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Posted: May 11, 2007 9:01:15 am
Greg Edington

Hello All,

I thought that this old post might be of some interest.  I've added three illustrations that time and now technology of the new BB have allowed me to post.

Best Wishes:

Greg Edington :)

Wilkinson Bullet Update & Co-op Moulds

Hello All,

It?s been awhile since I last posted. I thought that I?d summarize my recent progress developing Wilkinson and William?s bullets, and detail future work. The Wilkinson bullet for those of you who do not know is a bullet that operates on inertia and gas pressure to expand by the means wedge shaped sections of the bullet. The Wilkinson bullet does not need a hollow base to expand so moulds for it are simple since they do not need a core pin to for a hollow base. The Wilkinson bullet being flat based is easier to cast and inspect than a Minie? ball.

My goals for the Wilkinson bullets are to make them lighter and more efficient. I think one way of doing this with Wilkinson bullets is to improve the ballistic efficiency of the bullet so that a lighter bullet has the same ballistic ability as heavier bullet, but a flatter trajectory since it goes faster down range. Wilkinson?s bullets? improvements in ballistic efficiency are possible since it is base cast and does not have a nose flat like conventional cast Minie? bullets. The large nose flats on cast minie bullets increase the amount of drag and the effect of wind on the bullet increasing wind drift and lowering the shooters hit probability.

The first new bullet is the new 58 caliber Wilkinson Improved Picket Mk III bullet weighing 445 grains. This bullet is an improved 58 caliber 450 grain Mk II bullet with a bevel/boatail base. The boattail which a minie' cannot have by its construction increases the subsonic efficiency of the Wilkinson bullet. The new Mk III bullet with a ballistic coefficient of 0.266 and a weight of 445 grains is 5 grains lighter and has a ballistic coefficient nearly 10% higher than the Mk II design. To give you an idea of how efficient the Mk III is the 530 grain Lyman 58 caliber New Style minie? has a ballistic coefficient of 0.198 or about 30% less than the Mk III bullet. What is the practical difference? I checked and it translates out to about 1? less drift at 100 yards (the New Style Minie? drifts about 2.5? in a 10 MPH wind.) I designed the Mk III bullet for a initial velocity of 1000 to 950 feet per second versus the 850 to 900 feet per second speed for the New Style Minie? design. The new 58 caliber Wilkinson Improved Picket Mk III bullet is now available in two cavity moulds for $45 postage paid for anyone who would like to experiment with it.

The second bullet is a joint project that I and Tony Beck did and detailed earlier on this board . The project sprang from an observation of mine that many original CW and repro rifle muskets need to be brushed out or cleaned of fouling after firing only 10-14 rounds. I know that this is far short of the ideal performance mentioned before the Civil War for such rifles of 100 plus rounds. I conducted a poll to get an idea of the extent of the problem and these were the results.

Poll: How often do you need to brush/wipe your barrel?

1 to 7 Shots = 7.7%
8 to 14 Shots = 30.8%
15 to 25 Shots = 15.4%
26 to 50 Shots = 15.4%
Over 50 Shots = 30.8%

Lube Formulas & Bullet Observations

I looked at the poll results and it seems that many skirmishing muskets need tor get cleaned after one to two events. I took a look at CW period lubricants ad it seems that most of the formulas had beeswax as a stiffening agent, and a high temperature animal fat such as Beef, or Mutton tallow, or Hogs Lard. My experience is that if soft lubes are used the lube tends to penetrate the fouling better and soften it so that a bullet can wipe away the fouling upon its passing though the bore. The main part of black powder fouling is Potassium Bicarbonate (Kalicinite) that has a Mohs hardness of 1 to 2 (Brinell 10-20) vs. soft lead which only has an hardness of 0.5 (for comparison your finger is 2.5 on the Mohs scale.) A soft lead bullet going down a bore with dry fouling is literally being sanded away leaving lead and contributing to the fouling problem.

One of the problems with fouling seems to be in part due to a gradual change in traditional commercial Minie' mould designs. The original "Ideal" New Style Minie' mould originally started out with deep grooves that have gotten more shallow over the years to the point were sizing a bullet down 0.005" nearly destroys the grooves. I think that the trick is to have nice square shoulders for the bullet grooves so the shoulders do a nice job shearing/wiping the fouling away and setting up a shuttlecock effect. The original Wilkinson and William?s cleaner bullets all have grooves with sharp edges (as do the slotted zinc washers too.) The prototype bullet that I and Tony Beck tested have these sharp edges to help clean away fouling through a shearing action (Kalicinite is brittle.)

The ability of a bullet to wipe away fouling is going to become more critical as the quality of black powder varies i.e. Swiss, GOEX, KIK, Wano, and Elephant all have different burning rates and fouling. I think as long as a decent powder and lubricant are used fouling doesn't become an issue, but not everyone can get better grades of powder or can afford it. Small bore (45 caliber) muzzleloading military rifles such as the Whitworth, Kerr, and Volunteer rifles are disproportionately hurt by todays lack of energetic powders as using more power creates more fouling, and creates an underbore condition where large amounts of unburnt powder are shot out. The black powder we use today would be considered from good to marginal by standards in effect for the Civil War. I think if you ask any 45-70 shooter the only powder available today that meets the ballistics for original period loads is Swiss black powder.

The US Army had major problems with slower burning black powder during the Civil War since the Minie'-Burton US regulation bullet was designed to use an excellent grade of DuPont Fg powder with a swaged bullet allowing 250 some shots to fired without significant fouling. The use of substandard powder forced the US Army to do several things. The first was changing the size of the Minie' used from 0.5775" (0.0025" Windage) to 0.574" (0.006?) to 0.57" (0.01" Windage) and back to 0.574". The second action was the purchase of roughly a 100 million William?s "Cleaner" bullets. The third action was the blending of good and black powders and upping the powder charge
to 65 grains of Fg powder. US Soldiers at Gettysburg and the Wilderness still had fouling problems despite the use ammunition using the much smaller 0.574" and 0.57 bullets, .

I used these criteria to design a new bullet to meet the issues of powder variability, fouling, skirmisher needs. The design goals were:
Weight: Below 450 grains
Design: Semi-wadcutter
Castability: Good to Excellent
Cleaning Ability: At least three sharp edges,

I and Tony Beck recently tested a prototype bullet meeting the above criteria, and I am currently testing the redesigned bullet using the lesson learned from this prototype. The bullet is a single piece William?s bullet design that is castable. The prototype new style William?s (NSW) bullet tested was 58 caliber 437.5 grain semi-wadcutter compression bullet with a dished bevel base. The newer bullet is the same style, but with more beariing area deeper fletching grooves, and a 430 grain weight. These bullets are based off of Elijah William?s & Henry Wilkinson's patents, but with modern improvements, and design elements added like improved transonic perforance and beveled boatailed bases. The NSW bullets works on the same principles as the Civil War William?s bullet design, but is N-SSA legal due to the single piece design. The tests of the prototypes that I and Tony Beck did indicate that the NSW bullet has a 40% ballistic advantage over the hodgdon Minie?, and gets 21% more power per grain of powder. The tests that I will be doing in the near term will compare the NSW bullet against the Lyman 575213 Old Style bullet a copy of the old US Army Minie' using chronograph data and zeroing targets to figure out the true accuracy and efficency of the bullets.

Finalized New Style Williams Bullet & the later Long Range New Style Williams bullet(GE 2007)

New Style William?s Bullet Test Results

Tests of the NSW bullet used the RCBS hodgdon semi-wadcutter minie' bullet as a control bullet since it is widely used and generally acknowledged as being a target type minie'. The analysis of the test data comparing the two bullets provided some surprises. The Hodgdon and new style William?s bullets are somewhat comparable in accuracy and point of impact if a faster burning brand of powder is used such as Swiss or GOEX as a minimum. The Hodgdon developed problems in the tests with progressive depth bores when FFg or other slower brands of powder such as Elephant were used. One indicator of this problem are the chronograph velocities of the control rounds. Tony Beck chronographed the following on a 75 degree day in 90% humidity using RWS musket caps with an original style nipple:

Prototype NSW Bullet 438 grains sized 0.576", lubed with
MCM/Beeswax mix

Load ------------------------ Vel.------ S.D.
45 gr. Elephant FFFg 904 fps 15.0
46 gr. Elephant FFFg 921 fps 10.7
47 gr. Elephant FFFg 928 fps 14.9
48 gr. Elephant FFFg 956 fps 10.0
49 gr. Elephant FFFg 964 fps 5.9*

Using ammo loaded with RCBS Hodgdons 400 grains sized to 0.576", lubed with
MCM/Beeswax Mix

Load ------------------------ Vel.------ S.D.

45 gr. Elephant FFFg 845 fps 18.3*
*Most accurate load tested

All in all with Elephant FFFg powder the NSW bullet gets 21% more power per grain of powder with progressive depth rifling than the RCBS Hodgdon bullet. I looked at these results and determined that since black powder is non-progressive in its burn rate the RCBS Hodgdon Minie' bullet should have chronographed at a faster velocity than the NSW bullet? The only reason for such a difference in velocity is if the RCBS Hodgdon minie' sealed the bore slower than the NSW bullet. Testers using FFg grades of Brazilian made Elephant black powder could not get the hodgdon Minie' to group well and had to go to the FFFg grade of that powder to get the hodgdon Minie' to group for the tests. The NSW bullet showed no problems providing 1-3" groups at 100 yards from different unmodified test rifles regardless of the powder or graduation (FFFg, FFg, etc.) The original William?s bullet also exhibited similar behavior being very tolerant of slower burning grades of black powder in tests at Springfield Armory during the US Civil War.

The tests showed that like the original William?s bullets the new style Williams bullet also needs to be lubricated. The Zinc washers in the original William?s bullets have a hardness of about BHN 30 and were able to easily scrap away the softer black powder fouling. The lubricant serves to soften the fouling and acts as a surfactant to allow the sharp edges of the bullet to wipe away the fouling. The NSW bullet does an excellent job of cleaning out the fouling when a soft lube is used. Tony Beck and I used MCM or MCM/Beeswax mixes for our test, whereas other testers used traditional Beeswax/Animal Fat mixes. The tests we performed indicate that over 100 rounds can be fired even with a slower burning black powder like Elephant with very little residue left in the bore with the last round going to the bottom of the barrel with the weight of the ram rod alone.

The prototype NSW bullet shot consistently in both constant and progressive depth barrels. It does very well in the twist range of 1-48" to 1-56", and gives excellent results in slow twists of 1-66" to 1-83". The tests did note that the slower rifling twists shot to the point of aim whereas rifling twists faster than 1-66" shot in the direction of the rifling. The test results seem to confirm US and French tests in the 1850?s indicating that a rifling twist of 1-60" is still enough to induce a twist caused bullet drift at 100 yards, but not be as accurate as faster 1-48" or 1-56" twists. The rifling twist induced drift is a phenomena known as a Magnus force predicted by Bernoulli's law. Bernoulli's law predicts that if a round body (bullet) rotates fast enough it develops a low pressure area on the side of the body the spin is moving in, i.e. a right hand barrel twist will create a low pressure area on the right side of the object moving pulling it to the right. The best results with the bullet are in slower traditional minie' twists such as 1-72".

I did a dimensional analysis of the NSW bullet that indicates that ballistically it is very close to the pointed swaged US 1855 58 caliber Minie? bullet not the "old style" or "new style" Lyman nose cast minie? bullet with a large nose flat. The typical ballistic coefficient of a Lyman New Style bullet is around 0.198. The NSW bullets' mean ballistic coefficient for transonic and sonic ranges (600 to 1100 feet per second) is 0.209 with a sectional density of 0.214. The US 1855 58 caliber regulation Minie? bullet ballistic coefficient for transonic and sonic ranges is 0.208 with a section density of 0.214. The reason for this is that while the US Minie? is heavier, the shape of the William?s bullet is much more efficient in the transonic range. One interesting fact is that all testers reported the NSW bullet has the same point of impact as the RCBS Hodgdon bullet at 100 yards.

Ballistic Radar Comparison Of the Drag of The 58 NSW

I can say the prototype new style William?s bullet are a success based on the above trials and tests. The only changes I made to the new style William?s production moulds is to slightly thicken the leading flanged edge of the bullet to improve castabilility, increase the size of the dished base, and deepen the fletching groove to allow the groove to function better. These moulds are currently in the test phase to be release in Jan 2004. The price of the New Style Williams mould will be $45 postage paid.

Additionally, as a favor to a good friend and the N-SSA I?m running the six cavity 54 caliber Mk III Wilkinson Improved Picket Bullet as a co-op mould. Co-op moulds are were I pass the mould on to the membership at my cost for a run of ten (10) units. The bullet runs around 0.541? as cast and is sizable to 0.531? so the mould is really suitable for 0.531? to 0.543?. This mould is made of aircraft grade aluminum, with steel alignment pins & guides (no steel to aluminum contact), and has a cam operated sprue plate.


The new style williams bullet moulds completely sold out and are very popular. The ten shot bullet group in my avatar is a off hand group shoot with new style williams bullets at 50 yards by a USIMLT shooter.  The Wilkinson Mk III mould mentioned above was successful beyond all expectations.  The 58 caliber version of the Wilkinson Mk III bullet was used by Ed Schneeman to win a Silver medal in the 100M Minie' competition at the 2006 World Muzzleloading championships in Bordeaux France, and won a gold in the 100M Gettysburg competition.  What's more amazing is Ed got a silver using a stock Zoli Zouave Remington 1863 and no special equipment against shooters with much more elaborate set-ups.  The 58 Wilkinson Mk III mould is now being made in a steel block, and sold by North East Trading Company.

GE 2007
"no amount of scientific knowledge will make a rifleman without practice."

Henry Wilkinson 1852 from "Observations (Theoretical And Practical) On Muskets, Rifles And Projectiles"

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