Effective Difference

[Electrified]

I have 2, .45 cartridges, #1 is a 230g, 950 fps @ 461 ft/lb...#2 is a 165g, 1250 fps @ 573 ft/lb. Help me to understand the real difference between the two. Why would I choose #1 vs #2 (or any size in between for that matter) for self defense purposes? I do not really understand the differences (of course I do know #1 is a heavyer weight)....Looks like its time for a lesson in ballistics...Thanks....
Bob

 

[browningguy]

Assuming similar bullet designs the heavier bullet usually gives better penetration. But either one would work.

 

[the naked prophet]

As long as you're getting "enough" penetration (minimum 12 inches in gelatin, though I prefer more) then I would personally go with the faster load. Why? I figure the shock of the faster bullet might cause more physical sensation of being struck than the slower bullet (even if there's no physiological reason for the person to stop).

That said, I prefer enough penetration that if the bullet penetrates an arm, then hits the side of the torso, it's got enough to reach the vitals. That usually means 14-18 inches of penetration. To get that, you usually have to pick the heavier bullet weights in a controlled expansion JHP.

My carry load is the Double Tap 9mm+P 147 grain Gold Dot @ 1100 fps. That's as fast as the standard pressure 115 grainers but much heavier. The Gold Dot petals should fold back farther when it hits faster than it was designed for (and the DT loads drive it up there), which should increase penetration. Yes, the expansion won't be quite as big (well, the expansion will reach a maximum and then go down a little), but I prefer the little extra penetration versus the little extra diameter.

So, I can't tell you which load is better. If your lighter faster load can penetrate 14-18 inches in gelatin, I'd carry that. You'll have to test them or look up previous tests to know that.

http://www.firearmstactical.com/ammo_data/ammodata.htm

 

[rockstar.esq]

So to African game hunters and advocates of the 9mm/ sub .45 cal crowd there is no greater objective than "penetration" real or imagined.

While it's true that it's possible for a person to present themselves as a target requiring 14" of penetration to hit "vitals", it's also true that a frontal shot to the chest would require less than half that to exit the body. Should you have chosen the "penetration" option you might have a liability problem due to bystanders.

Personally I think a much ignored aspect of cartridge selection is that of energy transfer. That is to say that the kinetic energy delivered by the bullet getting efficiently transferred to the target. This is where the hollowpoint design concept got it's roots. Personally I have seen much evidence to suggest that hollowpoints hitting bone at handgun velocities tend to damage the bullet to the point that expansion is limited. Sometimes ending up as an exited bullet (pretty much the same outcome as a high velocity cartridge).

So at the risk of getting slammed I tend to prefer large diameter slow moving slugs which will likely stop in the target thereby delivering all their energy into the target regardless of whether bone is struck. In the unlikely event that I'm presented with a 14" deep target, I'd rather shoot that target twice than risk hitting a bystander with the infinitely more likely frontal shot.

As an added caveat I don't worry about "shooting through cover" as I'm not a LEO.

 

[sm]

I concern myself with if the loading runs the gun and if goes where aimed.

Gun has to feed and extract and magazines are part of the semi-auto being able to function every time.
Then I like for a load to go to where aimed POA/ POI [Point of aim / Point of impact ]

Me? Well the 1911 was designed to run with 200 grainers. Military "said" they wanted 230 grainers. So I run / prefer bone stock 1911s as JMB designed the durn thing with the load he designed it to run with - 230 grainers and some 200 gr reloads 99% of time.

Shot placement I concern myself with, so the gun gotta run, and hit POA/ POI.

Penetration I either don't worry about - or way down the list...Not going to do me any good if a load penetrates "on paper" and don't go bang when it is supposed to.

Hardball been working for sometime I hear...

 

[James T Thomas]

you asked for it!

I believe the advise posted by the "naked prophet," (what a pseudonym; even John the Baptist wore animal skins!), ...is good to consider.

Some rounds are designed and manufactured to provide "rapid expansion," while others "controlled expansion."

If you can find the gelatin tests for your particular round you may be able to determine from observation whether your round abruptly expands or gradually expands as it penetrates. This phenomenon corresponds with the "wound volume" data that sometimes accompany the gel testing. A large volume being indicative of early and rapid expansion.
The final expanded diameter can be misleading. Wound vol. and gel block observation are a better predictor of performance than the penetration ratings often.
Gelatin being of uniform density; however, bullets often strike bone, etc. initially.

The projectile property called " sectional density" is a far better "index;" that is, an abstract mathematical rating for comparison, than penetration of gel is.
If you are familiar with the rifle rounds of the 6.5 "Swede" or even the ubiquitous 30-06 round; they are examples of sectional density effect on projectile penetration. (Perhaps this phenomenon accounts for the comparisons between the 45 ACP and the 357 mgn; if both rounds expand to consume half their length, then the 357 will have a greater length remaining than the 45 to provide the sectional density needed to maintain traveling velocity? Perhaps.)

The 45 slug at approximately 45/100 of an inch cross section would provide you with a multiplying factor of 1.4 in favor of the 230 gn round over the 165 one -both unexpanded. For this example neither weight nor cross sectional area have changed. S.D. is simply the bullet weight or mass (I forget which), divided by it's cross sectional area. Ballisticians and mathematicians please help!

However, expand the 165 gn round to approx. 65 caliber for example, and now you have decreased the sectional density of that round; by increasing the diameter, by a factor of approx. 2.9! This conjecture presumes little or no loss of bullet mass such as jacket seperation. The kinetic energy is mostly consumed in the expansion work, and when rounds expand, and they lose that sectional density to the degree these would, then the "brakes are on." It is in effect a dynamic transitional change that occurs. The higer velocity is used up rapidly. A bullet that expands rapidly but penetrates partially may not have the trauma effect you desire.

Kinetic energy being a measure of work; the upset or musrooming of the bullet head. The round comes to an abrupt stop. Sometimes short of the vital organs you intended to perforate.

What to rely on, or make an educated judgement upon then?

I look for the heavier rounds, and ones that are specifically designed and manufactured for that "controlled expansion." Particularly in handgun rounds.