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10/23/2010 3:50:48 PM EDT
I know, I know... yes I've looked at all the docs, but I still don't know exactly what I have here. The one on the left is an early one with no drain hole. Neither have any discernible markings that I can see.  




TIA !
10/23/2010 3:55:48 PM EDT
[#1]
if a penny fits in the hole for the barrel it's a .750, if it's not even close to fitting it's a .625
10/23/2010 3:57:51 PM EDT
[#2]
Both are ..625.
10/23/2010 4:02:37 PM EDT
[#3]
I took ID as inside diameter

what else do you want to know?
10/23/2010 4:08:57 PM EDT
[#4]
Quoted:
I took ID as inside diameter





Cast, forged? How come no codes?

Oh, yeah, and did John Wayne use one in TGB?  

Seriously, thanx!
10/23/2010 4:13:17 PM EDT
[#5]
from the guide at the top of the page;

The cast front sight base was replaced by a forged part for obvious reasons. The first version of the forged front sight base was machined smooth to remove forging flash and used on M16 and XM16E1 rifles, and on the M16A1 for a time. Production started as early as 1964, and was used as late as 1969 and serial number 1,750,XXX. A bottom drain hole for the front sight post assy was added in 1967:


yours are forged
10/23/2010 4:37:54 PM EDT
[#6]
CC,

Thanx for the info!  

I can now build a retro 604 like the one I used and a 603 (M16A1) for a friend.

... and then a...and then...
10/23/2010 4:42:44 PM EDT
[#7]
anyone got any ideas what "the obvious reasons " were? weak?hard to make? ugly?don't work?
not very obvious to me.
10/23/2010 4:46:45 PM EDT
[#8]
Quoted:
anyone got any ideas what "the obvious reasons " were? weak?hard to make? ugly?don't work?
not very obvious to me.

They're everything but ugly.
10/23/2010 4:48:30 PM EDT
[#9]
Quoted:
anyone got any ideas what "the obvious reasons " were? weak?hard to make? ugly?don't work?
not very obvious to me.


Forged was stronger than cast
10/24/2010 12:51:54 PM EDT
[#10]
OP, do they have a  raised (vs engraved) arrrow, and "up"?
if so they are probably early Colt.
10/24/2010 1:05:22 PM EDT
[#11]
They look forged to me, by looking at the bottom left picture you can see were the HG retainer sat. Cast FSB would sit level with the top of the HG retainer, while forged sat higher than the HG retainer.

The letters would be engraved on these hotdog250j.
10/24/2010 1:25:26 PM EDT
[#12]
hk has a good visual point.. the bottom of the rear leg on a forged fsb is semi-circular and higher whereas a cast fsb is flat and a bit lower compared to the top of the handguard cap

forged


cast
10/24/2010 1:42:26 PM EDT
[#13]
Quoted:
hk has a good visual point.. the bottom of the rear leg on a forged fsb is semi-circular and higher whereas a cast fsb is flat and a bit lower compared to the top of the handguard cap

forged
http://img.photobucket.com/albums/0603/Ekie12091941/variation%20guide/MPC11.jpg

cast
http://img.photobucket.com/albums/0603/Ekie12091941/variation%20guide/fsbarmalite.jpg


Good point crackedcornish. I never noticed the flat vs rounded on the FSB's, just that they were either flush with the HG cap or higher.
10/24/2010 2:18:05 PM EDT
[#14]
Nice 'catch', cc! That sure helps...
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