CASE PREPARATION


 


There are many wonderful books and articles available on the Internet which provide detailed instructions on how to properly prepare your cases for consistent and accurate reloading. Paul Matthews’ series of books on Black Powder Cartridge shooting and loading are an excellent source of information for all BPCR shooters.

In the following text I have tried to address items that you probably (for the most part) have not seen discussed in any of these series of books.

Problems With New Brass

In my opinion new brass is being sold too short to be useful in BPCR chambers. An example is a popular case manufacturer that makes:

• New .45-90 brass cases which should measure 2.4” that actually measure from 2.389” to 2.393” in length before fire forming, and

• New .45-100 brass cases which should measure 2.6” that actually measure 2.589” to 2.593”, with an occasional 2.595”.

It is also important to remember that you will loose .005” the first firing and an additional .005” on subsequent firings for a total of .010”, making the brass too short for the chamber in most rifles.

Have you ever noticed the lube ring on the mouth of your cases, especially in cold weather? It may be an indication that the case is too short for the chamber and the excess lube has now occupied that space.

Determining The Proper Length Cartridge Case For Your Rifle

You can get a pretty good idea of your chamber’s internal dimensions by gradually trimming down a case that’s too long to fit your chamber properly until the breech block closes without force, and the mouth of the case remains sharp and is not crimped in.

An example would be to use a .45-100 case gradually trimmed down to determine the proper length for a .45-90 chamber, or a .45-90 case trimmed down for a .45-70 chamber, prior to fire forming. This method is not as accurate as a chamber cast but we are trying to keep it simple for the new shooter.

Tight Chambers

Now I know some of you are saying, “Well -- I have a tight chamber and my brass does not loose .010” with successive firings”. That’s a good thing, but typically isn’t the case for the vast majority of BPCR shooters who are using off-the-shelf or mass produced BPCR rifles in which the chambers are cut with a factory reamer. Many of us either do not have or cannot afford custom-made rifles whose chambers have been cut with a custom reamer. Remember, this site is oriented toward the new BPCR Long Range shooter who is probably going to be using a non-custom rifle.

Case Re-Sizing

I don’t recommend re-sizing (straight wall) cases once they are fire-formed, either partial sizing with a full length die or using a neck only die. Strive to “index” your cases when fire-forming them by using a symbol (you could use a letter or star that is stamped on the back of the case) as an index mark. Insert the case into your chamber every time that you load a round with that index mark in the 12 o’clock position for the remainder of its useful life. By not re-sizing the case:

a) we are allowing the case to maintain the closest tolerance possible for the chamber in which it was fired,

b) we are eliminating the process of re-sizing the case and then expanding the neck to allow seating the bullet, which can alter the concentricity of the case/chamber relationship,

c) we are eliminating the need to use a seating die to place the bullet in the case, as the bullet can now be hand seated.

By re-sizing the case and expanding the neck, we also alter the shape of the case and increase the space between the sides of the case and the chamber walls. The whole idea of fire-forming is to get a case to fit your chamber. Assuming the case wall thickness is uniform, we would not want to change the concentricity of the case in relationship to the chamber.

Neck Tension

Those of you who are familiar with high power or modern reloading techniques for competition or hunting will recognize the term “neck tension”. Neck tension is the pressure exerted on the neck of the case in order to a) hold the bullet in place, and b) to get the proper ignition from the smokeless powder used in modern ammunition.

This is important with many modern repeating rifles which are magazine fed and where the overall length of the cartridge is critical for the firearm to operate and feed reliably.

Neck tension in the world of the Black Powder Cartridge shooter is much different. Paul Matthews presents an excellent discussion about neck tension in his latest book entitled “Black Powder, Pig Lead and Steel Silhouettes”. Chapter 9 is entitled “Neck Tension-How Little?”. Paul discusses a number of factors concerning the reasons for and against neck tension as it pertains to BPCR shooting

Based upon my experience, I prefer to use no neck tension when I reload for competition. I firmly believe that having no neck tension produces the most consistent ammunition possible because it is far easier to control no tension on the neck of the case than to control how much neck tension.

Neck Wall Thickness

As far as neck wall thickness is concerned, a variance of .0015 or less is a good number for which to shoot. I’m not going to get into neck turning or rim thickness uniforming at this time, but they are factors that do affect overall accuracy. New shooters should not be concerned with this element of reloading when there are so many other things that must be mastered first.

Chamfering The Case Mouth

The mouth of the case should also be chamfered to remove any ragged edges resulting from trimming the cases to a uniform length. I have recently begun using a 14-degree chamfering tool made by Lyman for use with modern VLD (Very Low Drag) bullets. I have found that this tool and the resulting 14 degree angle that it puts on the mouth of the case makes seating the flat base BPCR bullets that we use in Long Range BPCR easier to seat with virtually no likelihood of shaving off any lead from the bullet.

Case Cleaning

For years shooters have used various types of media (i.e. crushed walnut hulls, ground corn cobs, rice, etc…) to clean their cases (usually in a vibratory polisher) after shooting. Recently, ceramic media has revolutionized the process of straight wall case cleaning by eliminating the need for multiple cleaning passes while delivering superior results (i.e. cleaning the primer pocket).

I recommend using a rotary tumbler like the Thumbler’s Tumbler (available from Cabela’s) or the RCBS Sidewinder Tumbler for use with ceramic media. The ceramic media is combined with water and a cleaning solution following the supplier’s instructions. Tumbling your brass from 4-8 hours is usually all it takes, depending on the number of cases you place in the tumbler with the media and water solution.

Yes, some shooters use ceramic media in a vibratory polisher, but these units are generally not approved by their respective manufacturers for use with wet media. Using ceramic media in a vibratory polisher could create an electrical hazard if it develops a leak and ruins the motor, voiding the warranty.

Pre-Cleaning Cases

Although ceramic media does an outstanding job of cleaning BPCR cases, I would still recommend that you pre-clean your brass, using water and “Dawn” dishwashing detergent. I use a small nylon brush mounted in a BATTERY operated drill to remove the majority of the internal fouling before tumbling my cases in ceramic media. DO NOT USE A CONVENTIONAL ELECTRIC DRILL FOR THIS PURPOSE. DOING SO MAY RESULT IN AN ELECTRICAL SHOCK AND WILL DEFINITELY RUIN YOUR DAY!

By George Liotta

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