Modern guns chambered in .45 Colt aren't subject to the same limitations as the older ones. They'll easily match, and even exceed, .44 Magnum performance. There are plenty of commercially available loadings which do just this.
Sheesh, people!
:banghead:
I don't agree that all modern guns are good to go with hot .45 Colt loads. Neither do any of my reloading manuals. I suspect if you shot a modern gun other than a Ruger or T/C apart or even loose with heavy .45 Colt loads and explained to the manufacturer that you were shooting loads that were significantly over SAAMI specs as required to meet the performance of the .44 magnum that they would decline to replace your firearm under warranty. I can shoot commercial .44 magnum level rounds out of any .44 magnum all day long without worrying about voiding the warranty.
As far as the availability of commercially loaded .45 Colt ammo that matches or exceeds .44 magnum, your own links to Ballistics101.com says otherwise. A quick comparison reveals the majority of COMMONLY AVAILABLE commercial .45 Colt loads do not even come close to the mildest COMMONLY AVAILABLE commercial .44 magnum loads. Unless of course by "widely available" you mean a few loads from a handful of manufacturers only available by mail order and almost impossible to find in the average store. The nearest shop that carries ammo from Buffalo Bore, Underwood, and Cor-Bon is 2 hours away from me. Or I can drive 10 blocks and pick up some .44 magnum ammo that is at .44 magnum level.... and maybe sitting beside it is a box or two of .45 Colt loads running at 800-900 fps. So I think our definitions of "widely available" differ.
Modern revolvers are limited by the exact same thing as older revolvers...cylinder wall thickness and the quality/treatment of the steel. A New Vaquero is not any safer to shoot high pressure loads than any other .45 Colt revolver with thin cylinder walls just because it was made last week instead of 50 years ago. In many cases, modern guns that are manufactured for .45 Colt are not given the same treatment as guns manufactured for .44 magnum. Ruger makes their .454 Casull Super Redhawk out of an even tougher tool steel than their .44 magnum Super Redhawk.
There are only a handful of handguns I out of which I would consider it safe to shoot .45 Colt loads that match .44 magnum performance, and only three out of which I would shoot loads exceeding .44 magnum performance....All of them Rugers, Freedom Arms, or T/C's
An interesting article from Chuck Hawks on the subject;
http://www.chuckhawks.com/high-pressure45.htm
" For many years Smith & Wesson built a .45 Colt DA revolver on their large "N" frame that looked nearly identical to their .44 Magnum Model 29. I have been asked specifically about this revolver in the past, as their owners sometimes conclude that if the Model 29 can withstand the 36,000 psi (43,500 cup) of a .44 Magnum cartridge, their revolvers should be able to withstand the same pressure. BUT THEY CANNOT!
The reason is that the Model 29 is made from special alloy steel specially heat treated to withstand .44 Magnum pressures. S&W themselves have put this in writing in their advertisements, and a talk with one of their technicians will confirm it. NEVER use any high pressure .45 Colt load in a S&W revolver. They are designed to handle standard pressure .45 Colt loads ONLY.
The original model Ruger Vaquero is a fixed sight variation of the Blackhawk and falls under the "Blackhawk" classification, as is the Ruger Bisley version of the Blackhawk. These are cosmetic variations capable of handling the same pressure as the standard Blackhawk, and fall under the general heading of "Ruger Blackhawk revolvers." The "New Model" Vaquero, introduced at the end of 2004 primarily for cowboy action shooters (who use only low pressure loads), is built on a smaller frame--much like a Colt SAA--and is not recommended for high pressure loads.
The authors of the major reloading manuals were aware that there are modern guns other than the Blackhawk and Contender that are chambered for the .45 Colt cartridge. These include not only the Colt Single Action Army, Colt Cowboy, and the various replicas thereof, but the DA Colt Anaconda, Ruger Redhawk, aforementioned "N" frame S&W, and others. But no exception is made for any of these guns, not even the excellent Anaconda and Redhawk. Clearly, FOR BLACKHAWK AND CONTENDER ONLY means just that!
The following quote is from the section of the Speer Reloading Manual No. 13 devoted to high pressure .45 Colt loads, and reinforces this point.
"IMPORTANT SAFETY NOTICE. These loads are intended for use only in Ruger Blackhawk and Vaquero revolvers, and the Thompson/Center Contender. They are not to be used in any other make or model of firearm!"
The Hornady Handbook, 3rd Edition prefaces their high pressure data with this simple statement: "The following data is to be used only in the T/C or the Ruger Blackhawk."
My copy of the Sierra Handgun Reloading Manual makes this blunt statement in the first paragraph of their section devoted to high pressure .45 Colt loads.
"The data on the following pages were developed for use in the Ruger Blackhawk and the Thompson/Center Contender pistol in .45 Colt caliber. Both of these pistols are of stronger construction than any of the other makes chambered for the .45 Colt cartridge."
And from John Linebaugh
"This entire report is based on facts proven in the popular and strong Ruger Blackhawks and Bisley models chambered for the .45 Colt Cartridge. I have felt a need for a long time to set the record straight as to the full safe potential of this fine gun and round. This material is not about Colt SAA, Dakotas, or any other import. These are fine guns in their own realm, but require safe, carefully assembled handloads of much LESS PRESSURE than we are talking about in the Ruger Revolvers."
" By careful measurement and a little simple mathematics we find that the Ruger Blackhawk in .45 Colt caliber is approximately 80 % as strong as the Blackhawk in .44 magnum caliber."
http://www.customsixguns.com/writings/dissolving_the_myth.htm