I'm new here and to all of this. Can someone help explain to me the difference in ammo. I understand caliber and fmj, hp. And such. What makes fmj good? And the difference in grain, what does that effect?

FMJ ammo is generally used for target practice. Difference in grain = weight of the bullet.

No single forum post will fufill your vauge question. An entire book could be written to answer that and still probably leave out details about what makes certain rounds "good"

 

I would suggest googling around for a couple evenings, using keywords such as bullet types, ammo types, bullet styles, what makes ammo good, how to make accurate ammo etc. and keep reading articles untill your head hurts. If you have any specific questions, try searching them on google and if you turn up empty handed, post them up here.

I agree with Krdshrk that FMJ is best for target shooting. FMJ is a lead core with a copper casing. They are usually heavier than FMJ and the bullets are usually pointed in modern rifle calibers making it more aerodynamic. The grain of the bullet is the overall weight of the bullet. The heavier the bullet the more resistant it will be to wind shift making it more accurate over longer distances. The problem with heavier grain bullets is that it will drop quicker than a lower grain bullet. The key is to view the distance and terrain then choose the best load to hit the target. According to what I have found some guns like certain ammo brands and grains better than others. Your best bet will be to first buy a few boxes of different types of ammo. Then site them in short range then test it over long distances to see what types of groups you get.

I agree with Krdshrk that FMJ is best for target shooting. FMJ is a lead core with a copper casing.

 

Define "best"

 

FMJ is typically most cost effective, however the most accurate for target shooting is a JHP (jacketed hollow point) due to the center of gravity more towards the rear (for accuracy), a better profile for cutting the paper (makes life easier), and since the jacket is drawn from the bottom it has a precise jacketed base, wheras a FMJ has an open base. This also promotes accuracy and a cleaner round.

 

FMJ does not have to be a lead core OR copper casing. It just has to have a complete jacket, thats all. There are mild steel & cupro-nickle jackets over steel cores, and those are still FMJs. Just not common place in modern ammo, thats all.

Bullets: lead round nose (L-RN) and full metal jacket-round nose (FMJ or FMJ-RN) are just about the LAST bullets used in target shooting. Their claim to fame is that all guns should be able to feed and chamber them. However, they are NOT the most accurate so you will see few in Bullseye competition or other competitions where accuracy, over speed of hitting, is the name of the game. lead wadcutter (and plated wadcutter) bullets are used in certain cartridges for best accuracy and they cut very clean holes in the target so scoring is easier and less subjective. Bullets look like small soup cans. Some have hollow bases and some don't. lead semi-wadcutter (and plated semi-wadcutter) have a significant shoulder at the bore bearing surface to punch clean holes and a nose section that is generally designed to hit the gun's feed ramp at the same location as round nose bullets. These are "the" accuracy lead bullets in most revolvers and semi-autos. Full wadcutters are basically only used in .32 S&W Long and .38 Special, whereas SWCs are used in those two cartridges and almost all other straight-wall cartridges. jacketed hollow points are the "normal" self -defense rounds with a hollow cavity in the nose of the bullet. These bullets are almost always the most accurate and, where a wadcutter or a semi-wadcutter is not deemed adequate, will be on the line at Bullseye matches--particularly Nosler 185gn JHP in .45Auto. Bullet weight--the lighter the bullet, the lighter the recoil and higher the velocity. This is true as far as physics goes, but in action pistol shooting, most shooters want the gun to recoil back and not up. Thus, for non-compensated action pistol guns, heavier bullets loaded as light as possible to make power factor is preferred. However, the use of very heavy bullets for the cartridge and very fast powders has probably contributed to many of the KBs in those sports. Heavy bullets can encroach on the case web and will produce extremely high pressures for very small increases in charge weights or very small decrease in COL (if bullet sets back). All of this is covered in reloading manuals and you should consider reading a reloading or shooting manual.

The problem with heavier grain bullets is that it will drop quicker than a lower grain bullet.

 

I believe Sir Isac Newton would disagree with this. What determines the bullets trajectory is its "time-in-flight". Gravity cares little about the mass of an object.

I believe Sir Isac Newton would disagree with this. What determines the bullets trajectory is its "time-in-flight". Gravity cares little about the mass of an object.

 

This is quite true.

 

I think of a bullet as a little football. A bullet follows the same trajectory as a football. It's not just how strong a quarterback throws the ball (velocity out of the barrel) but the tightness of the spiral also matters a lot. A heavier bullet is a denser bullet and a denser bullet can spiral tighter and faster. But, the smaller the cross-section hitting wind, the less it will be affected by wind.

 

By the rules of war, the military uses FMJ for the most part and can't use hollow points. FMJ isn't better, it's just a rule of war from 1899.

Reverse drawn jackets have the max strain hardened copper up at the tip where the bullet first engages the rifling (that's good) but the weakest copper at the base so there is a risk of the bullet coming apart with hot loads (bad but low risk). Conventionally swaged FMJ is cheaper.

 

Just an extra two cents on that

And regarding spinning the bullet, you have to consider the Magnus moment and the bullet's strength to hoop stress so it's not just faster=better

And regarding spinning the bullet, you have to consider the Magnus moment and the bullet's strength to hoop stress so it's not just faster=better

 

Also if the bullet spins too fast the nose will maintain a more constant angle relative to the ground resulting in inreased drag.

Also if the bullet spins too fast the nose will maintain a more constant angle relative to the ground resulting in inreased drag.

 

This is something I've wondered about. We've all seen a long football throw and the ball's nose (angle of the ball) follows the same trajectory of the ball. Does a bullet do this or does it drop while the bullet's angle stays steady (more like an airplane when it lands)?

 

Anyway, the physics can get quite complicated and difficult to understand and predict.

Both a bullet and a football undergo precession it's just that you're not throwing a football 1000 yards so it doesn't matter (those "lame duck" passes or ones that get tipped will have a lot of precession, enough to see it at 30 frames per second on TV)

 

Some bullets will wobble a whole lot and come back under control, some start out fine and go crazy at the end of the flight, everything is a variable in order to drive reloaders crazy EDIT: if you have a few years to waste, start googling "shot dispersion" or something like that, people spend careers trying to make bullets predictable after they travel extreme distances

 

Boy this thread has changed focus, eh?

Head now spinning must reboot to regain proper axis

Seeing some inaccuracies in this thread, so remember, don't believe everything you read!

 

No one has even touched on rifling twist rates, lighter and heavier bullets and the ft/lbs of energy they carry, etc, etc. T

I believe Sir Isac Newton would disagree with this. What determines the bullets trajectory is its "time-in-flight". Gravity cares little about the mass of an object.

 

Correct!

 

So when you fire a heavier bullet compared to a lighter bullet in the same caliber, you will experience more drop because they are SLOWER than their lighter counterparts, therfore take more time to reach the target, thus allowing gravity more time to impact its flight.