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1/22/2020 12:12:56 PM
Posted: 10/11/2007 11:47:25 AM EST
I have a 14.7 CMMG barrel with the F marked FSB. I mounted it to an A1 upper, but didn't get a chance to shoot it yet. Is this going to be a problem for me? I didn't think about it when I ordered it from CMMG and now I am having second thoughts about the height of the FSB.

Any help would be appreciated.
Link Posted: 10/11/2007 1:21:27 PM EST
Aren't the "F" marked front sight bases taller for use with BUIS on flat-top uppers? It may be too tall for a carry handle upper. Perhaps you could return/exchange it?

Link Posted: 10/12/2007 4:49:24 AM EST
The height is fine.

The original M16 carbines, due to some strangeness of shortening the sight radius requiring a higher FSP were issued with standard FSB's, but front sight posts that were taller.

When big Army started buying M4's in bulk, they decided it was easier to only stock one size front sight post, and just raised the base on carbines, hence the "F" marked FSB.

So an "F" marked FSB should be the right height so long as it has a standard front sight post. Which it should.

HTH,
~Augee
Link Posted: 10/12/2007 5:42:15 AM EST

Originally Posted By Augee:
The height is fine.

The original M16 carbines, due to some strangeness of shortening the sight radius requiring a higher FSP were issued with standard FSB's, but front sight posts that were taller.

When big Army started buying M4's in bulk, they decided it was easier to only stock one size front sight post, and just raised the base on carbines, hence the "F" marked FSB.

So an "F" marked FSB should be the right height so long as it has a standard front sight post. Which it should.

HTH,
~Augee


Thanks for the info. I guess I will fire a few rounds today to see how it sights in.

Link Posted: 10/12/2007 12:33:29 PM EST
I sighted my rifle in today. I had to crank the front sight down a bit, but it isn't bottomed out to get zero. So far so good.
Link Posted: 10/12/2007 3:45:08 PM EST

Originally Posted By K9-Bob:
I have a 14.7 CMMG barrel with the F marked FSB. I mounted it to an A1 upper, but didn't get a chance to shoot it yet. Is this going to be a problem for me? I didn't think about it when I ordered it from CMMG and now I am having second thoughts about the height of the FSB.

Any help would be appreciated.


This is just the info I was looking for. Changed my flattop out for a A1/C7.



Thanks!!
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