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Muzzle Loading Rifles Powder Charge Selection – Davide-Pedersoli


The correct powder charge for any muzzle loading rifle has to be selected after considering several important factors, as follows.

Condition of the gun. Genuine antique guns have steel which cannot be compared with modern alloys. The old steel was the best they could produce at the time but it is now known to contain quite a lot of impurities and inclusions which over a long time, cause internal weakness which can cause a serious failure or bursting of the barrel.

For this reason, an antique gun should first be inspected by a gunsmith who has actual knowledge and experience with such guns. Then the gun should only be fired using a reduced powder charge so as to keep internal pressures and stress at a minimum.

Powder strength. Different brands of black powder and production dates result in some powders being stronger or weaker than others. Also, the finer grain powders produce more pressure than the larger grain powders so the correct grain size should be used for each caliber of rifle.

Bullet weight. The weight of the ball or bullet affects the internal chamber pressure being produced. A powder charge which might be quite safe when used with a ball weighing say 150 grains, might cause dangerous pressures when used with a conical shape bullet weighing 400 grains. Because of this pressure change caused by the bullet weight, the antique guns are usually loaded only with their original weight round ball or conical shape bullets.

Barrel vibration. All barrels vibrate in some particular direction. To obtain best accuracy we want to have the bullet exit the muzzle when it is at the same vibration position. If a first shot exits when the muzzle is at say an extreme left side position and the second shot exits when the muzzle is at it's right side position, then of course the shots will be far apart on the target. Strong powder charges cause the most barrel vibration while with a smaller charge the barrel vibration is greatly reduced……producing much better accuracy in most cases.

Therefore, the shooter is advised to determine whether or not maximum power is required such as in hunting deer or other larger size game, or, can the job be done with a slower speed bullet having better accuracy.

Use a paper target to test the group size produced by each powder type, charge weight and bullet type. The results of such experimental tests are quite important and will clearly show just what works best in your particular gun.

Remember, whenever ANY one component is changed, it will also result in some change in the speed, accuracy or group size. Therefore, when you must change powders, bullets or any other part of the loading process you are advised to go once again to the paper target and learn what the change has done to your accuracy as well as sight settings.

Excessive powder charge. Although an excessive amount of powder will not burn as efficiently as does a proper size charge, it does increase the internal pressures created. Therefore, we advise not to exceed the maximum charge weights shown on the chart below in order to prevent dangerous pressures which might cause damage to the gun as well as possibly injury to the shooter or bystanders.

Learning what sounds good. When the proper amount of powder is being loaded, a round ball or conical bullet will reach the speed of sound (or higher) as it exits the muzzle and will produce a very clear and crisp CRACK sound because it is traveling at supersonic speeds. A heavy conical bullet may not leave the muzzle at the speed of sound so there may not be a sharp crack sound heard but instead you will hear a booming sound which is not like the supersonic crack sound.

The speed of sound varies according to altitude and other factors but from a practical standpoint it is approximately 1087 fps (feet per second.)

Maximum charge weight and smallest grain sizes to be used. Modern muzzle loading rifles made by the Davide Pedersoli company use the very strongest modern steel alloys and are safe with maximum powder charges but in order to provide a usable guide to what a maximum charge would be, we offer a simple chart below, which lists the MAXIMUM powder charge and FINEST permitted grain size for various calibers and for round ball and conical bullets.

NOTE: The powder grain SIZE shown is the smallest grain size to be used. Larger grain sizes can be used.

For .32 to .36 calibers, FFg produces the best accuracy. For .40 to .50 calibers, FFg or 1.5 Fg produces best accuracy. For .54 and larger calibers, 1.5 Fg or Fg produces best accuracy. Use of too small of grain size can raise pressure to a dangerous level. When using a bullet weighing less than the weight shown, do not increase the charge weight.

Remember that with all muzzle loading rifles ----- the bullet must be firmly against the powder charge and no air space or gap is ever permitted as barrel damage can occur. 

Caliber

Ball wt.

Charge wt.

Conical wt.

Charge wt.

.32

45 gr.

70 gr. FFFg

not used

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.35 &.36

65 gr.

70 gr. FFFg

125 gr.

70 gr. FFFg

.40 (1)

not used

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310-316 gr.

120 gr. FFg

.451 (1)

not used

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475-535 gr.

130 gr. FFg

.44 &.45

128 gr.

120 gr. FFFg 

325 gr.

120 gr. FFg

.50

182 gr.

120 gr. FFFg 

490 gr.

120 gr. FFg

.54

230 gr.

120 gr. FFFg 

530 gr.

120 gr. FFg

.58

275 gr.

100 gr. FFg 

565 gr.

90 gr. FFg

.69 & .75

500, 545gr.

120 gr. FFg

not used

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(1) Gibbs long range rifle


For Davide Pedersoli & Co.
Dick Trenk
Competition Events Coordinator

rev 9-04

 

ver.9/04