Can someone explain why lighter bullets do more damage than heavier bullets?

[Doug.38PR]

Can someone explain why lighter bullets like the 110 gr cause more damage to guns than heavier bullets like the 158 gr?

I've always heard this in being cautious in shooting medium frame .357 magnums and .38 specials (with +P cartridges). Not that it is dangerous to you, it's just in the longrun unhealthy for the gun. But why is this? With the energy and recoil you get from the heavier bullet (not to mention effectiveness) you would think the exact opposite would be true.

Which brings up another question...why would someone use a round that is does less damage to the bad guy and more damage to the gun in place of a round that will do more damage to the bad guy and less damage to you gun?

 

[unspellable]

light vs heavy bullet

A lighter bullet builds up more speed by the time it hits the forcing cone than a heavier bullet does. Puts more stress on the forcing cone. A light bullet with a light load is no problem since it isn't going so fast. With some loads the powder is still burning as the bullet passes the gap promoting erosion.

At the other end of the trip, a light bullet may be more effective than a heavy one due to higher velocity. There are a LOT of vairables here such as bullet placement, bullet construction, etc. But in general revolvers operate in a velocity range on the border where bullets begin to behave like bullets instead of rocks. A slow heavy non-expanding bullet will just poke a hole. A faster expanding bullet will often do more damage.

 

[redneckdan]

more energy. ke=.5mv^2

 

[Action_Can_Do]

A heavier bullet will penetrate more however.

 

[SAWBONES]

Sure. It's because they don't.

Bullet wound channel damage is a function of projectile size, mass, and velocity, and also in some measure fragibility, for those bullets that don't hold together.

For equivalent velocities, calibers and bullet configurations, a heavy bullet will do more damage than a lighter one.

 

[Sharps Shooter]

The "bullet wound channel" in the gun SAWBONES? Sorry - couldn't resist. Try reading Doug .38PR's question again.
It's a good question by the way Doug. It's something I've wondered about seeing as how I heard a long time ago that hot 110gr and 125 grain loads in my Ruger Security Six would destroy its forcing cone. I always wondered if there was any truth to that, and why.

 

[RyanM]

I read that the wrong way too initially.

The main reason is because lighter bullets usually have stiffer powder charges behind them. More powder at the same pressure means more gas, which causes greater gas cutting, erosion, and other associated damage. Light bullets also usually go at a higher velocity, which causes more in-bore friction and wears the barrel out faster. A lot of those varmint caliber rifles that go 4000 FPS+ only last for a few thousand shots before the barrel has to be replaced.

 

[Doug.38PR]

A lighter bullet builds up more speed by the time it hits the forcing cone than a heavier bullet does. Puts more stress on the forcing cone. A light bullet with a light load is no problem since it isn't going so fast. With some loads the powder is still burning as the bullet passes the gap promoting erosion.

At the other end of the trip, a light bullet may be more effective than a heavy one due to higher velocity. There are a LOT of vairables here such as bullet placement, bullet construction, etc. But in general revolvers operate in a velocity range on the border where bullets begin to behave like bullets instead of rocks. A slow heavy non-expanding bullet will just poke a hole. A faster expanding bullet will often do more damage.

http://www.hipowersandhandguns.com/38 Snub Ammo Test.htm

It looks like from the above link that heavier rounds in fact have better penetration AND better expansion than lighter rounds.

 

[Sharps Shooter]

That makes sense to me. Thanks Ryan.

 

[johncross]

Correct me if I'm wrong, going back to the original post I think it should be noticed that the terms"lighter bullets","+ P "bullets" and "high velocity bullets" are not the same,it's the overpressure what might cause damage on the gun (+P ammo stand for "plus pressure") because the gun might not be strong enough for the explosion made by those loads (compared to a standard load),that's why many 38 sp revolvers specify they can take + P ammo.(There is a maximum pressure for each caliber defined by SAAMI,there are many 38 special revolvers that were made before +P ammo was invented)).
Part of the confussion might be originated in the fact that +P ammo is designed to achieve more velocity with the same bullet weight than a standard pressure load,but as it was noted by Ryan there are many factors,being weight only a part of the ecuation,a light bullet may in fact be slower than a heavier one.(depending on the powder,barrel lenght,etc)
On the other side of the gun there are again many factors involving terminal ballistics in humans that it's kind of a never ending debate,"fast vs. slow","light vs. heavy" etc...we know that JHP bullets need certain velocity in order to expand but sometimes expantion equals underpenetration and the other way around...most tests are conducted in ballistics gelatin not in humans, so its difficult to know,we humans are much more complex than gelatin...and there would be a lot less of forums on the internet also...

 

[S&Wfan]

Obviously you are talking about .357 rounds.

Those light, 110 grain defensive loads really beat the heck out of a revolver's forcing cones. They are doubly hard on aluminum frame, "Airweight-type" revolver frames. You definately want to go heavy bullets with them. More on that in a moment.

Generally, the 110 grainers are also real "flamethrowers" when fired during the times when a defensive revolver is most likely to be used for defense . . . at night! That huge flame will temporarily cause the shooter followup problems.

Worse, lighter bullets exit the barrel quicker, before the barrel has risen as much . . . and this means a lower point of impact on the "target" with all handguns. I'd only use a 110 grain in a .357 revolver that I couldn't get to shoot high enough (probably in a fixed sight revolver) . . . and before I'd do that, I'd do a little filing on the front sight! (NOTE: I wouldn't do this either . . . I'd go to a heavier bullet until I found the one that would shoot to point-of-aim, of course!)

Another concern, especially in short barreled guns that don't weigh much, is that the stout recoil can cause primers to back out a little . . . and thus wedge in and prevent the cylinder from turning. Not good when the chips are down.


THE 125 gn. bullet also is kind of rough on guns . . . but not as much, and it is a much better round to use, IMHO.

FOR SNUBBIES . . . I recommend neither for defense. Instead, go up to the 158 grain bullet . . . and in a LEAD bullet at that! Lead bullets are generally "nicer" on forcing cones. Yep, the famous 158 gn. Lead Semi-Wadcutter HOLLOW POINT round. It is gentle on the guns, and has a wonderful street fight record out of short barreled guns. Several companies still make this load in hot velocities!

Hope this helps!

 

[fastbolt]

Can someone explain why lighter bullets like the 110 gr cause more damage to guns than heavier bullets like the 158 gr?

Okay, considering only the cause more damage to guns part of the question, I copied this part of Page 14 of the current S&W Safety & Instruction Manual, Revolvers - Modern Style -

ALL SCANDIUM REVOLVERS FIRING MAGNUM AMMUNITION

WARNING: DO NOT USE MAGNUM® LOADINGS WITH BULLET WEIGHTS OF LESS THAN 120 GR. THIS WILL REDUCE THE POSSIBILITY OF PREMATURE CYLINDER EROSION.