SWC Meplat

[Petrol & Powder]

I've read that the size of the meplat of a SWC should be 60%-75% of the bullet diameter. Given the same bullet weight and diameter, changing the size of the meplat will change the length of the bullet. A larger flat point is better for terminal performance but if accuracy is the main criteria;
Is there an advantage to a smaller meplat (closer to that 60% number) which gives a slightly longer SWC bullet with all else equal?

[Outpost75]

My experience has been that handgun bullets having a meplat larger than about 0.7 of bullet diameter produce non-linear dispersion beyond 50 yards. While subsonic handgun ammunition having a huge meplat over 0.75 of diameter up to 0.8 might shoot well at 25 yards, my experience has been that at standard blackpowder velocities, whether with BP or smokeless powder, they won't even stay on the paper at 100 yards. Traditionally-shaped .44-40 bullets such as John Kort's Accurate 43-215C produce dispersion which is proportional to the range well out to 600 yards.

I've found this to be true in both revolvers and Cowboy rifles in .32-20, .38/.357, .44-40 and .44 Magnum, as well as .45 Colt.

Others here have claimed that this statement is BS, but I welcome pictures of actual targets posted from anybody who can show me a series of TEN-shot groups fired consecutively on the same piece of paper, using WFN bullets with meplat of 0.8 of diameter, at 100 yards, without excluding any data.

There are no "lucky" ten-shot groups... Let the flames begin!

[Bigslug]

I too have experienced the dispersion issue with a 75% meplat, though it was with a 400+ grain .45-70 WFN. Great out to about 150 yards; was coming seriously unglued at 200.

I like to joke that Elmer Keith must have been mad at the world when he designed the 452423 for the .45 Auto Rim; that's another 75% meplat bullet that has a reputation for starting to disperse much past 50-75 yards.

The thing to remember here is that the instability doesn't really start until the bullet has gone farther than a lot of folks bother trying to reach with a handgun, and accuracy to that point can be quite good - match wadcutters being the prime example of this phenomenon. If the name of the game is pigs in heavy cover, or deer from tree stands, the terminal effect of such things is quite gratifying.

If longer shots are in the offing, Keith's 358429, 429421, and 454424 are all more conservative in their nose diameters, and all enjoy a good reputation for accuracy at distance and ability to kill stuff. He was after the happy medium when he cooked those up, and history would indicate he found it.

[rintinglen]

I have a Lyman 452-389 that casts upwards of .457. Now the 389 is a button nose wadcutter that runs about 200 grains IIRC. I loaded up a hundred in 45-70 cases over 22 grains of 2400 and took them and my Marlin CB out to the range. At 25 yards I managed a nice 7 shot group that was well under two inches. At 50 yards, the groups was still respectable, albeit not proportionate to the the 25 yard group. AT 75 I got fliers and groups opened up markedly. At One hundred yards, they would not stay on the target. At two hundred yards, they were hitting 6 feet away from the point of aim in a random sequence that could never be called a pattern. I also have somewhere tucked away a single cavity 454-424 that I had enlarged until it casts .458. That boolit shoots reasonably well at a hundred yards from the same Marlin.

I do not know how wide a meplat must be before it causes trouble, but absolutely believe that it can.

[Petrol & Powder]

Thanks, so it looks like keeping the meplat under 70% of the diameter is the way to go if the bullet is going to have a flat nose.

[Outpost75]

Thanks, so it looks like keeping the meplat under 70% of the diameter is the way to go if the bullet is going to have a flat nose.

About 70%, under 75% is a good number. Lately I've been getting away from SWC bullets, but have been using modern Accurate ogival-nosed LFN designs:

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[Petrol & Powder]

Outpost75 - Thanks for that information.