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Developing Loads for Muzzle Loading Shotguns (Part 1)

posted May 20, 2010, 3:45 PM by Peter Lucas   [ updated Dec 17, 2012, 9:22 AM ]
  Developing a load for your muzzle loading shotgun requires some time and effort.  Unlike a modern shotgun, you can not simply put a "standard" load in your muzzle loading shotgun and assume that you are going to get an acceptable pattern.  If you are going to shoot a muzzle loading shotgun, you are going to have to spend some time at the patterning board.

    If you are reading this article, I assume that you already have a basic understanding of how to load a muzzle loading shotgun.  (The Circle Fly Wads web page has good basic information on loading a ML Shotgun.) I am going to skip over the basic instructions on how to load the gun and instead focus on the issues related to down range performance.  There are a number of different factors which impact on quality of pattern produced by a muzzle loading shotgun in any given gun.  These factors include: (1)  the type, quality and amount powder, (2) the type and number of wads placed over the powder charge,  (3) the volume and size of shot, (4) the use of a shot cup,  (5) the type of over-shot wad, and (6) the choke of the gun. When developing a load for a muzzle loading shotgun, experience dictates that there is one simple rule:  Each load must be patterned for each individual gun.  In applying this rule it is important to keep in mind that any component in the load can affect the results in a good or bad way, and several combinations should be tried until the optimum load is for the particular gun in question is determined.

    The two most important variables are amounts of powder and shot.  Fortunately, the amount of powder and shot are also the two variables which are the easiest to change and experiment with.  They also have the greatest effect on the performance of the gun.  The time honored rule of thumb for the starting place for a load is simple: Use the same volume of powder and shot. Application of this rule is easily accomplished by using the same measure to load both shot and powder. It should go without saying that the equal volume rule is based on the volume of shot and powder and not weight.  By weight, the proper powder charge for a one ounce load of shot is approximately 68 grains of black powder.

   Equal volumes of powder and shot produce excellent light loads with either 1 or 1 1/8 ounces of shot in a 12 gauge gun.  The 2 1/2 dram load (68 grains) with one ounce of shot can produce close to 1100 fps with the right gun and wad combination.  Rady Dyer, the current NMLRA national muzzle loading skeet champion, uses equal volumes of shot and powder with shot payloads of between 3/4 and 1 ounce (depending on the gun which he is using).   Rady's shooting proves that light loads will break birds on the skeet range, assuming that you do your part.

     Equal volume loads also tend to produce good patterns, even in in cylinder bore guns.   Using one ounce of shot and an equal volume of powder,  my cylinder bore gun will place approximately 55% of the pellets in a 30 inch circle at 40 yards.  This equates to a modern improved cylinder pattern.  For most clay target shooting, the one ounce load produces perfectly acceptable velocities and patterns (assuming that you have the proper choke for trap shooting).   In my view there is not much reason to move beyond an equal volume load for target shooting. 

    In addition, if you get a chance to chronograph your load, you just might be surprised by the velocities which the equal volume loads will produce in some guns.  I have a Underhammer Trap Gun which has a 33 inch barrel.  Using a 1 ounce load with 2.5 drams (68 grains) of Goex FFg, that gun will produce average velocities of 1141 feet per second.  With a 1 1/8 ounce load with 2.75 drams (75 grains) of Goex FFg, the gun will produce average velocities of 1152 fps. 

    After selecting the powder and shot charges to be used as a starting point, the next step is select the wad combination.  Generally, the over the powder wad combination will start with a 1/8 inch nitro card.

    Next a lubricated "cushion" wad is used and sometimes a thin over shot wad on top of the cushion wad. The term "cushion" wad is a little bit of a misnomer.  Cushion wads are generally soaked in vegetable oil or a similar liquid prior to use.  The primary purpose of the lubricated cushion wad is not to "cushion" the shot, but instead to lubricate the bore and keep the black powder fowling under control.  The biggest draw back to oil soaked cushion wads is that they are messy.  If you are using a lubricated cushion wad, your hands are going to get oily from handling cushion wads.  When you combine oil hands with black powder residue, you will start smearing black stuff all over everything you touch.

    Some shooters will place a thin over shot wad on top of the cushion wad to avoid having any of the shot column stick to the top of the cushion wad.  Kim Davis, a former NMLRA National Trap Champion, indicates that he started using an over the shot wad above the cushion wad after recovering a number of the cushion wads at the patterning board.  Each of the cushion wads had a number of pellets stuck to the top of the wad.  Pellets stuck to the top of the cushion wad obviously do not break birds. 

    Many shooters forgo the cushion wad and use a 1/8 inch nitro card as their only over the powder wad.  Similarly, some shooters will simply use two thin over shot cards above the powder charge.  V.M. Starr, the famous muzzle loading shotgun gunsmith was an advocate of this wad column.  Without the lubricated cushion wad you will run into is the accumulation of fowling in the bore.  V.R, Starr would spit down the bore after the over the powder wads had been rammed home.  Spitting down the bore raise a number of issues.  Instead, many shooter simply spray a small amount of water mixed with Murphy's oil soap down the bore after the over the powder wad is rammed home. 

    By using either lubricated cushion wads or spraying the water/soap mix down the bore, you can go several hundred shots over a period of days without cleaning the bore. 

    The final wad component is the over the shot wad.  Virtually all shooters use a thin cardboard over the shot wad.  However, in my view, not all over the shot wads are created equal. There is a significant variation among the brands of wads. The difference relates how well the over the shot wads seal the bore.  Sealing the bore with the over the shot wads is not really a good thing.  The over the powder wads create an air tight seal at the bottom of the bore.  If an air tight over the shot card is used, it become difficult to ram the over the shot card home because of the volume of air which has to be displaced.  In fact, beginning in approximately 1840 "dented over shot wads" began to appear.  The dented wads had small triangular shaped dents along the edges of the over the shot wads.  The purpose of the dents was allow air to freely escape as the over the shot wad was rammed home.

    Unfortunately, none of the modern manufactures make dented wads, so we are stuck using round over shot wads.  In my experience, Circle Fly over the shot wads tend to be stiffer and create more of an air tight seal.  This makes them a little harder to load.  Other brands of over the shot wads tend to be lighter in weight and do not seal the bore as well when they are rammed homes.  This makes them a little easier to load.  However, if you are hunting the thinner over the shot wads may not hold the charge in place as well as the stiffer wads.  Personally, I use the Circle Fly wads when hunting and the thinner wads at the range.

    You are now ready to take the gun to the patterning board.  If you are shooting an "equal volume load", there is a good chance that your gun will pattern will regardless of the wad column which you select.  If you get an good pattern with equal volumes of shot and powder and are just planning on shooting clay targets, your work is done.

    While the equal volume rule has its place, the limitations of the equal volumes rule need to be recognized. In my view, the equal volume rule will not produce an adequate "heavy" or hunting loads with 1 1/4 ounces or more of shot.  The equal volume rule would indicate that 1 1/4 ounce of shot should be propelled with 3 drams (82 grains) of black powder.    Depending on your gun and wad combination, this load will produce a velocity of between 900 and 1000 fps.   From my experience these velocities are not adequate when hunting larger upland birds, such as grouse, chuckars and pheasants.  These velocities are clearly inadequate for anything but the shortest of shots when hunting waterfowl with steel shot. 

    When developing a heavier hunting load, the trick is to find a load which produces both good patterns and higher velocities.   That will be the subject of Part Two. 

Equal Volumes of Shot and Powder by Weight

Black Powder
Black Powder
 12 1/2
 1 1/8
 2 3/4
 1 1/4
 1 3/8
 3 1/4
 1 1/2
 3 1/2

Note: always stay below the maximum safe load for your particular gun.

Sample Velocities Using the Equal Volume Rule

Black Powder
 1 68 1090
 1 1/8
 75 1000
 1 1/4
 82 920
 1 3/8
 89 890

Sample velocities using Goex FFG in a twelve gauge shotgun.