:03:00 PM EDT
| Hi, I am working on a non-AR project gun and will be using an AR rail-top, set screw type gas block as a base for the FBUS. That's why I am here on the AR forum for the first time. The gas block will not be connected to any gas system, just used as a perch. it will mount on the non ported portion of the muzzle break. I need help figuring out which height ("receiver rail height") or ("gas block height") gas block to get. Or more correctly, which combination of gas block height and FS height will get me to where I need to be. The RS will sit on a short rear rail that is already on the gun. I plan on using an A2 RS. The top flat of the existing rear rail is 36 or 37 mm above the centerline of the barrel bore. Does either of the 2 available heights of railed gas blocks put the top of the rail section at or near 36-37mm above barrel bore centerline? If so, I can use the shorter style FS that is meant to be mounted on the same plane as the RS. If neither block height gets me close to flush with the rear rail can the difference be "made up" by using either of the 2 possible FS height styles available? Wish I had some of these parts in hand so I could measure them up myself... Thanks in advance for your patience with this long post and for any help you can offer. |
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You will have to be very careful with this (kinda like what you are doing it seems). Most gas blocks on market are below the rail height of the fore-arm/upper.
This is overcome by most people using low profile gas blocks (under) and free float fore-arms. I have put on the cheapie railed gas block that was short then put a folding front sight post that was designed to bring up the front sight post to proper height for the rear sight on upper (got that on amazon) but if you want the minimum amount of weak links you will have to spend a little more. I was able to find both size of front sight units on amazon and both that I used worked on the application I had. They both were clearly labeled. Deal with a name brand company (not e-bay and I would even caution against amazon folks) like; I was going to list a few but that could start several hundred suggestions of what I missed. There are many great companies that are represented here on this forum. There are a couple of blocks out there that will suit your application I just can't name them right now. Maybe this will start the suggestions coming in. |
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