Case Cleaning and Preperation

Case Preparation

Before you start to reload you need to get your cases ready. This involves depriming, cleaning, resizing and primer pocket preparation.

Case Cleaning

When a bullet is fired the case is coated with a fine layer of powder residue on the inside and to a certain extend the outside of the case. The primer pocket in particular gets very dirty and needs to be cleaned to ensure consistent results.

Ultrasonic cleaners can be used to clean a deprimed case as it cleans not only the cae but also the powder pocket. The cleaning medium can consist of just water but better results can be achieved with a mild acid solution. People use vinegar, citric acid or even denture cleaners. You will normally need three 8 minute cycles to clean the case. Do not overload the cleaner and try a few different regimes to decide what cleans your cases the best. Ultrasonic cleaners do not polish the brass.

Once clean, rinse the cases and if using vinegar it is worth putting in a solution of bicarb to neutralise the acid. The cases can be air dried or have warm air forced through them with a hair dryer.


Tumblers use a medium such as coconut husk or corn cob to gently clean and polish the cases. Its very important to ensure when you take your cases out you tap them or blow air through to remove ALL the cleaning medium. If you are going to use a tumbler then its normally best to leave the primer in till the cases are clean.

When starting out you might not have an ultrasonic cleaner or tumbler. You can put your cases in a pan of very hot water and citric acid then agitate the cases to help remove the dirt. Its worth rinsing and clean again to get as much residue off as possible, Once clean rinse and dry the same way as the ultrasonic cleaner.

There are three different types of cases: New you have purchased, fired (hopefully just once) in someone else's rifle or fired in your rifle.

New Cases

Shouldn't really need to do anything, but you should check length just in case and trim if required. You can full length resize but they really shouldn't need it. If you have a primer pocket uniformer then you can use this to ensure the pocket is perfect. It is not essential.

Fired (not your rifle) need full length resizing

You can clean your cases before resizing, and if using a tumbler this is a very good idea as the cleaning media doesn't clog up the primer pocket and flash hole. Cleaning the cases before sizing means the dies remain nice and clean.

The cases will need to be full length resized so they fit in your rifle chamber. Lube either individually using a cotton bud or several at a time on a lube mat. Lube the neck, making sure there is no lube on the shoulder as this can lead to denting the case. Insert the case in the shell holder and cycle the press which removes the primer and resizes the case back to standard dimensions. Wipe the lube of the cases with a paper towel.

Once deprimed you can either clean the primer pocket with a pocket cleaner or use an ultrasonic cleaner. If you have a primer pocket uniformer then you can use this to ensure the pocket is perfect. It is not essential.

Once fired (your rifle) just need neck sizing

As they have been fired in your rifle then they should fit your chamber perfectly. If shooting straight-pull 5.56mm AR15 type rifles then it is recommended that you full size your cases each time. For normal bolt action rifles all you need to do is neck size them.

As with full length resizing you can clean the cases before neck resizing. Neck sizing doesn't usually require the necks to be lubed, but check your instructions that come with the dies. Insert the case in the shell holder and cycle the press which removes the primer and resizes the case back to standard dimensions.

Its a good idea to just “pop” the primer out and not do the neck sizing at the moment. This way if you haven't already cleaned the case it does not coat the inside of the resizing die with powder residue from the case. The case can then be cleaned, if not already.

Once deprimed and cleaned you can do the neck size. Load the case into the shell holder and cycle the press. If using Lee dies then its very important you press hard at the bottom of the stroke and “feel” the case neck being squeezed slightly. Then rotate the case 90o and resize again to help maintain consistency. If when loading the case later you find the neck does not grip the bullet well then you have not pushed hard enough on the handle. Consistent neck tension is one of the most important things to get right for tight groups when shooting.

Trimming the Brass

Check with your reloading manual for the maximum length of your brass. If yours measures more than about 10 thou less than the maximum then trim it back to 10 thou less than the maximum. Ideally all your brass should be the same length.

To trim the brass use either a hand-held trimmer or one of the many desk mounted devices. Lee do a zip trim that holds the brass tightly whilst you put in a spigot for your calibre into a handle that precisely measures and cuts the brass to the correct length. Lyman have a lathe type device with a handle to again precisely cut the brass.

After trimming use a chamfering tool to chamfer and deburr inside and outside of case necks.

Your cases are now clean, deprimed, trimmed and ready to load.

Author Andy