Energy, Bullet Weights, & Short Barrels

[Kind of Blued]

I understand that any factory hollowpoint is fine for self defense, but there are a few things that I don't understand about bullet weight/velocity correlation.

I'm looking at 9mm and .38 Special defense loads on Double Tap Ammunition's website and much of what I'm noticing is that the lighter bullet consistently produces more muzzle energy than the heavier bullet. I thought it was the case that any given cartridge has an "ideal" bullet weight which may be anywhere in the possible spectrum for that load.

I understand that heavier bullets retain their energy more effectively over a distance, so does this create a rule of thumb? The closer the target the lighter the bullet, or is it dependent upon the cartridge?

I'm looking at this data with my small carry guns in mind i.e. SHORT BARRELS and UNACCOMODATING GRIPS. From what I understand, recoil has more to do with bullet weight than anything else. Would the lighter 115gr. 9mm and 125gr. .38 loads make the most sense considering recoil? Also because a self-defense situation would be within very close range?

Here's the data I'm referencing:

9mm +P Loads
115gr @ 1415fps / 511ft. lbs. (from a G17)
Glock 19 velocity - 1395fps

124gr @ 1310fps / 473ft. lbs. (from a G17)
Glock 19 velocity - 1295fps / 462 ft. lbs.

147gr @ 1135fps / 421ft. lbs. (from a G17)
Glock 19 velocity - 1120fps

Is there any special consideration needed for my short-barreled handguns? Would the 115gr. load produce more muzzle energy out of ANY barrel length?

Sorry for all of the questions. One final question: Am I putting too much importance into muzzle energy in the first place?

 

[C-grunt]

Muzzle energy will be higher because of the higher velocity. E=mc(squared). When dealing with kinetic energy, speed creates more than mass.

Now with bullets I think its a good reerence to use when comparing but thats it. I prefer heavier bullets because the greater mass will lose energy slower when moving through material therefor giving it more penetration.

 

[tipoc]

Would the 115gr. load produce more muzzle energy out of ANY barrel length?

They generally do. But as you already found the Buffalo Bore loads are hotter, and their 124 gr. loads are hotter, than some 115 gr. loads from other manufacturers.

In general the heavier rounds tend to penetrate more deeply but this too also depends on bullet construction and the specific loads.

Looking at the kinetic energy available is a useful thing to do. It tells you how much energy is available for the bullet to do it's work, such as bucking the wind, penetrating, expanding, etc. But it is one of several things worth looking at. The others being bullet construction and whether the round works reliably in your gun and is as accurate as you'd like it to be from your gun.

Is there any special consideration needed for my short-barreled handguns?

A few rounds these days are made specifically for short barreled guns. Personally I'm not sure if this is another way to market or if there is some real benefit. I just don't personally know. I know that for decades there are rounds that have worked well in snubbys. In .38 Winchester and Remington both offer well respected 158 gr. LSWCHP loads that have worked from snubbys for years. For the 9mm several have worked well.

In .38 the difference in recoil between a 125. gr. bullet and a 158 is hardly noticeable. Usually the heavier round will penetrate more deeply.

You can drop by here to see some of their results...

http://www.brassfetcher.com/9mm Luger.html

or here... http://www.theboxotruth.com/

If you drop by here you can see a little of what ammo is available and the specs for it...
http://www.midwayusa.com/browse/Bro...3&categoryId=7508&categoryString=653***691***

Keep in mind that over the years some very good rounds have been developed none are substitutes for a well placed shot. Get a decent bullet but what works best and most reliably in your guns and what you shoot best I believe trumps a few extra feet, one way or the other of energy.

tipoc

 

[Kind of Blued]

Thanks for the replies!

I guess I didn't mentally tie the relationship between kinetic energy retention and the medium through which the bullet is traveling in regard to density. The bullet does the same thing in the air as it does in flesh "penetration-wise", just on an extended scale.

So basically the process is such:
1) Buy as many of the loads which show some potential in regard to grainage and velocity (as well as plain old popular loads regardless of 'the numbers')

2) Test these for accuracy in YOUR GUN as "only hits count".

3) Test the reasonably accurate loads on simulated targets (or look on the interwebs if you're lazy ).

Sound 'bout right?

 

[NG VI]

In a short barreled handgun generally the heavier bullets will lose less velocity than a lighter bullet in both absolute and percentage terms. So the heavier bullets tend to still be well within their operating velocities even with a three inch barrel. Check out this thread on Glocktalk, a guy just chronoed some 115 grain WWB through all the different 9mm Glocks. If you notice, the velocity loss from the G26 (3.25" barrel) vs the G17 (4.6" barrel) really isn't that much. And the defense-oriented 124+P Gold Dot he shot through the G26 was moving faster from the short barrel than the lighter 115 bullets out of everything except the two competition Glocks, the 34 and the 17L.


I think a good bullet is most important.

 

[Kleanbore]

much of what I'm noticing is that the lighter bullet consistently produces more muzzle energy than the heavier bullet.

The reason the lighter bullets have more energy is that the ones you are looking at have higher velocity. Energy proportional to the bullet weight and to the square of the velocity. Reduce the bullet weight (in a smokeless cartridge, where the mass of solid combustion byproducts is insignificant) by 20% and increase the velocity by 25% you have 25% more energy (.8 X 1.25 X 1.25 = 1.25).

From what I understand, recoil has more to do with bullet weight than anything else.

Recoil is based on conservation of momentum (the basis of Newton's third law of physics--for every action there is an equal and opposite reaction). Momentum is defined as mass times velocity. In the case of a gun, the total mass of the projectile plus other effluent (gas, plus black powder solid by-products if applicable) times the velocity is equal to the mass of the gun times the recoil velocity. So recoil is directly proportional to both mass and velocity. It varies less with changes in velocity than does energy.

I understand that heavier bullets retain their energy more effectively over a distance, so does this create a rule of thumb?

Traveling through air, velocity retention is actually a function of aerodynamic configuration and sectional density. A pointed bullet will perform better than a flat-nosed bullet, and a longer, thinner bullet with higher sectional density (more mass per unit measure of bullet length) will retain velocity better than a larger diameter bullet of the same weight. That's important in rifle caliber selection, but if you are comparing two 9MM bullets the heavier one will have greater sectional density. At SD ranges that has to be a moot point.

Did I address the gist of your question?

 

[the naked prophet]

My personal preference for short barrels is to use heavier bullets. This is why.

Lighter bullets go faster largely because there is more room for powder in the case. True, they also accelerate faster due to less inertia, but the extra powder has quite a bit to do with it as well.

In a short barrel, most of that extra powder will be unburned when the bullet leaves the barrel - making a brighter, louder flash and bang.

A heavier bullet will get closer to its maximum potential in a short barrel than a lighter bullet will, with less bang and flash - which means less perceived recoil.

 

[tipoc]

Just to add a couple of things. First off you may want to take a look here on rounds for a .38 snubby.

http://www.hipowersandhandguns.com/Feedingthe38Snub.htm

If you poke around that site you'll also see some thinking on the 9mm as well.

If you are thinking of handgun hunting at extended distances (100 yards or so) than thinking of sectional density and ballistic coefficient do come into play. For self defense than less so, as Kleenbore said.

If you can pick up a book by Robert A. Rinker called "Understanding Firearm Ballistics" it's very useful and deserves study.

Keep in mind that a gr. is 1/7000 of a pound so the differences in weight are not as great as they may at first appear.

Keep in mind also that few rounds have gone through as much testing and development in the last 20 years as the 9mm so you aren't starting from scratch. If you use the search function here there is a good deal available on the 9mm from barrels short and long.

Recoil in general from the 9mm is light. You'll have to feel it for yourself from your guns to know if, for you, it makes a difference. Felt recoil is also different from actual recoil. The recoil you feel will vary from one gun to another based on the grip, grip angle, etc. even in guns that weigh the same. So try different loads in your guns and see if they make a difference for you.

There are a number of very good loads for the 9mm Winchester's Ranger, Cor-Bons DPX, Federal Hydra Shok, etc. all available in different weight bullets. Which one works best for you from your guns for self defense does weigh heaviest, for me at least.

tipoc

 

[Kind of Blued]

Very very helpful. Thanks fellas.

 

[tipoc]

This fellas stuff may also be of some use...

http://stevespages.com/page8f9mmluger.html

http://stevespages.com/page8f38special.html

tipoc

 

[Kind of Blued]

Federal HST looks awesome!

The photos of them opened up are like Medusa... beautiful, and deadly.

I'm going to buy 6 or 7 boxes of different SD loads, save up milk jugs, and spend a long day at the range figuring it all out first hand. Should be fun.

 

[jfh]

Perhaps the best source of gelatin testing for short-barrel loads is at brassfetcher.com--here.

As for the direct questions at hand--the ballistic issues are pretty well addressed in the preceding posts.

I've done extensive shooting with short-barreled revolvers (1&7/8"-2&1/8"-2&1/2"-3"-4") in the past fifteen months to build a reloading database, and IMO there are other factors that are equally important for considerations of round performance in a real-world situation.

Most important, is the shooter's general ability and related hand conditioning. Simply put (as many of us have noted in other threads), the round that was a creampuff to shoot in my 39 oz 4" 686 (the GDSB38+P 135-gr. round) was a real handful in my 13.3 M&P 340 when I first started shooting it. As my hand became conditioned (and calloused), those problems faded.

For the lightweight revolver shooters, the Gold Dot Short Barrel loads seem to provide the best compromise in that eternal light-vs.-heavy penetration topic--e.g., a medium-weight bullet that does not quite meet FBI penetration standards but are tolerable to shoot. (As an aside--are there any extensive real-world results yet, a la Evan Marshall?)

Generally, I think the heavier-bullet / more penetration formula is more important for self-defense considerations. As a result, my current reloading tests are focussed on using 158-gr. bullets running at 1) 800 fps--the 38+P-pressure "FBI load", and 2) running a 900 fps--call it the "FBI900". That latter ballistic level is about the upper range at which a shooter with a lightweight revolver can comfortably shoot a cylinderful, reload, and shoot again.

Semiautos are generally easier to shoot than revolvers even in the compact / carry versions, but the (ballistic) issues are different. Factory ammunition for semiautos has long been formulated to provide adequate power for the cycling, and not just in longer barrels. Were I to carry a semiauto now (and I do carry a P3AT as an alternative), I would probably lean to the "heavy bullet" variation, as the HP bullet design / fragmentation characteristics of bullets at moderate velocities have been sorted out--see HST's picture above.

Jim H.