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Why are .40 bullets flat nose?
- Thread starter Mylhouse
- Start date
FP .40 bullets
The bullets were originally designed that way to allow the maximum bullet weight, feed reliably, and to be short enough to fit in 9mm size gun's magazines. Anything longer and you'd have to step up to a 10mm or .45 sized frame, which has a longer overall cartridge length and generally a longer trigger reach. Generally, this would mean a bigger gun. This is what the designers wanted to avoid.
The .40S&W round was meant to duplicate the characteristics of the 10mm FBI load (10mm 'lite'), but in a smaller package. The 10mm was adopted by the FBI after the infamous Miami shootout. The problem was that the 10mm is a fierce round, recoil is severe. Testing by the Bureau to find that 'magic bullet' load that could do it all. They wanted increased power over the then-issued 9mm or .38Spl duty rounds, with a specific requirement for penetration both in free air and after passing through barrier tests, but still not overpenetrate or recoil like the full power 10mm or .45.
They settled on the 10mm bullet diameter as a compromise between magazine capacity and knock down power. Testing showed the optimum bullet weight to be around 180grs and optimum velocity to be around 950-980fps. The problem was that the 10mm guns were rather large, so the ammo makers went to the drawing board and came up with the .40S&W, that as mentioned before, duplicated the ballistics of the 10-lite but fit into a smaller '9mm-sized' gun.
I hope this helps a little.
The bullets were originally designed that way to allow the maximum bullet weight, feed reliably, and to be short enough to fit in 9mm size gun's magazines. Anything longer and you'd have to step up to a 10mm or .45 sized frame, which has a longer overall cartridge length and generally a longer trigger reach. Generally, this would mean a bigger gun. This is what the designers wanted to avoid.
The .40S&W round was meant to duplicate the characteristics of the 10mm FBI load (10mm 'lite'), but in a smaller package. The 10mm was adopted by the FBI after the infamous Miami shootout. The problem was that the 10mm is a fierce round, recoil is severe. Testing by the Bureau to find that 'magic bullet' load that could do it all. They wanted increased power over the then-issued 9mm or .38Spl duty rounds, with a specific requirement for penetration both in free air and after passing through barrier tests, but still not overpenetrate or recoil like the full power 10mm or .45.
They settled on the 10mm bullet diameter as a compromise between magazine capacity and knock down power. Testing showed the optimum bullet weight to be around 180grs and optimum velocity to be around 950-980fps. The problem was that the 10mm guns were rather large, so the ammo makers went to the drawing board and came up with the .40S&W, that as mentioned before, duplicated the ballistics of the 10-lite but fit into a smaller '9mm-sized' gun.
I hope this helps a little.
Precision sells a 155gr. bullet that I would decribe as a round-nose-semi-wadcutter. It has a distinct shoulder, and kind of pointed tip. I loaded it for 10mm so the shoulder would be just clear of the barrel leade. The rounds are over recommended max OAL, but they fit in the mag.
I'm sure this has been covered before, but humor me if you will. Doesn't the flat end slow the bullet down? What, in your opinion is the best 40S&W ammo (flat nose, hollow point, etc.), in what grain? I only have seen flat nosed 40S&Ws and hollow points. Does anybody make a hardball 40S&W to increase velocity?
The flat end isn't going to slow the bullet down any more than a hollow point will. I don't think you're going to give up much velocity due to wind resistance when comparing flat nose to ball. I've never seen a .40 S&W ball round.
It's good to see that you are making use of the search feature on the forum. But you can start your own threads to ask these questions rather than dragging up threads with thirty or forty posts to them. Just a suggestion. Some of the old posts are fun to read again. Some of them are just old.
It's good to see that you are making use of the search feature on the forum. But you can start your own threads to ask these questions rather than dragging up threads with thirty or forty posts to them. Just a suggestion. Some of the old posts are fun to read again. Some of them are just old.
The biggest reason that you see flat point ammo on .40 rounds is pressure. The .40 operates at fairly high pressures and if you have ever examined a 180gr FP or JHP bullet you will see that it is relatively long and fits deep into the cartridge case.
Flat point ammo allows for a slightly higher weight with a shorter overall length than ball ammo. Shorter overall bullet length means less pressure. Studies have shown that each thousandths of an inch deeper a bullet is seated in a .40 SW case beyond normal, the pressure rises dramatically. If you try to seat a standard FMJ bullet to the same cartridge OAL (overall length) you will see that the FMJ bullet is deeper in the casing. The .40 already works with limited case capacity, so this can be disastrous.
Slim had mentioned that the first run of bullets made by winchester was made by old 38/40 rounds. This can be done with lower overall pressures due to the lead bullet. A soft lead bullet creates lower pressures than a jacketed bullet.
Can a bullet lighter than 185 grs be loaded in the FMJ configuration without the bullet going deep enough to generate excessive pressure?..Yes, but everyone seems to be happy with FP ammo- and with the FP ammo if you have a round somehow push deeper into the casing, you will still be within acceptable pressure limits to a point.
Good Shooting
RED
Flat point ammo allows for a slightly higher weight with a shorter overall length than ball ammo. Shorter overall bullet length means less pressure. Studies have shown that each thousandths of an inch deeper a bullet is seated in a .40 SW case beyond normal, the pressure rises dramatically. If you try to seat a standard FMJ bullet to the same cartridge OAL (overall length) you will see that the FMJ bullet is deeper in the casing. The .40 already works with limited case capacity, so this can be disastrous.
Slim had mentioned that the first run of bullets made by winchester was made by old 38/40 rounds. This can be done with lower overall pressures due to the lead bullet. A soft lead bullet creates lower pressures than a jacketed bullet.
Can a bullet lighter than 185 grs be loaded in the FMJ configuration without the bullet going deep enough to generate excessive pressure?..Yes, but everyone seems to be happy with FP ammo- and with the FP ammo if you have a round somehow push deeper into the casing, you will still be within acceptable pressure limits to a point.
Good Shooting
RED