M1 Rear Sight Variations

[reconbob]

    For the longest time I thought the quick way to identify a new manufacture fixed rear M1 sight was to look for the checkering or hatching around the rear sight hole to reduce glare. I saw a sight on GB that looked all original and correct - except no hatching - so I got it to examine. Now, the only source I know of for new manufacture/fake M1 sights are the ones they made to put in the "Russian" M1928A1 kits so they could sell the Lyman 55B sight as an "extra". The "Russian" fixed sight is easily recognized because the fake LYMAN stamp is the wrong size - maybe twice as big as original. The sight I just got is correct in every way, and i would say it is original, but there is no hatching around the sight hole.

Here are 4 sights - On the left fake "Russian" sight, next original with no hatching, next original with hatching, and on the right older sight with the full LYMAN address. This sight has the hatching, but it is so faint that you can only see it viewed with a magnifying glass.

Here are the apertures. On left, old sight with Middlefield address and barely visible hatching.

On the right, original with no hatching

On left original sight with hatching. On right "Russian" sight with no hatching.

I would say that the presence or absence of the hatching is not the last word. It could have no hatching and be correct. The "giveaway" for the fake sight is the oversized LYMAN stamp.

Bob

[Merry Ploughboy]

Hatching deleted as a cost reduction?

[dalbert]

Could have been missed?  Or maybe cost reduction, as Merry Ploughboy suggests.

David

[Bridgeport28A1]

The plain L rear sight originated on the later production 1928A1 models and carried over to early M1 model Thompsons.

[TSMGguy]

Looks like maybe the rivet holes are countersunk from the top on the originals?

[Merry Ploughboy]

1 hour ago, Bridgeport28A1 said:

The plain L rear sight originated on the later production 1928A1 models and carried over to early M1 model Thompsons.

So, rather than being deleted, the cross-hatching was added, perhaps to address something such as a glare issue noted by users of the earlier, flat rear surface sights.

[Bridgeport28A1]

5 hours ago, Merry Ploughboy said:

So, rather than being deleted, the cross-hatching was added, perhaps to address something such as a glare issue noted by users of the earlier, flat rear surface sights.

ReconBob has the Middlefield address L sight as having cross hatching in the second photo. It is thought the Lyman sights with the Middlefield address is the first version of the plain L sight. If that is correct the lack of cross hatching on an original L sight is either a missed manufacturing step or an elimination as mentioned in a previous post. 

Edited November 9, 2025 by Bridgeport28A1
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