how is WFN defined?

[Shadow9mm]

So I have seen Wide Flat Nose, Long Flat Nose, and Round flat nose.... How are these defined. I had heard WFN had to be a certain percentage of the bullets diameter but I cannot seem to find what percentage. I am also unsure how LFN and RFN are defined or differentiated... I spent a good little bit on google looking, was not able to find much.

[Outpost75]

No set definition. It is whatever the mold maker says it is.

[longbow]

Maybe no set definition but some general guidelines. I was going to say WFN was generally considered to be anything from 70% on up for meplat diameter... bigger than typical Keith style meplats.

So, I did a bit of looking before typing for once. From Glen Fryxell (http://www.lasc.us/Fryxell_Book_Chapter_9_MouldsMouldDesign.htm):

"Optimum meplat diameter. OK, so we know that a big meplat is a good killer, but that too much meplat makes a bullet unstable in flight. How much meplat is too much meplat? Let's look at a few successful designs for some guidance here. Elmer Keith started off with a meplat diameter of 65% by borrowing Heath's ogive and meplat for the Ideal 429336. Keith then used 75% on his 452423, then settled on 68-70% for his 454424, 358429 and H&G #258 (.41 Magnum). J.D. Jones has used 70-75% meplats for his SSK designs. The LBT WFN is profiled by making the meplat .090" less than bullet diameter, so the relative diameter is not constant (75% for .358", 78% for .410", 79% for .429" and 80% for .452. The Keith SWCs and the SSK FPs are some of the most accurate handgun cast bullets that I've ever shot, and while the WFN bullets are superb hunting bullets, and are capable of fine accuracy, there are reports that they can be finicky about delivering their best accuracy, and can tumble upon impact (just like a wadcutter). In contrast, the big-bore LFN bullets are generally regarded as being inherently more accurate than their WFN brethren, with far better long-range stability than the WFN designs, and the LFN's have a reputation for penetrating nice and straight and deep. The LFN meplat is approximately .140" smaller than bullet diameter, or 67% for .429" and 69% for .452". Ignoring the contribution of the forward driving band for a moment, a purely empirical correlation suggests that the optimum compromise between stable aerodynamic flight and maximum tissue crushing capability occurs with a meplat of about 70-73% of bullet diameter."

I believe it was Veral Smith of LBT who first used the terms WFN and LFN and that his WFN meplat was >70% of boolit diameter.

Having said that, I am no expert and read most of that on the internet and in gun magazines so take it for what it is worth.

Longbow

[charlie b]

First time I saw it was also from LBT. I agree with above about what it means, ie, a bit more than a TC or SWC design.

[44MAG#1]

Veral Smith was the first one I can remember using the terms Long Flat Nose, Wide Flat Nose and Wide long Nose for the Meplats and their diameter. Bullet diameter minus .130" for Long Flat Nose, bullet diameter minus .090" for Wide Flat Nose and bullet diameter minus .110 for Wide Long Nose
I have his book.

[farmbif]

just what it describes, a wide flat nose. I'm not so sure there is an exact percentage of bullet diameter or hard fast rules. I would not get too hung up on it.
but if its what your wanting your lucky to be casting now because there are more great bullet designs and custom mold makers than ever before, NOE, MP and Accurate are just a few makers of molds that have many bullet design options with a wide flat nose.
its just another bullet abbreviation that describes the type of bullet. there are many many bullet abbreviations for some more descriptive abbreviations take a look at page three of this load manual.

https://accuratepowder.com/wp-content/uploads/2010/09/WesternLoadGuide1-2016_Web.pdf

[gwpercle]

The best way to get an idea is to look at drawings and see how they are described .
There are no "set" specifications ...mold designs vary ... Lee has a few they call SWC but they are Truncated Cone in my opinion .
Just study mould designs and you will have a rough idea ... even round nose designs will vary !
Ain't nothing simple or easy in this game !
Gary