MY large-bore "magnum" pistol is a 7.5" Ruger Redhawk in .45 Colt. Using "T-C/Ruger Only" loads, it launches 250-260 gr. projectiles at up to 1460 f/s. This is fully the equivalent of any factory .44 Magnum load, and perhaps a bit more. These loads produce significant recoil, somewhat more than a 6.5" M29 with full-power factory loads, and are best approached in a step-wise manner. They are nonetheless "manageable ENOUGH", in small quantities, for hunting or metallic silhouette shoots, when approached gradually in training with reloads developing ~1000 f/s, ~1150 f/s, ~1300 f/s, etc. Because power levels like these are not mass-produced for .45 Colt, I have no choice but to create them.
In .44 Mag., there is, of course, the .44 Special, which reminds me of shooting .38 Spl. target wad cutters in a medium or large frame .357. EXCELLENT for mastering trigger & breathing control! There are also "+P" .44 Special loads, which are well short of what the Honorable Elmer Keith developed (240 gr. @ ~1150 f.s), but are still a step up from factory. These are expensive, but very useful for training.
At one time, one of the major ammo producers manufactured a "mid range" .44 Magnum load, which developed ~1000 f/s with a 240(ish) gr. LSWC. These were scarce, expensive when available, and one of the best tools available for the the non-reloader to "train up" to truly mastering full-house .44 Magnum factory loads. Such loads MAY be available from one of the "boutique" ammo makers, but amounts large enough for training likely cost more than all the equipment and components (plus many useful & convenient extras) required to reload one's own ammunition.
You don't mention what model(s) of .40 S&W, or .45 ACP you shot, so it is difficult to characterize a .44 Magnum's recoil in terms of those. Compared to my 5" 1911A1, loaded with my "maximum performance shoot seldom/carry often/hope to never have to use" reloads (215 gr, LSWC @ 1079 f/s), I'd expect a 6.5" M29 with 240 gr. factory loads to recoil about half-again as much. I would also expect it to recoil at least 2/3 MORE than a full-size 1911A1 with factory ball.
If you can find a box of Buffalo Bore Standard Pressure .45 Colt ammunition (
STANDARD PRESSURE HEAVY 45 COLT OUTDOORSMAN), run them through your Uberti Cattleman. Expect the 6.5" M29 with 240 gr. magnum loads to kick 1/3 to 1/2 more.
FRANKLY, unless your life will simply not be complete until you own a S&W M29 (and there ARE guns out there for which I have
exactly this feeling), I think I'd look into reloading "slightly warmer" loads for your Uberti Cattleman. A 255 gr. LSWC leaving the barrel at ~1000 f/s will accomplish almost everything a full-house .44 Magnum round will, plus be kinder to your shooting hand.
And now....
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CAUTION: This post discusses loads or load data that equals or exceeds published maximums for the cartridge(s) mentioned. Neither the writer, The Shooter's Forum, nor the staff of The Shooter's Forum assume any liability for damage or injury resulting from using this information. DO NOT ATTEMPT TO DUPLICATE THE DESCRIBED LOADS without first working them up from a published safe starting level charge while watching for pressure signs. If you don't know how to do that, don't try.
CAUTION: This post discusses experimental load suggestions that either are not published anywhere or have not been properly tested for safety and may exceed published pressure maximums for the cartridge(s) mentioned. Neither the writer, The Shooter's Forum, nor the staff of The Shooter's Forum assumes any liability for damage or injury resulting from using this information. DO NOT ATTEMPT TO DUPLICATE THE DESCRIBED LOADS without first working them up while watching for pressure signs. If you don't know how to do that, don't try.
Okay, now that THAT'S out of the way,
ALLIANT POWDER RELOADER'S GUIDE
(Alliant Powder - Reloader's Guide) lists a maximum load of 9.5/Unique/250 gr. LSWC. From their 5.5" (probably unvented) test barrel, they list a velocity of 941 f/s. From your Cattleman's 7.5" barrel, you would likely exceed 1000 f/s. The use of polymer-coated projectiles, which seem to engender greater lubricity than cast lead, may also help increase velocity, without having to elevate charge weights.
A 250 gr. projectile (I prefer RNFPs) leaving a muzzle at 1000 - 1100 f/s hits like a medium sledge hammer, at any distance from which the shooter is likely to connect. Its trajectory is not as flat as a factory .44 Magnum will be, but this is where sight adjustment and/or shooter familiarity come in. I dare say that, if a game animal is NOT downed by such a load from a .45 Colt, a .44 Magnum used under the same conditions would not have accomplished the task, either.
May you find my opinions of value.