Hey folks,
I just purchased this revolver:
https://www.smith-wesson.com/product/n-frame-163638
I'm using it for bear protection.
What is the maximum grain/type of ammo that I can use?
Example: Can I use these.... Heavy .44 Magnum 44A, 44D?
Can I use flat nose ammo?
Also, what is the muzzle velocity of this revolver?
Thanks,
Techsent
You're link shows the M629 with 6 inch barrel that tips the scales at just under 50 ounces. That's pretty much the epitome of what Elmer Keith's work on heavy .44 loads had in mind.
When the .44 magnum was introduced the basic load used a 240 grain bullet swaged into a copper "half-jacket" and had a "soft nose" (You don't hear that term much any more). Remington, in concert with S&W didn't just orbit their collective fingers over a circle of different bullet weights to come up with that number, it was derived from real-world data that's impossible to duplicate today.
"True magnum power" is defined as one-kilojoule of ballistic energy at 1,300 fps. ANY genuine .44 magnum load fired from a barrel four inches or longer exceeds one kilojoule, and depending on barrel length, 240 grain loads range from 1.2 - 1.4 KJ. From a 6 inch barrel expect to easily meet or exceed Underwood's published velocity numbers.
Underwood lists a 305 grain load and a "+P" 340 grain load that reaches 2.0 KJ of energy. let's dismiss the 340 grain load because it's imparting 35% MORE breech thrust than a top .44 magnum load. I would not shoot such a load in any .44 magnum I cared about, I would instead choose a .460 or .500, both of which easily out-power the .44 magnum - more on that point in a moment...
As for the 305 grain load, it's putting 21% more stress on the breech for a return in "power" of just 15%. When we have the 255 grain delivering 1.4 KJs at 1,325 fps (probably more from the 6"), and the 255 grain will shoot clean through a bear, a moose, an alligator, etc., of what practical value or need is that extra 50 grains of bullet? (the weight of a single .25 bullet)?
To shoot the 305 grain load is to needlessly place more strain on your gun, subject yourself to more recoil, and derive absolutely nothing you needed in terminal performance from it! (Other than bragging about shooting 305 grainers versus those pitiful, weak 255 grainers!). A better approach would be to bump the 255 grain up another 100 fps to extend shockwave distance.
Back to breech thrust: When a fixed breech revolver is fired, the bullet goes screaming down the barrel trying to rip it clean off the front end due to tremendous friction between bullet and bore driven by expanding gas. At the same time an equal and opposite pressure shoves against the recoil shield trying to blow the back out of the gun - the steel in the middle is placed under a high tensile load which just so happens to be one of steel's best strengths, but every single time that gun goes boom, the forces in play are trying to snap that top-strap and, over some number of shots, leads to frame stretching, and last time I checked nobody has built a revolver that can't be blown up, which means nobody has built one that can't be dimensionally altered by the use of extremely heavy loads. Granted, most sane people probably never shoot more than a box or two of the hottest loads, but when you break down the numbers it's quite clear even shooting 305 grain loads is needlessly stressing the frame for very little power gain, when all available "standard weight" bullets are more than powerful enough to handle the job.
As a hand loader there is a very simple "rule" I apply when considering load development. Take the so-called "standard load" and multiply bullet weight x velocity, then divide by the desired, higher weight bullet and you're looking at the velocity that produces the same recoil stress on the breech. This simple formula can save a gun from being blown up because if we load to the resultant velocity number, we're not just holding the line on strain on the frame, but we're also limiting pressure. With a little checking you'll quickly find a direct correlation between this formula and factory ammo, especially ammo for moving breech firearms that need to operate within a reliability parameter.
For example, the original .44 magnum load was 1,400 fps / 1,044 fpe (1.4 KJ) from a long barrel. Using that as a baseline:
1,400fps x 240gr. / 255gr. = 1,317 fps which is just 8 fps less than Underwood's published number for their 255 grain hard cast.
To match breech thrust the 305 grain load should be limited to around 1,100 fps, (1.1 KJ) and the 340 grain limited to 988 fps / 737 fpe (1.0 KJ). By hand loading the 340 grain could be safely pushed to 1,100 fps / 913 fpe (1.2 KJ). Of course we see these loads give up the value of supersonic shock wave impact which the early pioneers of magnum loads certainly observed and exploited by biasing their load development toward speed over added mass.
You will see the developers of magnum handgun rounds kept the standard bullet weights, experimenting with higher velocities and bullets shapes more effective at transferring shock. In the first half of the 20th century the true nature of air molecules compressed to and beyond the speed of sound was not known, but what they had observed was that blunt nose bullets impacting above, to well above the speed of sound had a much more immediate effect than bullets impacting at subsonic speeds. This was not easily quantified because the moment a bullet leaves the barrel it is slowing down and pistol profile bullets accelerated beyond the speed of sound slow down very quickly due to the high drag created by a "cone" of incompressible air molecules radiating outward from the nose and shoulder edge, or even nose ogive. The faster a handgun bullet is going on impact with a juice-filled target, the more violent is the effect of the supersonic shockwave - seen in milk jugs and wallermelons as complete vaporization, and in body shots on animals as an immediate collapse due to neural shock caused by the shockwave radiating throughout the body, or seen in hits to boney areas such as skulls and joints and explosive destruction from both shockwave and the kinetic energy imparted. Bullet shock can cause an animal to collapse - much like a hit from a Taser, even though the bullet didn't create an immediately mortal wound. We see it in the hunting field all the time - the animal is hit by the supersonic bullet, goes down, then within seconds is back up running for the hills - the bullet DID shock the animal, the hunter failed to strike anything immediately lethal or incapacitating.
Doubling velocity quadruples kinetic energy - a round worth looking at is Underwood's Lehigh Defense "Penetrator" solid copper 220 grain with the "screwdriver nose" loaded to 1,530 fps / 1,144 fpe (1.5 KJ) (conforms almost spot on with the "rule" described above).
Magnum ballistics do not apply to low-power handgun rounds used in self defense shootings as most have less than 400 joules of energy and are subsonic - hence the notion that the bullet must auger out a hole sufficiently to damage enough tissue to cause incapacitation.
