I have been informed that shooting 45 Colt black powder ammunition in lever action rifles allows more residue to enter actions because of its brass being thicker/tougher around case mouths compared with 44-40 brass. 45 Colt brass does not seal chambers as effectively at black powder pressures as more flexible 44-40 brass.

Shooting 45 Colt with Starline brass and Goex FFg, as best you can, please identify the rifle lever action - among Marlin 1894, Rossi 1892 Winchester reproduction, and Uberti 1873 Winchester reproduction - that is easiest and/or most straightforward to clean-maintain. My black powder experience has been muzzleloaders and Shiloh Sharps 1863s. Comparatively, these have fewer parts, no feed or extraction mechanics - in essence, not many places into which black powder residue can squirm.

The 45 Colt was never designed to be fired from a rifle; in fact the rims on early ammo is so small that it is barely there. Anyway, nowadays, with thick Starline brass, it won't obturate and seal the chamber and gas comes back all around them; makes the brass dirty too. The Marlin will be the easiest to clean, mostly because it is the easiest to take apart. . The 92 will also be very easy, maybe easier; get which ever one you want. Even the 73/66s; those aren't bad either and are real black powder guns anyway. They won't be hard to clean. I would get the 66, in fact, I did.
And I shoot only black powder in my 45-60 and 50-95 1876s too; no issues. Hell, get the one you want, but for true black powder cowboy shooting, it is the 73 or 66 all the way.

If you are going to shoot black in a lever gun, you will have to use heavy loads to get a good seal in 45 Colt, ie, expansion of the casemouth. That is the reason many like the 44-40. A bottleneck case will seal better and many say the neck is thinner on a 44-40.
I shoot Cowboy Action with black powder and I shoot 44-40 for black and 44 magnum for smokeless. My rifle rack for this includes a Marlin 1894, a Uberti 1866 and a Winchester 92.
In ease of take down and cleaning; Marlin 1894, Uberti 1866 and Winchester 92.
The screws on the sideplates of the 1866 are small and it is a bit difficult to line everything up in reassembly. The 92 has many small parts and is by far the most difficult. The marlin is easy!

Tthe 66 has the side plates that are dovetailed and tightly fitted into the frame, and although they are not hard to remove, they are not nearly as easy as the 73; they fall off after removing one screw.
The necks on Starline 44-40 are probably half as thick as their 45 Colts. I use lots of both. I can measure them if you really want to know the actual thickness.

I have a Turnbull 1886 chambered in 50-110 WCF that uses tough Starline brass, I fire 112 grs of KIK 2F under a 680 gr flat nosed grease groove bullet.

Have never to date noticed and residue blown back and down into the action works, I open the action and turn the rifle 180 degrees to clean, a good wiping stick and patch push the fouling out of the barrel and onto the ground when wiped in this manner.

I have a Smith Enterprises rear sight and can ring a 16" steel gong from 200 yards with hunting confidence building regularity.

That is because your brass is obturating and sealing the chamber. The Starline 45 Colt brass is too thick to do that with BP pressured loads.

10-4, I wondered if the BP loads can be pumped up enough for a good seal, I shoot 35 grs 3F under a 270 gr cast bullet in my 45 Colt SAA, the cases aren't to terribly dirty, and have never had the revolver cease up to 24/30 loads or so before I completed shooting.

Of those you mention the Marlin is the easiest to disassemble and clean.

I have my granddads old mod. 92 Win. 38-40 serial number 158...I have always shot Rem brass, but of late been thinking or ordering some starline as Rem and WW 38-40 is hard to come by and its very thin..

Is the Starline Ok for a rifle? I have been told the brass is thinker and better?? this thread makes me wonder. Also would I need to load hotter.

I've been loading starline .38/40 for my uberti 66 for over two years now, not a hiccup. The only fouling in the action is from the primer

I shoot exclusively 38-40 in a 92, and two SAAs. Whilst Rem, Win, and even Starline 38-40 brass is hard to get; Starline Forty Four Forty is easy to get. I use that.
You won't know the difference.
Yes, Starline brass is much thicker than any other, which is why the OP has all the blowback. Remember, the 45 Colt was never chambered in a rifle, way back then.

If starline 38-40 is thicker brass than the others, I would hate to see those. I use Starline exclusively in my Marlin 1894. Works great. Perfectly even. Getting brass to seal with a blackpowder load is pretty much unavoidable. It is going to happen, no matter what.

You would hate to see those what? If you mean 44-40s necked down to 38, then hate no more; it is the same neck thickness. 44-40 Starline brass is about 1000 times easier to find. I think they use the same drawn blanks for both.

Always thought the .38-40 would be about optimum for shooting with BP in terms of sealing the chamber. It's a capable cartridge, too.

How about annealing the brass before its first use? Will that help?
I use all sorts of 45LC brass and just figured it's going to get dirty - not in a rifle though.