Grain Count?

[Stag 0]

I understand grain count most likely has to do with the speed at which the bullet travels out of the barrel (?), but is there anything else I need to know about grain count when buying ammo? Like, can a 9mm handgun fire 9mm rounds with any grain count? Is it tied to any legality issues in NJ? Does ammo get more expensive depending on it?

[hd2000fxdl 422]

I understand grain count most likely has to do with the speed at which the bullet travels out of the barrel (?), but is there anything else I need to know about grain count when buying ammo? Like, can a 9mm handgun fire 9mm rounds with any grain count? Is it tied to any legality issues in NJ? Does ammo get more expensive depending on it?

 

Grain is the weight of the bullet..

[RedBowTies88 41]

7000 grains in a pound

[Stag 0]

Grain is the weight of the bullet..

Wow, I was way off...

 

So what does the weight of the bullet matter in practical application? Is it something I need to consider when buying ammo?

[RedBowTies88 41]

all translates to muzzle velocity, a variable bullet weight over a static load will produce different muzzle velocities. Lighter bullets will generally have a flatter tajectory and heavier bullets will generally carry energy better over longer ranges and also penetrate more.

 

Also heavier bullets fired at similar velocities as a lighter bullet will be less effected by things like windage and less likey to be deviated by hard objects like bone.

[njJoniGuy 2,131]

Lighter bullets can be driven faster than heavier ones

Heavier bullets pack more "punch" than lighter ones

 

Momentum=Mass times velocity

Energy=Mass times velocity times velocity times 0.5

[EMB 1]

Is there any difference in perceived recoil based on bullet weight?

[Regulator72 80]

It also depends on what you like and what your gun likes. In my Sig 226, I prefr 124gr 9mm over 115gr. The 124 "feels" better to me.

[HKHockey 5]

A quick Wikipedia link to what +P ammunition is.

 

http://en.wikipedia.org/wiki/Overpressure_ammunition

 

Keep in mind that there is a specific guideline for making +P ammunition but not ++P

[raz-0 1,259]

Is there any difference in perceived recoil based on bullet weight?

 

Yes, although there's no hard in fast rule as to how a round will feel as it is dependent on the design of the gun, caliber, bullet choice, and powder choice.

[Shocker 151]

Momentum=Mass times velocity

Energy=Mass times velocity times velocity SQUARED times 0.5

 

Fixed.

 

Edit: missed the second velocity.

Reading > me

[compujas 21]

Fixed.

 

No, it was correct. It had velocity in there twice already. Now it's .5*m*v^3

[jcpg 4]

It also depends on what you like and what your gun likes. In my Sig 226, I prefr 124gr 9mm over 115gr. The 124 "feels" better to me.

 

I've only shot 115 through my 226 how does heavier grain affect POI?

[hd2000fxdl 422]

I've only shot 115 through my 226 how does heavier grain affect POI?

 

Also can matter at a USPSA match, some 115gr were making sub-minor..

[Melgamatic 66]

Grain is the weight of the bullet..

 

Just to be clear, when you look at pre-loaded ammo, the weight in grains is the weight of the bullet (e.g., 115 gr 9mm), but we should mention that we worry about grain weights when reloading or making our own ammo, and that we weigh the powder charge in grains, as well.

 

"John used 3.4 grains of Blue Dot when he loaded those 115 grain bullets"

[RedBowTies88 41]

Also can matter at a USPSA match, some 115gr were making sub-minor..

 

sorry the OT, but i've been wondering..how do they measure power factor at events? specially if someone hand loads

[hd2000fxdl 422]

sorry the OT, but i've been wondering..how do they measure power factor at events? specially if someone hand loads

 

With a Chrono, it will give you FPS (Feet per Second) you take that number X the GR bullet / 1000 and that would be your PF.

 

Say a 180 Gr Bullet, 920 FPS would be 180X920/1000=165.6 PF

 

They don't have them at all the local matches but are that on occasion and you need to be ready...

 

Actually thats how I found out some of the 115gr ammo didn't make Minor PF.

[RedBowTies88 41]

and they just take the word of the shooter for bullet weight? or do they weight the cartridge to try and get an estimate?

[HKHockey 5]

"The power factor is calculated by multiplying bullet weight (in grains, 7,000 to the pound) by muzzle velocity (in feet per second), then dividing by 1000. As of 2008, a value of 165 or greater is considered major, while values below 165 are minor"

 

Edit - Wow I was late on that reply.

[M4BGRINGO 139]

If you do knockdown steel events don't use the 115 grain 9mm stuff. If you do, plan on shooting high on the plates to get them to tip-over, dead-center will move it back some, but not always enough to fall. Ask me how I know...........

 

Sounds nice but not enough poop.

[Pizza Bob 1,488]

Major PF > 164

 

Minor PF > 124 < 165 except in IDPA SSR division where Minor > 104

[raz-0 1,259]

and they just take the word of the shooter for bullet weight? or do they weight the cartridge to try and get an estimate?

 

Depends. At local matches, we usually take your word. At a major match they will pull the bullet and weigh it.

[RedBowTies88 41]

10-4, thanks for clearing that up. it just seemed too easy for someone to handload something super light and compete with 0 recoil I knew they must of had some way to test

[Ronald Silver 2]

Is this true?

The less the grain, the more recoil you get from the same caliber?

[Pizza Bob 1,488]

Is this true?

The less the grain, the more recoil you get from the same caliber?

 

No

[compujas 21]

Is this true?

The less the grain, the more recoil you get from the same caliber?

 

It's dependent on a lot of things, including bullet weight and velocity. Typically heavier bullets are at a slower velocity, so you can get less recoil, but it's not guaranteed.

[Qel Hoth 33]

If my logic is working correctly today, (assuming the same amount of energy transfer is involved) a lighter bullet will result in a higher impulse than a heavier bullet. The higher impulse would make the recoil seem more harsh or sharp with the lighter bullet, and the lower impulse would make the recoil of a heavier bullet seem to be more of a push. The actual force generated however would be the same, again assuming equal energy transference.

 

Whether or not the difference in impulse between a 115gr 9mm and a 147gr 9mm is enough for a person to perceive, I do not know though.

[Vlad G 345]

I think as a rule of thumb it is better to forget bullet weight as measure of recoil in the same cartridge. There is simply no relation. The amount of powder and powder burn rate have far more to do with perceived recoil then anything else.

 

From a physics standpoint there are two components to recoil, the part that happens before the bullet leaves the barrel, and the part that happens after. For the first part conservation of momentum says as forces push the bullet forward, equal forces push the rest of the system back. The problem is defining what affects the force pushing the bullet forward and how much of the work done by the powder is actually used to push the bullet. For a moment consider the idea of shooting a under caliber bullet through the barrel, and you will note that most of gases leave the muzzle without actually pushing the bullet. More of that energy goes into pushing the bullet if it engages the rifling. Then you have the idea how much contact is there between the bullet and the rifling, and how much reverse spin the bullet inflicts on the barrel and gun. Depending on the amount of powder and burn rate of the powder you end up with vastly different "feel" for the recoil even if you are driving the same weight bullet out the muzzle at the same speed.

 

And then there is the second part of recoil, after the bullet has left the muzzle. Long after it has gone its marry way, the gun still has forces acting on it from the gases escaping. I'm sure everyone has seen slow-mo videos of a gun firing and all the smoke and flame and ejecta after the bullet has left the gun. What does that image remind you of? It should remind you of a rocket engine, because that is what you have. Shooting high pressure gases out of a small hole is how we put people on the moon so while those gases are leaving the barrel you are still exerting considerable pressure pushing the gun backwards. Again the amount of powder and burn rate will make a huge difference here because a more voluminous slower burning powder will generate more gasses and more recoil but a powder used in small quantities with a faster burn rate will generate less gas volume and ejecta (as a rule of thumb).

 

You an take the same bullet weight, and shoot it from the same gun, at the same speed using two different powders and get vastly different recoil feel, generally speaking with faster powders feeling "softer".

 

So the question then becomes why not always use fast burning powders? The draw back of fast burning powders is pressure. Because the burn faster they tend to reach their full volume and full pressure long before a slower powder but that means there is less time for the bullet to move forward and make more room for the expanding gasses.

 

Anyway, the point of all this is that you can load heavy bullets to feel soft, or light bullets to feel soft, the questions is not the bullet weight, but how you move it and how fast you move it.

 

This doesn't even account for the fact that recoil feel has a lot to do with acceleration (the rate at which the recoil gets delivered to you) then the total amount of force delivered.

[JLHockeyKnight 0]

Grain is the weight of the bullet..

 

Interesting.

 

Stag, I made the same mistake.

 

Learn something new every day!

[JLHockeyKnight 0]

Just to be clear, when you look at pre-loaded ammo, the weight in grains is the weight of the bullet (e.g., 115 gr 9mm), but we should mention that we worry about grain weights when reloading or making our own ammo, and that we weigh the powder charge in grains, as well.

 

"John used 3.4 grains of Blue Dot when he loaded those 115 grain bullets"

 

So does the grain count for the bullet affect the amount of grains of powder in the cartridge? Or is it generally the same?