Can I use the same powder, bullets, primers, and casings to load these 3?

I have an 8" S&W 629 I want to target shoot. Mag is too much on the palm to shoot all day, Thinking of loading few hundred .44 Russian to get familiar with my gun

I have a four inch 629 & I load a 240 grain powder coated bullet to 1000 fps for fun shooting. the same load goes 1400 fps out of my Rossi lever gun.
its fun to shoot, not boring not painful.  I use HS-6
I have never loaded .44 Russian & I don`t need .44 special, so I`m not much help.

A great load for 44 spl is  240/220/200 grain lead bullet on top of 7.5 grains of Unique powder with a standard primer. You can go a little lighter if you like. At 7.5 gr it is about 800-850 FPS.  Shoot it all day, yet still lethal. Similar to 45acp or 45LC loads. Look at one of the loading manuals for 44 Rus. 6.5. Of Unique or 4.5 gr of Bullseye should be good.

.44 Russian is nice because the short case will completely eject , no hang ups .

But neither of them is going to impress you .

I woul find ...cowboy .44 mags. .... they are loaded light and you will have brass to reload , if you do reloading .

What do you mean by cowboy .44 mags?

cowboy loads are using powders designed to mimic old west performance in cartridges. the FPS of the bullet is WAY slower than modern powders and pressure is way lower too. some are even deliberately smokey so you get to take cover as you shoot.  

I have heard of several issues with light loads in large cases, first is inconsistent ignition you might get some squibish loads, or just large varation in FPS(i guess there are various fillers that are useful for countering this). second is issue called flash over or detonation using super light charges in large cases where the powder ALL ignights at once instead of progressively resulting in a MUCH higher pressure than expevted, in a .44 magnum oyu ought to be ok but in an older manufacture .44 special it could be an issue.

http://www.reloadammo.com/liteload.htm

.44 mag loads for "Cowboy Action Shooting"

Basically gun games in Western Costumes...

The loads are for timed strings of speed of shooting, so very very light loads.

Do I use the same kind of powder, just different amounts when reloading the three cartridges?

I like this because it consolidates my brass needs to one casing. What is the difference between loading 44 magnum to special/Russian specs and 44 special special/Russian themselves? Just the casing length?

Typically lighter loads will be loaded with relatively small amounts of faster powders like Bullseye, Unique, AA#2.  The heavy loads will use larger amounts of slower powders such as H110, W296, and 2400.  Light loads of slower powders typically don't perform very well and heavy loads of fast powders quickly go over pressure.  The beauty is you can load light loads in the .44 mag case if you desire so you don't need to source the other brass.  All you need is a different powder and a switch from magnum primers used with the slow powders to a standard primer.

Technically there will be a slight change in the powder required due to the different case volumes but the final results will be for all practical purposes the same.  Sounds like you need to buy a reloading manual.  I like the Hornady manuals for this type of study due to the way they lay out the different velocities with different powder charges.

For example:

Using A .44 magnum case a 240gr lead bullet uses 5.1 gr Bullseye to get 800fps for a .44 Russian load.  Then you can use a 240 jacketed bullet and 24.8 gr of H110 to get 1400fps for a stout .44 magnum load.

Using a .44 special case the 800fps load requires 5.5 gr of Bullseye.  Now you will say, "Wait I thought the special case was supposed to take less powder for the same velocity?"  The key here is the .44 special test barrel is only 3 inches long while the .44 magnum test barrel is 7.5 inches.  There's the likely source of the discrepancy in the data.

6.5gr Win231/HP38 & a 240gr SWC makes a very mild very accurate 44 mag load.

no need to use anything but 44 mag brass.

10gr unique or 9.0gr universal makes a great warm load that's enough for deer hunting, but doesn't beat you to death.

.

I suggest you stay with 44 mag brass and pick different types of bullets for the different loads you choose to hand load.  240 gr hollowpoints might be your hunting load.  semi wadcutters your target light loaded practice ammo. You vary the recoil by selecting the powder and weight of the charge once you lock in to a couple of loads you like be consistent.  With 44 Mag I tend to load 2400 or Unique powder.  I see no point in trying to find 44 Russian brass. If you want to light load some 44 special just stay within the recommended powder charges in the loading manual.  Straight walled cartridges are often very tollerant of a variety of  powders which is good because you may have difficulty finding some powders currently. Make notes in your reloading manual so you know what you did last time.  Consistency is a must if you want accuracy.

Get a pound of Trailboss and load some really light 44mag loads.   It is a bulky powder and easy to load.  This is the definition of a cowboy load if you use lead bullets.

When I was reloading for my S&W 629 I kept Unique for light loads and H110 for hot loads. Light loads from the 44 mag can be shot by girls for hours, hot loads would really thump. I was shooting 240 grain lead bullets on the light loads.

OP, probably the best course of action for you would be to stay with all .44 Magnum loads, just load a few at true magnum levels and load most light for target shooting.

Same brass, same bullet, same primer but you’ll probably need a different powder for “target” loads than whichever you use for the full power magnum loads.