Posted: 3/4/2011 4:17:41 AM EDT
| I am currently building a Black Hawk Down Clone type rifle. I started with a Colt 6520 and just wanted to swap barrels. I traded off the LTW Profile barrel and going to buy a 14.5" 6921 barrel. Can I use that FSB with an A2 Upper, or do I need to swap out the FSB to non F-Marked FSB due to the height. (Not sure what the correct nomenclature is for the non F-Marked FSB.) Anyway, any help would be greatly appreciated... |
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To be technically correct for an RO723 or 727 you would need a non-"F"-marked FSB. However, a 6921 barrel is not correct anyways, as the 7xx series notched barrel was of a slightly different profile than the 6921/RO920 barrel.
For practical purposes however, a 6921 barrel assembly with an "F"-marked FSB will work fine. ~Augee |
| Sounds good, don't need to be an exact replica.. Maybe I should have chosen a better discription. Just wanted to make sure that the F-marked FSB would work fine for propper zeroing purposes. I really wanted a KISS type rifle and these appealed to me the most, and I happen to really like Colts.. Anyway, thanks for the input Augee... Really appreciated. |
| So, my best bet would be to put the rifle together, and just attempt to get a good zero and go from there. If in the event that it is not the propper height, I was loking around and found a factory Colt AR15/M16A1 Front sight base. Would this be the part that I need for the correct FSB height? |
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Quoted:
So, my best bet would be to put the rifle together, and just attempt to get a good zero and go from there. If in the event that it is not the propper height, I was loking around and found a factory Colt AR15/M16A1 Front sight base. Would this be the part that I need for the correct FSB height? Correct. If it doesn't work, then proceed to make modifications to the sight post. Front sight base taper pin holes are unique to each barrel, so they're not interchangeable. The only way to make that work would be to buy an undrilled FSB and have it pinned to your barrel, which will be expensive. |
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you can buy front dights that are different hights. you dont need to file anything. just spend 11 buvks on a few differnt heights
if you wanted a KISS rifle why not keep the LT barrel? unless you have a M203 the m4 barrel sure doesnt offer anything for a kiss rifle. that barrel you let go seems to be the most desirable now a days |
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Doubt you will have a sighting problem. Colt carbines prior to the "F"-marked FSB shipped with .04 taller front sight posts.
The "F"-marked FSB eliminated the need to have two different front sight post parts and simplify an armorer's bench stock as the FSB is considered a part of the barrel anyways. ~Augee |
| Yeah, it looks that way huh.. that LW profile barrel is all the rage.. As for rifle, I am just waiting on the NFA stamo to come back so that I can put it together for once. As for barrels, I now have a Colt SOCOM profile barrel sitting in the safe with no real home. I will be putting her up for sale here soon I think. All my previous concerns have been answered, and I will come back with a range report if I have any problems for further advice. Thanks for all your help guys. Much appreciated. |