Matt Herman said
Hey all, I have what I believe is a Lyman #2 tang sight on an 1894 and am getting it squared away on this rifle.

  

No, a No. 1; the No. 2 had a large eye-cup or disk.  Appears to be in excellent cond., but turned down tight to lowest position.  The fold-down aperture is the part that usually sticks.  Why don’t you just take it off & submerge it in a small container of carb cleaner?

Matt Herman said
 I’m embarrassed to say I didn’t notice the flip down aperture, and I’m still learning a lot.

  

Early Lyman catalog illustrations always show this in the “down” position, because Wm. Lyman strongly promoted use of the larger aperture for hunting.  Before the #2 came along (1898-9), there was no “No. 1”–it was called the Lyman Combination Sight, because (according to Lyman’s patent description) the turn-down ap. was intended to be used for target shooting, the larger ap. for hunting, therefore making it a Combination sight.  Few customers, evidently, paid any attention to these instructions & left the turn-down in the “up” position, which after 100 yrs of neglect, is frequently stuck. 

For decades I’ve been hoping a Lyman box without the “No. 1” marking would show up on ebay; I’d be satisfied with the box alone, without the sight itself.  Boxes marked “No. 1 Combination” show up from time to time, but these were obviously made after the #2 had gone into production.

oldcrankyyankee said
Clarence, are you telling us that the round eyelet acting as a pivot is another aperture for this sight? 

  

Exactly, two sizes.

oldcrankyyankee said  Can you tell me how to swap them over? rather have some guidance so I dont ruin mine 

Like I said, it may be stuck tight against the larger ap by old dried oil or corrosion, so using a punch slightly smaller than the large ap, force it backwards, i.e., towards the muzzle.  Wouldn’t hurt to soak it in carb cleaner first, but it may come free by pushing alone.

Chuck said
 If you wrap a rag around the barrel you can carefully grab it with some smooth jawed pliers.

  

Use a strip of leather & you won’t need the smooth jawed pliers–I’ve done it many times.  Smooth jawed pliers generally have parallel jaws, which don’t grip as well as the curved jaws of regular pliers.  WD 40 is not the best solvent, if dried oil is why it’s sticking.  Better than carb cleaner for dissolving any kind of petroleum product is lacquer thinner, which won’t harm a blued finish.

Matt Herman said

I have some paint thinner and also VM&P Naptha here, no lacquer thinner. Ok to use either of those? Pretty paranoid about harming the finish so if I need to run grab lacquer thinner I will 

Sure, I’ve never heard of a petroleum-based solvent that would harm the blue, but LT will even soften dried epoxy.  By the way, rotate the barrel clockwise to raise the stem. 

Matt Herman said
 

I know that we know the patent date as it is stamped on the sight, but is there a particular date range in which they were made? And at what point did the next variation come along?
 

  

Persistence rewarded!  (I was next going to recommend application of a Stilson.)

At some point late in production, precise date unknown to me, the Lyman name-marking was moved to the top of the base in large letters, but no other changes were made in the #1 & #2.  In 1905, two new models were introduced, 1A & 2A, which differed from the originals in being fitted with a locking lever in place of the spring-bolt–a blatant sales-gimmick if ever there was one, which did nothing to improve the sight.

I don’t know when they went out of production, but all models are still listed in the 1959 Shooter’s Bible, the first one I ever bought.  Probably wasn’t much longer after that they started becoming “collector’s items.”