Marlinman is going to be more definitive so if he overrides my 2 cents, it's worth more!
As for a tang sight that fits the 1881, I'm not so sure. I don't have an 1881 but I've seen tang sights on them. If it's drilled and tapped and it has the standard 1 and1/8 spacing for later marlins, any of the M prefix Marbles sights will fit but the collar (especially M3 designed for the 22 levers) may be too short and to use the sight the stem would always have to be extended.
With Lyman your best bet may be J, JA or JM which where all designed for the large frame Marlins J & JA for the 1893's and JM for the 1895.
Personally, I would go with a vanier tang sight. On an early 1881 it may be more authentic. Also, with the money you get from the Lyman 21, you can get a good vanier tang sight.
Axtel has a nice selection of new Vanier Tang Sights. Finding an original antique vanier tang may be dificult and expensive.
The Lyman tang sight for the model 1881 is marked "M". This is a very rare sight, and the last time I even saw one, it was well worn, with no finish left, and the seller offered it to me for $250! A bargain price I suppose, but I had to pass.
The Lyman 21 is a desireable sight, if the gun you own has the correct extra holes already in it, and it needs one to fill the holes. Lyman did make these styke sights to fit Marlins, but I'm not sure about the 1881. I know I've seen a few 1893's sporting them, and one 1895 too.
IN Old Gun Sights a Collectors Guide, 1850-1965 It indicates that Marlin Model 1881 Repeating Rifles, manufacturec 1881-1892 could have as optional rear sights:
Marlin Sporting Leaf Rear Sight,
Marlin Gallery Peep Sight,
Marlin IMproved Graduated (tang) Peep Sight,
Marlin Improved Vernier Mid-Range (tang) Peep Sight,
Marlin Improved Vernier Long-Range (tang) Peep Sight,
Lyman No 1 Combination Tang Sight, or a
Lyman No 2. Tang Sight.
It also shows the same sights were available as an option on the 1888 Rilfe, 1889 Rifle, 1889 Carbine, the 1891 Rifle, and the 1892 Rifle.
mm93 is right as usual; i have a lyman tang on my 1881 [picked up the sight years ago, hoping i'd get another 1881, and did]; it sure works great and helps me lay the shots right in at 100 yds. [using 405 gr. cast and hodgson 777]. sure helps my old eyes enjoy the gun! [think i paid about 50-60 bucks for the sight some years back]
i didn't realize it at the time. it is mostly brownish but so is the color of the 1881 i have; the gun has almost fiddleback wood, somewhat dark, but i beleive it's the original finish; the metal is smooth but brownish; the bore very good ++ and the gun is smooth and accurate....it is really one of my favorite guns. the first lever action i ever personally owned [not borrowed] was an 1881 also a 45/70; got it in 1981; it looked like it had been stored in a barn: brown finish and the action wouldn't cycle, being gummed up with hard grease and pieces of hay! i cleaned it up and the bore was fairly good and it shot very well; the lever droooped; i sold it to a friend after 10 years or so, and was confident i would soon get another, but it was probably ten more years before i did; i have long been accumulating various sights, esp. tang sights, and also nifty front and rear special order sights; i enjoy 'trciking' out my favorite shooters with them.
That droopy lever on a model 1881 is an easy fix! Either tighten the screw in front of the trigger guard, which holds the lever spring, or repalce the lever spring! I make them from .059" piano wire, if I can't find a replacement.
thanks, that's good to know! the 1881 i have now is really tight; they sure are fun guns; i have an 1878 Burgess 45/70 also, and although it shoots well, it doesn't have the smoothness of the 1881; i'd like to have one of the 1881 lightweights in 38/55, also. they are hard to find too.
Cable, Thanks for the info. Mine is a light weight 38-55 and one of these days I want one of the heavier ones. They are a blast to own as I take mine to the range and people always stop and ask what it is. Moodyholler
Yes, the small frame 1881, which is often confused with a "lightweight" 1881, are much scarcer than large frames! Of the two small frames, I see them in .38-55 much more than .32-40! I'm still on the lookout for a small frame .32-40 in decent shape! I've got the other sizes and calibers, but the .32-40 has eluded me! Brophy says there were less than 3,600 in .38-55, but less than 1,800 in .32-40! So compared to the .40-60's at @6,200 and .45-70's at @4,600, the small frames are tough finds!