Lyman 66 LA versus 66MC

[W.R.Buchanan]

I have a 66LA on my Marlin 39AS right now. Someone brought to my attention that the correct sight was the 66MC but wondered what the difference in the two sights is.

It appears that the difference is in the bridge of the sight of which the 66LA being designed for a wider receiver has a noticeably wider bridge.

I didn't think there was any difference however a closer look revealed that that might be the case since the 66LA bridge on the 39AS does appear a little too long for the gun.

Here's pics of my sight mounted to my 39AS. If someone else has a 66MC on their gun, posting a pic would put an end to the debate.

Randy

[pietro]

.

No pic, but receiver peep sights made for for Marlin 39a's have a horizontal bridge that doesn't hang out over the RH side of the receiver wall.


.

[JeffWarner]

I took a couple of similar shots of a Lyman 66MC on a 39a Mountie. It looks very similar to how your 66LA fits, with the exception that the "horizontal bridge" appears shorter (when looking down the barrel, mine is 1.2" from the left edge of the bridge to the end where the windage knob attaches). The Marlin 336's receiver is ~1.0" wide vs the 39a's being about 0.8" wide, so the 66LA probably overhangs an extra 0.2". Interestingly, the adjustable windage scale (the metal tab with the marks) is still pretty far over. I can understand why its not centered when using a 66LA on a 39a, but for a sight made for the 39a ... I would have expected it to line up better.

Randy, can you check a few measurements on your 66LA for me? I've got a vintage Steel 66MC with a buggard base. The bridge (which is also stamped 66MC) is still good and I'm curious if I can use a steel 66LA base with my arm. From the pics, the bases and arms on the 66LA and 66MC look similar and both sights use the same mount hole spacing.

Measurements off my sight. I'm trying to be certain the base is the same and bridge will slide in to the slots machined into the base with no issues.

Base thickness - 0.375" (widest part)
Base thickness - 0.312" (measured from the bridge channel to side of rifle reciver)
Base Width - 1.052"
Base Height - 0.862"

Bridge - Measurements taken along the portion that slots into the base
Bridge width - 0.623" (widest part, its got narrower "rabbet" cuts along the sides of the bridge to fit in groves/slots of the base)
Bridge width - 0.561" (width end to end across the rabbet cuts).
Bridge Thickness - 0.128"


954469544595447

[W.R.Buchanan]

OK Jeff: all of the measurements you took are nearly identical to mine +/- .003.

The 66LA bridge is 1.350 wide in total. I'd bet the MC bridge is 1.150 ish?

I think this is the only difference. Although mine has different knobs.

Randy

[JeffWarner]

OK Jeff: all of the measurements you took are nearly identical to mine +/- .003.

The 66LA bridge is 1.350 wide in total. I'd bet the MC bridge is 1.150 ish?

Randy

Thank you sir, it helps!

I get a bit wider than 1.15" across the MC bridge...closer to 1.25" (outside edge to outside edge). My target Knobs looks more "svelte", but the LA bridge is not that much wider. Its definitely use-able on a 39a.

Jeff