FMJ Designs
Caseless
November 13, 2003, 03:31 PM
Anyone can tell me what's the difference between "pointy" FMJ, e.g. 9mm Luger and flat-nosed FMJ ammo, e.g. 40 S&W, ballistically?
Any difference in accuracy, penetration, etc, assuming all else is equal?
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Mikul
November 13, 2003, 04:05 PM
The flat-nosed 9mm or .40 S&W is less aerodynamic than its flat-nosed cousin. For longer-ranged shooting, it'll slow down long before the round nosed bullet will. I doubt you'd notice at anything under 25 yards.
The extra drag afforded the bullet by its shape will translate into less penetration. The flat nose will have a tendency to smash into a target while the round nose does more of a piercing. The flat nosed bullet will, for the same reason, be more likely to impart all of its energy into a target.
The flat nosed bullet will cut more material from paper and cardboard targets than a round nose will.
I used round-nosed 9mm almost exclusively, but mostly because they're commonly available Most of my shooting would be well-served by a flat-nosed bulet.. I have flat-nosed bullets for when I'm shooting plastic poppers because they don't fly right through. I have a special load of 9mm developed for penetration and it uses a round-nosed jacketed bullet.
CWL
November 14, 2003, 01:18 AM
I think that the flat-nosed FMJs originally came about as the best way to pack X-amount of lead grains into Y-caliber bullet & still allow for positive feeding. These tend to be heavier bullets like 147gr 9mm and 180gr .40s. Don't think performance was original intent of design.
Flatnosed FMJs do tend to crush/destroy material better than round-nosed, which can sometimes displace target material rather than crush it.
Hal
November 14, 2003, 05:46 AM
Mikul gave a very nice layman's introduction to:
- Ballistic Coefficient
- Sectional density
- Meplat
Suggest plugging all three of those terms,,,one at a time,, into your favorite search engine for links to greater details.
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