Years ago, I placed each of my measuring spouts on a flask filled with Goex FFFG black powder, then weighed each of 10 charges on a scale known to be accurate.
The true weight of each of the 10 charges was added up, then divided by 10. This gave me the average. This average was written on a piece of masking tape that was rolled around each spout's exterior.
With the smaller spouts for pistol, the advertised grain weight wasn't far from the measured weight.
But with larger spouts for rifles, the difference was slightly significant. For example, I learned that my 80 gr. spout -- when measured with Goex FFG black powder (my granulation of choice for my .50-cal Hawken) actually threw a charge of about 74 grs. -- a reduction of 7.5%.
Now, will 6 grains variation make a big difference shot-to-shot? It's probably on the edge of effect, but knowing it existed bothered me. So, I bought a 90 gr. spout and measured and filed it down until I reached the length where it consistently threw about 80 grs.
I needn't have bothered. I should have weighed each charge going into the rifle, found the most accurate load, then created a powder measure based on that.
The most disparity I've found on pistol measures is 2 grains, and that's on a 40 gr. measure. With FFFG powder, it throws about 38 grains.
Considering the rudimentary sights on most of these revolvers, the relatively short barrels (compared to a rifle) and the plinking nature of their use, 2 grains variance would be difficult to spot on target.
Factor in my 58-year-old eyes, the "shakes" because I decided to skip breakfast that morning, the momentary lurch of the planet at the exact moment the lead ball travels down the bore (my favorite alibi) and a host of other impediments, and the issue becomes moot.
As for a "standard" load for the .44s, while U.S. and Confederate regulations may have called for X-amount of powder and bullet weight to be standard, dissection of original paper cartridges shows a great disparity in both weights.
Contractors and government arsenals constructed cartridges based on the recommendations of quality control officer Good E. Nuff.
The Nuff family continues to oversee manufacturing tolerances in government and commercial production facilities to this very day. In fact, the Nuff family of inspectors is worldwide and probably intergalactic.
For your steel-framed Remington .44, I'd suggest you consider 35 grs. of FFFG black powder -- or its equivalent -- as maximum when used with a .454 ball and lubricated felt wad.
Beware of Hodgdon 777! It is NOT designed to be used volume-for-volume against black powder, like Pyrodex P is. I strongly suggest you visit the Hodgdon site and read up on 777 (and Pyrodex P, for that matter) before using them.
You CAN overload a revolver with 777 propellant and create pressures beyond those recommended for the cap and ball revolver. I don't like 777 myself because it's tricky stuff to use. Too much seating pressure on a ball can -- apparently -- raise pressures significantly.
I don't have access to a modern ballistics lab so I can't positively state that pressures are increased when you seat a ball hard on 777, but the recoil is felt to be much greater and I've had more incidents of caps fragmenting.
Lacking a cartridge case to measure, it's difficult or impossible to determine when you reach maximum or greater pressures in a cap and ball revolver. Consequently, I use FFFG black powder or Pyrodex P and know that I can't possibly use more than a well made, modern revolver can handle.
For a starting load, I'd go with 25 grains.
Buy a Lee Powder Measure Kit. It has a good variety of dippers and a slide-rule selector that shows how much powder is thrown with each dipper. The various granulations of black powder and Pyrodex P are included.
Pour the powder into a clean powder can at the range from which to dip the measures. When shooting, snap the plastic top on top of the can and move it behind the shooting area so no sparks may reach it.
But to satisfy curiosity, measure 10 loads on an accurate reloading scale and obtain the average. Then place that average on masking tape rolled around each spout's exterior.
I use the tape and notation because there is much higher variance in my memory than in any spout ever made -- and I don't trust the Good E. Nuff family's scrutiny.
"And lo, did I see an ugly cat. Smoke. Brimstone. Holes in parchment. And this ugly cat was much amused." --- The Prophesies of Gatodamus (1503 - 1566)