I have enough parts to put a carbine together and wanted some info on the "F" marked front sight base. I believe the F marked front sight base was made for use on flat top uppers on carbines and the standard front sight base can be used on standard carry handle uppers  on carbines -- is this correct?

The F can be used with a1 or a2 uppers, just click the sight post down a couple more notches. Worked for me on an gov a2.

Unless you just have to have a non F on a carry handle upper, it will work.

I have a nice standard A2 upper and was not sure which front sight base was to be used on a carbine. I have both types of bases and didn't want to have a problem sighting the carbine in. Thanks for the quick reply!

I think they're meant for flat tops for sure.

a "F" marked FSB is almost a 1/2 inch taller than a NON "F" mark fsb.. if i remember correctly it measures .415 taller ( don't quote me on that).. a 1/2 inch is .500 you would have to turn your front sight post ALL the way down to use it on a A1 , a A2 upper has a elevation adjustment on the rear sight also.. so it can work on a A2 turn the rear up and the front down and yes it was made for flat top upper with bolt on carry handles.. because of the extra height.. of the flat top and the carry handle..

1/2" (0.500")  

Hmmm no, 0.040"

Wow!

You'uns is way over thinking this.  

For retro builds a non F FSB  is politically correct with a fixed carry handle receiver.  Doesn't mean a F marked won't work fine!  Retro builds are generally anal to the last minute detail and no retro's came with F marked FSB except GM and that was a mold mark and had nothing to do with FSB height.

More than likely either F or non F marked FSB  is going to be fine for fixed or flat top.  If not on a flat top put a .040 taller sight post in it if all you want to do is shoot 10-25 yds and talk about what a tack driver it is or move your head an inch down the stock.  Watch out for ricochets because you probably have a better chance of shooting yourself than not zeroing your weapon.

Build it, headspace it and shoot it!  Won't run? Fix it!  Sure ain't nuclear physics.  Slingshot is probably harder to build and shoot accurately than an AR platform weapon for most.  

Was wondering about this myself...

Follow up question:
If I understand correctly, I can properly use a F fsb barrel and have it sight in, are new carry handle uppers being manufactured?

Sorry to hijack

ps...Also, any links to info detailing differences in A1 A2 ect...?

If I understand correctly, I can properly use a F fsb barrel and have it sight in,

Yes,  even on my flat top upper 16" carbines I can 25 yd zero with less than .020 protruding above flush on FSB using detachable carry handle.  Sight post is approximately .075 measuring thickness at edge. Leaves more than .050 in the hole for stability.  I can't make them wobble.

are new carry handle uppers being manufactured

Yes. NDS (site vendor) does authentic M-16 retro copies and also sells them through Brownells (site vendor)  I believe.  

For other vendors A-1 style only C-7ish is current production with shell deflector.  Various vendors sell Splintered A code stripped  A-1ish uppers but they usually sell out fairly quickly when available.

For A-2,  RRA probably most popular for complete assembled upper but various vendors also offer this option.  Generally Pete at Legal Transfers (site vendor) on EE is least pricey for RRA.  EE = Equipment exchange or top orange button on page.  This you should know with + 63 feedback.  Think Delton is least expensive at $150ish delivered for A-2 currently.  Various other vendors also,  just have to look.

ps...Also, any links to info detailing differences in A1 A2 ect...?

Need to read Colt variations guide at top of this page in retro section and in A-2 section read A-2 variations guide.  Elkie and Augee have pretty much spelled it all out for those who would like to know in fairly accurate chronological order.  For retro also check wwwretroblaclrifle. Great examples of military, foreign and civillian weapons including accessories.  

Basically A-1 = 1 - 12 twist rate and pencil / LW profile with adjustable windage only and A-2 = 1-7 twist rate govt profile barrel or thicker on the end from FSB forward with adjustable elevation and windage.  A-1 FH is open slotted and A-2 is boxed on bottom and requires indexing for no signature in dusty environments.  A-1 sight aperture is dual plane with small holes L marked for long range and A-2 is same plane with one large 0-2 marked  (2=200) and one small hole for long range.  A-1 triangle HG's on rifle and same as A-2 on carbine and A-2 has a more reinforced HG.  A-2 stock is 5 /8 " longer by using stock spacer and longer screw.  Authentic A-2 was burst and A-1 was full auto.  PG has finger rest on A-2 and A-1 doesn't.  Think that's it.

For zero'ing read TM manuals for M-16 - M-16A1 and for M-16A2.  Should be able to find these with simple google search.  Soldiers manual goes more in depth and also can be googled.  Retro member .303enfield was decent enough to provide those interested with copies of M-16 TM a few years back.  Don't know what he still has but they are also available at most funshows or on e-bay and such and it's $5-10 well spent.  Probably the one item that can save lives, body parts and keep an AR running tip top.

A-1 set post 11 clicks down from flush for elevation and adjust from there for individual for desired distance.  There is no more adjustment.  It's all in aperture and  hold over after 350 yds or such even with long range aperture.   Not like many can shoot out there without a target the size of a barn door.  Windage start with aperture  in middle or mechanical zero.  MZ = perfect world and does not account for mfg imperfections or personal eye parallax where one may have to adjust to hit the center of target a few clicks.

A-2 start with post flush with FSB for elevation and aperture in the middle for windage this should be mechanical zero if everything was installed correctly.  FSB, barrel etc and adjust for individual.  

With A-2 windage will need to flip aperture to finite to get at hole for elevation drum set screw to synchronize for individual tastes.  Soldiers manual will explain but USGI wheel / drum is actually two piece and set screw locks them together.  Loosen allen set screw until bottom turns while keeping top constant to make this adjustment.  

Regardless of what one wants out of hobby the whole idea is to have fun in a safe manor without causing bodily injury to one's self or others and don't damage or destroy others property.  When I was a kid I could hunt and had permission to hunt an easy 10 mile radius on foot.  Today due to human's destroying others property,  leaving trash and a mess for land owners to clean up I would be lucky to come up with 200 acres.  This has all happened in past 40 years or so.  

Anyone remember the old Indian paddling his canoe commercial in the polluted lake with tears in his eyes? Usually came on nightly around the same time as the VN body counts.

Great info. Thank you!
The hunt for a stripped A1 upper begins!

Yes, I do, https://www.youtube.com/watch?v=8Suu84khNGY .

During production of 600 series carbines Colt made a carbine specific front sight post that was .040" taller than the rifle front sight post. This was to remedy the occasional zeroing problem encountered on carbines due to the reduced sight radius. This carbine sight post continued to be used on 700 series Colt carbines until the M4. The F marked front sight base was developed in conjunction with military adoption of the M4 Carbine. This did away with the carbine specific front sight post and solved the logistical issue of having two different sight posts in military inventories.