BPCR Guide: Load Development

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Written by: Dick Trenk

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There are at least three methods of load development which can bring you to a point where you have the most accurate loading for your rifle with a particular bullet.

The first method (along with general assembly steps and suggestions) will be described next.

Many black powder shooters weigh every charge but what appears to be more important is to have the same powder “height” or “volume” of SETTLED POWDER in the case prior powder compression and bullet seating. This is more critical with Fg grain size than with FFg and FFFg grain sizes.

Because your bullet may have many seating positions possible, the actual powder height cannot be specified but the following will explain what is required and for these reasons it is usually a waste of time asking other shooters for their “pet” loads. Their bullet, seating depth, powder lot, compression, wad type, lubricants and many other factors will NOT be the same which your gun will be using. Therefore trying to obtain the good results someone else obtained with a certain powder charge and bullet generally does not work too well.

1Determine how deep in the case the bullet will be seated. Most guns shoot best when the ogive of the bullet is in light contact with the rifling or backed off about .010″ to .200″. I suggest starting with your bullet in light contact with the rifling. Later repeat the steps with the bullet backed off the rifling contact by .010″ increments.
2Having determined where your bullet base will be inside the case (we will use .500″ as an example only) pour in the powder and tap the case 12 times to settle the powder completely.Twelve taps is what I use and seems to be a good choice. You can select a different number as long as you stick with it all the time.Add powder and perform the tapping until you have the powder settled .500″ below the case mouth.
3Dump out the powder charge and funnel it into a hand held brass adjustable powder measure such as used by muzzle loaders.Tap the measure a certain number of times (12 taps on the bench top seems to work well) and record that number. After fully settling the grains then slowly raise the sliding piston in the adjustable measure until the powder is level with the measure top and tighten up the lock screw. You have now established the size of the powder charge (in volume) which when dumped quickly into the brass case (and tapped the same number of times), will settle to .500″ below the case mouth. This is an “uncompressed charge” and because the adjustable measure can be refilled and tapped with the exact same number of taps each time, you can obtain good consistency in your powder charge volume. Depending upon the bullet seating depth the powder charge will vary per the instructions given above.Note that the hand held adjustable powder measures have grain markings on their body. These grain numbers grains of “water” and are not the same as the grains seen on scales so you will find that the amount of grains of powder seen in the measure will become a larger number when the powder is poured out and weighed on your scale.
To obtain a greater volume of powder charge inside the case, you can buy or make a “drop tube”.This consists of a copper tube fitting the case mouth (3/8″ tube for 45 caliber cases) flared to suit the inside case mouth diameter) about 30 inches tall with a brass or aluminum funnel attached at the top. Mount this on an “L” shaped wood stand in such a way that the empty case can be placed under the bottom of the tube and the tube lowered slightly into the case mouth.Powder is poured into the funnel slowly over approximately 5-8 seconds time. The long fall will compact the grains perfectly and allow much larger powder charges to be used than could be put into the case with a quick pour action. Not only will you be able to get more powder into the case but your accuracy will be improved due to the consistency of the powder compaction in the case.A charge dropped into the case this way will be packed quite densely but is NOT considered a compressed charge…yet.NOTE: once you have determined the best powder “volume” you can then use a powder measure such as the Lyman #55 or other hopper type dispenser to duplicate that charge volume and speed up your reloading operations. Remember that even with a drop tube attached to this type of powder dispenser, your charge in the case is considered to be not compressed.
5To protect the base of the bullet, most shooters place a card or plastic wad over the powder grains. This wad can be bought from commercial suppliers or punched out with a suitable arch punch. The wad must be a snug fit in the case neck where it will be finally located so remember that there is a slight taper in all cases. Make or buy wads which will be about .002-.004″ larger than the place they are going to occupy in the case. Use cardboard such as seen on the backs of tablets, milk cartons, plastic from containers or other sources which are made from high density or low density polyurethane material. Thickness of the wad can be from around .010″ up to .060″. The most popular thickness is .030″ as found in milk carton and tablet backing material. Commercially made wads are stamped from gasket material made from vegetable matter and are called “veggie wads.” Some wads are stamped from very hard card material such as is used for shotgun wads. The main problem seems to be getting the wad diameter to fit properly down in the case. Careful measurements or consultation with the wad maker should answer this question of wad diameter. It varies because gun chambers vary in size, allowing brass cases to expand to whatever the chamber size is.
6Having charged the case according to repeatable methods, you load up about 6-7 rounds which have the bullet in light contact with the rifling as stated in step #1. Fire 2-3 rounds to pre-foul the barrel, then fire 5 shots at a paper target and later record the horizontal and vertical spread of the bullet holes. Remember to either wipe out between each shot or use your blow tube the same way between each shot.Fire further 5 round test lots of development ammo which has the bullet backed off the rifling by .010″, .020 and .050″. You should see some change in group size on the target.Once you see what bullet seating position in the case the gun likes, then stick with that position and make tests using different powder charges, having about 2.0 grains difference between each charge. You will again see the rifle telling you what it likes best. Keep good written records of each load and target results.

More refined loadings can be tested using different primers, powders, bullets, lubricants, wads, powder compression and other changes. But…remember this one rule when working up the best load, and this rule is CHANGE ONLY ONE THING AT A TIME. If you change two things, you won’t know which one caused the result!

The first load development method described above covered more than just making up test loads but from all the steps listed you now will have a good idea of what is involved in load development. Next I will describe the second popular method used to find what works best in your rifle.

Method number two is the idea of the late Creighton Audette who was one of the top recognized BPCR experts.

  1. Load a series of test loads using a slightly smaller powder charge than you want to end up with. For each group of test loads (say 3 or 4 rounds in each) add a small amount of additional powder (about 1. 0 grain between test groups) until your last group has slightly more powder than you really need.
  2. Fire all these test loads at one paper target at 100 yards without changing sights or the way you bench the rifle or hold it. Try for consistency in every shot.
  3. Due to the increased powder charge in each test group, you should see the bullets hitting the target in a rising manner as recoil increases. Using a good spotting scope, plot your shots on an unused target and identify each lot clearly.
  4. You will notice that some groups tend to clump together “vertically” more closely than other groups and some groups spread out more than the others.
  5. The bullet groups which struck the target more closely together left the barrel as it had vibrated to near the end of its movement and was nearly stationary at that moment. The bullet groups which impacted the target making a larger group size left the barrel when it was still moving.
  6. Chose a loading from among the groups which stayed closest together.

The third and final method of working up the best load is as follows.

  1. Load up about 20 rounds and put your strongest powder charge in the first one while making each one thereafter having 0. 3 grains LESS powder.
  2. Fire them at one target starting with the WEAKEST loading.
  3. Record on a clean target, the impact point for each shot.
  4. As you get into the stronger powder charges your bullet holes will climb upwards on the target but the rise will NOT be uniform. Some shots will clump together and others will spread apart.
  5. Those shots which clumped together (even if their powder charges were quite different) represent bullets which left the barrel while the barrel was at its extreme vibration point (as mentioned in method 2 above).
  6. Pick a load which is in the middle of one of the powder charge ranges that produced a small bullet hole spread and load up at least 5 or 10 using the exact same methods.
  7. Fire these loads making every effort for consistency in how you bench the rifle and hold it.
  8. If you can duplicate the small group size originally produced, you have hit upon “one” of the loadings which your rifle likes and which will minimize inaccuracy caused by barrel vibrations.
  9. If you seem satisfied with your test load, now is the time to refine it even more by making ONE CHANGE at a time to primer, powder, compression, bullet alloy, lubricants etc. etc.


The powder charge dumped quickly into the case or, the charge poured slowly down a drop tube, or powder dispensed from a hopper type powder measure, is considered to be “uncompressed”. What you have after use of a long drop tube or the use of a vibration device, is a “settled” powder charge not a compressed charge.

All black powders respond for better or worse, when additional compression is applied. By far, the usual result of applying additional compression results in improvement to both accuracy and velocity. Sometimes you will also find lower barrel fouling as well.

Experimentation is required to determine what your powder likes best.

Match grade ammunition should always be compressed using a special “powder compression die”. Using the bullet seating operation to compress the powder strongly may deform the soft bullet ogive in a manner so slight as to be unseen by your eyes, resulting in inaccuracy and possible jamming in the chamber.

You may find best speed or accuracy is obtained using an uncompressed charge or that compression as high a .300″ produces better results. Due to grain crushing effect with excessive powder compression, it is not recommended to compress black powder more than .300″. (Note that when duplicating 45-70 original military type ammunition used in Springfield Trapdoor models, very high amounts of compression is required. This should not be done for non-military type reloading in Trapdoor and other types of BP rifles. )


As mentioned above, bullets and wads must be in actual contact with the settled or compressed powder charge. If a significant amount of air space is present between powder and bullet, a dangerous pressure spike may occur which can “ring the chamber” or cause other forms of damage including personal injury.

Experts are not in agreement about this “chamber ringing” problem but to stay on the safe side I am advising not to allow more than 1/16″ of air space between powder and wad or powder and bullet base.

Never intentionally load a small amount of black powder into a case which would create an unfilled air space larger than this distance.