hey guys,
I know there's been several threads about these barrels and marking variations but never really definitive answers about production dates.
from my understanding there is 3 Generations of barrels that are FN for either the A2 or A4 platform

the first Gen is FNMI marked with no date on the barrel,
the FNMI is marked differently and the bottom of the 5's are curved weirdly
along with a weird marking at the the beggining of the barrel.
I have one that came in the box thats dated 1989

Dates known so far for 1st gen FNMI barrels
-05/89

I've only seen about 4 pictures of the box these barrels came in and all had the same date including mine.
ive read before that these were replacement barrels for usgi colt A2's

here are some pictures of the barrel and markings (not mine just random photos ive gathered from the internet )





heres a picture of the marking on the side of the barrel chamber side.
ive tried looking everywhere and no one seems to know what the symbol is or who it came from
could be a proof mark or manufacture etc.



the second generation are also marked FNMI but are dated and roll mark font is different.
earliest barrel ive seen pictures of or info on is dated 2003

Dates known
02/00
01/01
07/05




than there is the 3rd and current generation of FN barrels for the A4 which are the 3s679 cage coded ones that are also dated.

dates known
09/09
2010
2011
07/12
12/12





As far as FN M16A2 upper receivers go there is several variations of them over the years. If someone can help with the timeline on them as far as what years they were produced from and what barrels would of been seen on each one I would appreciate it. I know there would be mix matched specials as stuff got worn out or replaced but would be cool to know what upper/barrel matches came factory.

UPPERS:

Early FK marked ones. (note bushmasters also used the same FK forgings for a while typically FAT FK side to side not staggered forge marks but there is a photo of what seems to be a fat FK upper in the wild )

Thin FK staggered raised


Thin FK staggered raised also but the K is slightly different


Think FK side to side raised


FK stamped both the F and the K


FAT FK marked type's



Than we go on to seeing the next type. As far as I know there's only one variation of this type.
F MB  all letters are raised


next up are all the stamped ones.

F stamped cerro forged. from the looks of it, stampings are not typically on the same spot and some seem to be anodized black others different shades of grey



F stamped Brass aluminum AKA SQUARE forge



F stamped raised M


F stamped splintered A


FM both F and M are raised


Those are all the variations of FN M16A2 uppers ive seen. if you have any others or even better HD pictures please share them that way I can update this as we go with better photos. Also any knowledge on them on what years they came out in or what uppers should be mated to certain barrels for period correct clones.

so basically what I'm trying to get out of this is information on
what years the first gen barrels were produced ?
what years the second gen barrels were produced ?
and what years the 3rd gen barrels were produced in.?

if anybody has a FN A2 or A4 barrel and could provide barrel dates I would appreciate it
that way I can catalog it all and have some sort of Log on here.
the ones that seem to be more rare or harder to track down information are the 1st gen barrels since they are from the 80's
ive seen several online that pop up here and there NIB and all seem to be marked 89

I also have been trying to put together a similar thing with FN A2 upper recievers
how they are marked, anodizing color variations and what dates they were from and what barrels would go with each one
a lot of these older threads seem to be outdated and photos have broken links due to being from photo bucket or other image servers that are no longer supported.
seems to me these types of threads as repetitive and annoying it must be for some people are necessary to be updated and refreshed every couple of years as not everyone knows all of this information and kind of sucks that a lot of the information gets wiped out due to closed threads or broken links.

if people are interested in this topic and think its good for the community as a whole im willing to make some sort of MASTER FN M16A2 M16A4
thread with every variation of uppers, and barrels along with pictures and dates of course with everyone else knowledge though and input since I am not a expert in these just someone who likes to gather information and share it so people can know what's what and how they should look or can look like.

Tag for later

https://www.ar15.com/forums/ar-15/FNMI-A2-Barrel-variations-/127-757126/

Where's the date marking - near the FSB like Colts? I bought a complete FN M16A2 kit a while ago and never looked for a date or any other markings, but I can pull the hand guards off and take a look sometime.

Here's the barrel stamp.

hey, if its dated which im sure yours is
it should be right behind the front sight block on top.
you will have to remove the hand guard or top of the handguard if your using a 2 piece.
and thank you for the info ahead of time.

I tried to get a picture but it's just about impossible as it's under the gas tube. The date looks like 01/01.

sweet! that's actually cool and a good date as far as tracking down when these were made
im trying to go through all the pictures I have of other ones ive seen to take note of the years and markings

Tag for later, off to a VTC.  Got pics of FN uppers that were in the shop back in 16' on personal laptop.

FN M16A2 barrel in shop (off a A2 rifle)
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12/12 dated
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Non F FSB for fixed A2 sights
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Rifle ramped barrel extension
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Thanks for the link.  Reminded me send a text to MauserMatt.  We worked together in Astan.

Got side tracked.  All FN uppers, A2, A4 both rifle ramp receivers and 2 M4/M4A1 uppers, carbine ramped.
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FN M16A2 upper build (upper, barrel, Bolt and Bolt Carrier all FN)  Didn't get close ups of barrel markings.
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A2 and A4 upper with correct A2/A4 bbls. (Non F and F marked FSB, rifle ramped)
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here's 2 pictures of my cage coded barrel I have on my A4

cage code roll mark


and heres the date 7/12


and heres the 1st gen FNMI marked barrel

FNMI roll marking


no date behind the FSB


also have that unknown marking others have talked about previously, could be a proof mark? manufacturer?
no clue, ive tried looking everywhere but have yet to find anything on it. it also has a number 4 stamped on the top side which also have been noted on these barrels. I believe I even saw one with a 3 marked on it.

those raised F marked  uppers are very interesting, haven't see that type.
Ive usually only seen stamped F keyhole and F square forged ones. as far as F mark goes.
cage coded ive seen different variations also

Here are my two. (Crappy quick pictures)

Dated 02/00 I don’t see anything near the chamber.
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Dated ??/09 Looks like an incomplete 6 near the chamber.
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thanks for the contribution, ive added one of your barrel dates to the list as the other one had the same year that was already listed.