Bullet Weights

[olp73]

It seams to me that the pro- guys prefer heavier bullets for uncompensated guns. Like around 200gr for 40sw and that the 147gr. is popular in 9mm. Or at least it used to be like that. It this still true? And what is the reason for this? Wouldn’t a lighter speedier bullet make the gun return to target faster? If this is the case, heavier bullets should be a good choice for someone that is less experienced because it spreads the recoil over longer time?

Olp73

[Kingman]

heavier bullets in non comp guns have more of a push than a snap.

Some even have very little muzzle flip when worked up properly.

[mcoliver]

Just like springs, it's a personal feel kinda thing.

[Jasonub]

leatham loves heavy heads since it pushes the hand instead of slapping it. The burner use 180s since it snaps and does not push.

personal thing, try both and decide what you like

[Dave Marques]

I'm sure this doesn't help , but I'll chime in with the same answer -its a personal preference. It also can be firearm dependent too!

The bottom line is try some different wts and see what ya like.

[RogerT]

Has anyone tried the 300 gn (Hornady? I think) lead pointed .45 bullet in a revolver?

I'm considering loading 230 gn FMJ's today for fast and easy reloads with the clips, and have not yet explored the possibilities of other bullet weights.

There are 200 gn FMJ's with similar "easy loading shape" as well, but I have only fired 230 gn in the gun so I don't know how much "snappier" the lighter bullet is in a Major load.

[Skywalker]

olp,

as everybody else pointed out, it's a matter of personal preference.

But there is another factor that comes into play: PF .

The threshold for Major PF is not the same all over the world: IPSC threshold is 170, and this means that almost everybody who wishes to play on the safe side shoots at least 175 PF; while USPSA has a Major PF threshold at 165, thus the majority shoots above 170.

This, IMO, may account for the big difference in bullets weight selection.

Here in Italy, most of top shooters shoot a 200grainer, while I acknowledge in the USA most of top shooters shoot 180grs bullets.

Again, you have to try what works best for you.

I have been doing a bit of experimenting by myself, and eventually settled on 180grs bullets over 200, because I determined I was (consistently) slightly faster in reacquiring my sights on the second shot (sort of .07s on a popper-sized target @ 15m). It's snappier than a 200grs, but less pushy and slightly faster (for me).

[Julien Boit]

Guess what ! I'm gonna say like everybody else

Try all the load combos you can and decide which one works best for you.

I'm shooting 170 grains in 40sw since 5 or 6 years now and I like a lot the feeling in my pistol. Plus I found them the most accurate bulltes in my pistols (Fiocchi 170 FMJ)

I also tried 200s and 180s: 200s feel too slow for me. 180s are OK, but the 170s are a lot more accurate .

[Norm Lee]

Hey Mr. 73:

There's certainly a good argument for "personal preference" and there's probably another having to do with accuracy when deciding on bullet weight. But here's a little something worth chewing on.

So far as I can tell, the bullet's contribution to recoil is independent of its mass at a given power factor as the contribution comes from its momentum. That would mean that real (as opposed to perceived, say) differences in recoil would be due to the contribution of other ejecta. Burning gasses, etc. I assume that the amount of gas generated by burning powder is pretty much directly related to the amount (mass) of the powder. (Ideally it would all convert to gas)

Since the equations used to calculate recoil assign signifcant velocity to the gas, there should be a significant reduction in recoil to be achieved by using less powder. That's my rationale for using fast powder and heavy bullets.

The reason for not carrying this to its logical exterme is that pressure builds unacceptably quickly when using fast powders behind really heavy bullets.

Cheers,

Norm

[Gun Geek]

I've been the purveyor of several big posts and long threads about this subject. But I have had time to boil down my story on this, so here goes

1) This is a preference issue, but it is interesting to understan why the loads feel different.

2) People usually make a mistake when they design the loads to do the compairison. Just as Skywalker says, the issue is power factor, and the mistake is in correctly determining the necessary load to make PF. For example, to make a 170 pf with a 45 acp, a 230gn bullet need to be going 717 fps, while a 165gn bullet has to go 1000fps. The loads to achieve these 2 extremes will be VERY different. My experience is that people don't drive the light bullets fast enough to make the numbers.

3) I think the physics behind this is energy conservation (yes there is disagreement). The point is that you, the shooter must absorb the same amount of energy through recoil as is imparted as kinetic energy (velocity) to the bullet. The trick then is to make the energy as low as possible.

4) The formula for kinetic energy is K = 1/2 m x v ^2 (one-half mass times velocity squared). So, because of the square issue, the heavier bullet going slower requires less energy (less recoil) than the lighter bullet going faster. The lighter bullet does it quicker so we feel more of a snap then a push - this is where the preference comes into play.

So, the advice is - make up the loads and be sure that they meet PF. Then take them to the range and decide which one you like (we heard this before)

[shred]

So far as I can tell, the bullet's contribution to recoil is independent of its mass at a given power factor as the contribution comes from its momentum.

Aaa.... not "what is recoil?" again...

At the same PF, a light bullet has more kinetic energy than a heavy one. Since that energy didn't just appear mid-flight, it actually is more recoil on the gun-end. But, powder choices and amounts pretty much make that irrelevant.

The bottom line is : Heavy bullet/small amount of fast powder = feels like less recoil, but more 'sluggish' operation. Light bullet/more powder = more felt recoil, but 'snappier'-- gets back on target faster. Don't go to extremes, just pick one and practice.

[Norm Lee]

Suppose we eliminate the recoil effect contribution of the powder. We’ll just assume there’s a powder choice that can be made so that we achieve desired PF for different weight bullets using exactly the same amount of powder. Different powder to be sure, but the same mass. So when we fire the gun the bullet of mass Mb heads down range at Velocity Vb. Newton’s third says the firearm, mass Mf goes up range at velocity Vf in satisfaction of the equation MbVb=MfVf.

At the same power factor the MbVb product will be the same for all bullets. So if the lighter bullet is half the mass it must be traveling at twice the velocity and it will have 2 times the kinetic energy.

The mass of the firearm is the same, as is the velocity. Same recoil energy as before.

But I guess it’s really just a perception and preference issue.

Cheers,

Norm

[shred]

You're working in Momentum (MV), not Energy (1/2 M V squared). That would be true if there were absolutely nothing pushing the bullet-- it just teleported into the barrel at a given velocity, but we have to accelerate that bullet up to speed. That takes powder.

If we had a magic powder such that 10 grains, say was good for 100pf no matter what the bullet, the light bullet load would still recoil more-- more energy has to be used to get the bullet accelerated up to the speed needed.

Accelerating a light bullet to 100pf takes more energy than accelerating a heavy bullet to 100pf. That extra energy has to go somewhere.. it's transferred to the gun as the equal-n-opposite reaction to accelerating the bullet.

[mcoliver]

Has anyone tried the 300 gn (Hornady? I think) lead pointed .45 bullet in a revolver?

Wow 300gr? You'll only need to run it about 560 fps to make major, right? You can practically finish a COF and whistle a tune before your bullets hit the targets at that speed.

[Norm Lee]

Hi Shred:

Can you set up the equations to prove your hypothesis? I am anxious to learn how this energy thing works. Thought I had it figured out.

Cheers,

Norm

[Gun Geek]

Norm:

Momentum is conserved only during collisions. There are several types (elastic, inelastic, and plastic I think). Elastic - hit and stick together (M1V1 = M2V2), Inelastic - hit and bounce off, Plastic - hit and stick, but some momentum goes into deforming the objects (real world).

Momentum is not conserved when a bullet is fired. The very nature of firing a bullet is to change momentum by converting forms of energy - the powder ignites and expands to convert chemical energy into mechanical energy (pressure), which propels the bullet.

The quantity conserved is energy, not momentum. So the issue about more energy required to make PF with lighter bullets is why the recoil is more with lighter bullets. The personal preference is the choice of a shorter heavier recoil over a lighter longer recoil (and the action of the gun).

I didn't say this before, but the heavier bullet set-up works best with lighter springs in the gun. I have tried heavy bullet loads in factory spring 45's and don't like it at all - feels like the slide is moving way to slow. Reducing the spring rates returns the timing of the gun to normal, as well as the "back-on target" timing. The slide is not so sluggish and this tends to shorten the snap. What you get is the better "feel" of the light bullet load with the lower recoil of the heavier bullet load. This may be the part of the story that gets left out. People probably just load up a heavy bullet load and try it in a heavy spring gun and it sucks.

Try a light bullet load in a lightly sprung gun and you'll get a real eye-opener! Feels like the slide is going to come back and hit you in the forehead

I tried the combos (heavy bullet/light spring, light bullet/light spring, light bullet/heavy spring and heavy bullet/heavy spring) with a timer. The heavy bullet/light spring was by far the fastest, and it was very repeatable.

[olp73]

Thank you that is the kind of answers I am looking for. I have never really believed that two loads with the same pf have the same recoil only different feel. Not that it is impossible to like fast bullets in standard guns, but that there are some objective answers out there, even tough maths has never been my field.

[shred]

Most basic physics books (and the SAT test) stop at momentum conservation for the firearm/projectile system. The powder energy calculation is just too complicated and variable, and momentum is a pretty good approximation, just not the whole story.

[Gun Geek]

Has anyone tried the 300 gn (Hornady? I think) lead pointed .45 bullet in a revolver?

Wow 300gr? You'll only need to run it about 560 fps to make major, right? You can practically finish a COF and whistle a tune before your bullets hit the targets at that speed.

I have tried some 300gn SWCs that were made for the 45 Colt cartridge. Worked great, but you could see the bullet going down range and it was very distracting. I also couldn't easily find springs (per my post above) that would restore the timing of the gun (1911 45 ACP) so it felt sluggish.

It also caused lots of qeustions from other shooters and SOs.

Also, I was using Clays powder and was getting some signs of pressure problems. Not much, just a few flattened primers.

I think all of this could be worked out with a little tweaking if you were really motivated.

There is another interesting effect with heavy bullets. They tend to hit very high compared to Point of Aim. The explanation I've heard is that the slow bullet stays in the barrel long enough that the unlocking of the barrel lug (causing the barrel to rotate upward) and/or the rotation of the barrel caused by recoil launches the bullet with a slight upward trajectory. This could probably be compensated for, but it seems this might be a source of inaccuracy.

[shred]

There is another interesting effect with heavy bullets. They tend to hit very high compared to Point of Aim. The explanation I've heard is that the slow bullet stays in the barrel long enough that the unlocking of the barrel lug (causing the barrel to rotate upward) and/or the rotation of the barrel caused by recoil launches the bullet with a slight upward trajectory.

Actually this happens with revolvers too and is a perfect example demonstrating that the gun starts moving in recoil before the bullet leaves the barrel.