Yeah, I know there's some info on retro black rifle and elsewhere that touches on this.  What I'm looking for is something like a variation guide on the various sight wheels.  For example, the GM Hydra-Matic is said to have a very distinctive "3" on its sight wheel.  I was just wondering if anyone has done an in depth look at the various sight wheels and tried to put together a timeline and a variation guide.  It sure would be helpful in trying to determine the lineage of some A1 uppers.

I'm interested as well.  I have photos of sight wheels on receivers which I can post if someone would tell me how to post photos.

I'd also be interested in decoding the different types of arrows on the receivers.

Tag for interest.

If you want to email the pics to me I can post them up.

A1 Sight Wheels submitted for comment.

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Thank you for posting those.

I like the font on #21, perhaps only because it is different, or just deeper and clearer.  Does seem to be the casting marks that change the most, really, so this may be msotly an upper-receiver casting design thread instead of a wheel thread.

USGI are forged. Olympic Arms crap was cast.

Sorry, one of my pet peeves.

The other is ordinance (a piece of legislation enacted by a municipal authority) in place of ordnance (artillery, weapons, ammunition, and related equipment).

My apologies.

Lot of variation in the sight arrows too. I'm guessing #41 is a 601 upper with a later sight wheel?

The distinctive flattop  3 with the down-slanted middle appears in 7, 9, 10, 11, 17, 19, 24, 26, 28, 29, 33, 37, 41, 43, 47.  This type of 3 has been associated with the GM Hydra-Matics, but I don't think all of those are from the GMs.  I note the sight arrow on several are open or partially so.  Someone commented in another thread here that these arrows are found on commercial uppers. I really don't know.  If I had to guess, I'd say some but not all of the sight wheels with the flat 3 mentioned above do come from the GMs.

I agree that the distinctive flattop 3 with the down-slanted middle appears in 7, 9, 10, 11, 17, 19, 24, 26, 28, 29, 33, 37, 41, 43, 47.

However, not all of these sight wheels are similar.

For example, sight wheels 41 and 47 are the only two with a straight "1."

Other sight wheels have a small angled "1" (17, 19, 24, 26, 28, 29, 33 and 43) while others have a large angled "1" (7, 9, 10 and 11).

This indicates at least three different versions of the sight wheel with the down-slanted middle, but there may be more versions.

For example, when looking at 7, 9 10 and 11 with the large angled "1", the "4" is different with 9 in that it looks like it has a diamond shape in the middle while the others look like they have a small dot.

Just some food for thought.

Do you know which ones came from Hydra-Matics?  EDIT: Comparing the sight wheel and arrow of a known example here:

https://www.ar15.com/forums/ar-15/My_original_GM_Hydramatic_upper_has_arrived____Now_with_GM_BCG_____Pic_Heavy_/123-572546/

I conclude 7,10,11 and 37 should be GM Hydra-Matics. There may be a few others depending on whether the open arrow is GM also.

I'm not so sure that the arrows are a defining factor for GM uppers.  Shown below are demilled sections of three known GM uppers.  The arrows appear to be different on each upper.





https://www.snapfish.com/photo-gift/share?via=link&token=9ObI13sxJsgdhfUFKXgNeA/SFO/27947732617060/SNAPFISH
https://www.snapfish.com/photo-gift/share?via=link&token=9ObI13sxJsgdhfUFKXgNeA/SFO/27947733075060/SNAPFISH
https://www.snapfish.com/photo-gift/share?via=link&token=9ObI13sxJsgdhfUFKXgNeA/SFO/27947733076060/SNAPFISH

I don't see the open arrow in those 3 pics but there is another thread here on the GMs where they show some Uppers reported to be GMs that have the open sight arrow. I'll look for that link.

Here's the link: https://www.ar15.com/forums/AR-15/GM-or-HandR-upper-assembly-an-old-and-somewhat-confusing-subject-/123-584919/

Probably a dumb question but what is the purpose of the numbers? I have Daniel Defense fixed rear sights on most all my AR's. They also have those numbers but I've never utilized them. I just move to the left or right to set the POI.

The numbers are used to set the initial battle sight zero. Here is the A1 procedure:
"Sight adjustments. If the battlesight zero has not been previously determined, place the M16A1 sights in the starting position.Set the front sight post so that the base of the post is flush with the top of the front sight post well, then go clockwise for 11 clicks.
Center the rear sight aperture within the rear sight housing by moving the rear sight all the way to the left, then moving it 17 clicks to the right.
With the sights in the starting position, fire a three-round shot group. Once a shot group of 4 centimeters or less is achieved, adjust the sights to move the shot group to within the zero circle.
Find the horizontal (right-to-left) line nearest the center of the shot group. Follow the line left or right to the nearest edge of the target. Move your front sight by number of clicks marked on that target line by turning the front sight in the direction of the arrow in the front sight figure nearest the center of the shot group.
Find the vertical (up-and-down) line nearest the center of the shot group. Follow that line to the top or bottom of the target, whichever is nearest. Move the sight by number of clicks marked on that target line by turning the rear sight drum in the direction of the arrow in the rear sight figure nearest the center of the shot group.
Determine the battlesight zero. Determine the 250-meter battlesight zero by firing a series of three-round shot groups at the 25-meter target. Aim at the center mass of the 250-meter scaled silhouette and adjust your sights until the center of this acceptable shot group is within the 4-centimeter circle that appears on the target."

Mine:

I had to turn part of the image to make the '1' appear at the top like all the pictures above have.  Of note - my "2" is seemingly unlike any 2 in the pictures.  My upper is of an unknown make, though - the place I bought it from wrote that it could have been a 'LAR Grizzly' upper receiver, but I don't know and they weren't sure.

Interesting sight arrow. Looks a little like no 36 pic if we assume some wear.

I believe that the photo provided above by Anti_Russian is of a modern upper receiver made by Anchor Harvey.  As such, it is my opinion that there is no correlation with the directional arrow on this receiver and those found on retro receivers.

You are correct.  Mine is a modern one.  I didn't know if this was a study of all A1 wheels, or just ones that were from ... well, what year is the newest this thread is supposed to address?

Production of the A1-series ended in 1982.