Howdy
I may sound like a broken record, but it is not the frame that determines how strong a cartridge a revolver can take, it is the cylinder.
If something is going to let go from too much pressure, it will be the cylinder, not the frame. Of course, if the cylinder bursts, it may take the top strap of the frame with it.
Study this photo. From left to right, the cylinders are Ruger 'original model' Vaquero, Ruger New Vaquero, Colt Single Action Army. All three are chambered for 45 Colt.
I have answered this question so many times that I wrote down some dimensions and saved them in a Word file.
Ruger Blackhawk----------------------- Length 1.700, Diameter 1.726, Distance Between Chambers: .060
Ruger 'original model' Vaquero-------Length 1.701, Diameter 1.728, Distance Between Chambers: .060
Ruger New Vaquero-------------------- Length 1.610, Diameter 1.673, Distance Between Chambers: .042
Colt Single Action Army 2nd Gen----Length 1.608, Diameter 1.652, Distance Between Chambers: .045
Uberti Cattleman------------------------- Length 1.618, Diameter 1.672, Distance Between Chambers: .043
The point is, the large frame 'original model' Vaquero had a large cylinder, with about .060 between chambers at their narrowest point. Since this discussion is about a 44 Mag, the chambers are slightly smaller and the distance between chambers will be slightly greater. Notice the Blackhawk and 'original model' Vaquero cylinder share the same dimensions. Their cylinders are the same size, and their frames are the same size too.
Now, notice the New Vaquero, Colt SAA, and Uberti Cattleman all have almost the same amount of metal between chambers. The frame of the New Vaquero is a bit smaller than the 'original model' Vaquero, approximately the same size as a Colt SAA. That is why the New Vaquero is only recommended to be shot with SAAMI max loads, no Ruger Only loads. The same with the Colt and the Uberti Cattleman. The New Vaquero has never been chambered for 44 Mag because even though there would be a little bit more metal between chambers than a 45 Colt, it is not enough for the pressure developed by the 44 Magnum cartridge.
If a Ruger says 44 Magnum on the frame, it is safe to shoot with factory 44 Magnum ammunition. With the Vaqueros it can be confusing because they recently started stamping Vaquero instead of New Vaquero on some of their frames.
Things used to be simple when Ruger simply stamped VAQUERO on the frame of what I call the 'original model' Vaquero
When they started making the smaller New Vaquero, that is what was marked on the frame.
Recently they have started stamping VAQUERO, on some of the New Vaqueros, which does not help at all.
Of course, when they came out with the name New Vaquero I thought that was a dumb move in the first place. What will the next one be called? New and Improved Vaquero?
Major dumb move instead of doing the smart thing that they did with their iconic 22 semi-automatics. Mark I, Mark II, Mark III, and now Mark IV. You pick up a Ruger 22 and all you have to do is look at the frame and you know exactly what you have.