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Spray-On Case Resizing Lube

Update - 100% Synthetic Motor Oil

The ongoing research has determined that the very best case lube for bottle neck rifle brass is 100% synthetic motor oil.  Castrol Syntec 5W20 works very well, but other viscosities would probably work well too, as would the full synthetic (not synthetic blends) from other manufacturers such as Mobile-1 or Amsoil.

  1. Pour 1/8" of full synthetic motor oil into the cap.
  2. Dip the case neck, so the oil coats the open end of the case neck approximately 1/8" on the inside and outside of the neck.  It's important to lubricate the inside of the case neck so the expander rod won't stick or drag so much that the brass is stretched and work hardened which would soon result in case neck splits.
  3. Use your finger to wipe the oil off the outside of the case neck, which will leave a very thin film on the outer case neck.  Wipe that oil down the outside of the brass.  Avoid case lube on the shoulder (the angled portion of the brass below the case neck and above the body) because oil on the shoulder can result in hydraulic dents on the shoulder.  Hydraulic dents are caused when the resizing die pushes the incompressible oil into the brass.  Hydraulic dents will be pushed back out when the round is fired but will result in work hardening the brass and shortening its life.
  4. Resize the brass.
  5. Tumble the brass after resizing to remove the resizing lube and clean inside the primer pocket, prior to reloading.

The advantages of 100% synthetic motor oil:
  • Very inexpensive.  $5 per quart for a lifetime supply.
  • Readily available at auto parts stores and automotive sections of department stores.
  • Fast - smaller calibers need lubrication only every 10th case!
  • Easy to use.
  • Not as messy as sprays and sticky waxy lubes.
  • A small amount is needed, so it lasts longer and doesn't gunk up the tumble cleaning media.
  • Extremely effective.  Demonstrated repeatedly lubricating only every 20th .223 case! The only lubricant that allowed resizing oversized .50 BMG brass that had been fired in a loose chambered machine gun.

I made a video demonstrating the use of 100% synthetic motor oil as case lube.


The case lubricant portion starts four minutes and thirty seconds into the .223 case prep video.

I still use the spray on case lube described below to lubricate straight wall pistol brass.

Spray-On Case LubeHomemade Spray On Case Lube

Lubricating cases can be the messiest and one of the most time consuming processes when reloading rifle brass, but you don't dare try to full length resize without case lube or you'll have the frustration of a stuck case.

After experimenting with many different methods, the spray-on case lube seems the best to mist onto pistol brass to ma.

  • Fast
  • Easy
  • Inexpensive
  • No strong odor, so it can be used indoors
  • Powder safe & primer safe


First, you'll need a spray bottle.  Almost any spray bottle will do.  Many household cleaning products use spray bottles that you could reuse, or you can buy a plant mister spray bottle from Walmart, Lowes, Home Depot, or a local nursery.

Simply add two 2 ounce tubes of Lee Case Sizing Lubricant to the spray bottle, and one 16 ounce bottle of 91% isopropyl alcohol.  The alcohol can be used to rinse out the last bit of case lube from the tubes.  Isopropyl alcohol is readily available at pharmacies, or in the pharmacy aisle of Walmart or large grocery stores.  Shake well before screwing on the spray head to avoid a big glob of undissolved case lube plugging up the siphon tube.

Rifle Brass

Hornady makes a good universal loading block for this application.  Place the loading block on a cookie sheet.  Arrange the brass in the case loading block, neck up.  The head of the brass should be inside the case block to keep case lube out of the extractor rim, but the rest of the case should be exposed.  Shake the case lube to mix well before each application.  Spray a fine mist to evenly coat each case.  The cases should appear evenly misted, but there should be no liquid dripping down the sides.  Spray downward at a 45 degree angle so some of the case lube enters the neck because the inside of the neck will be sized as well as the outside of the case.  The case lube is completely powder safe and primer safe, so a little case lube inside the case will not be a problem.  This isn't true of oil based case lube.  The cookie sheet should completely contain the over spray.  Rotate the loading block 90 degrees and repeat the process, a total of four times to ensure the brass is coated on all sides.  Allow the brass to dry completely.  Overnight drying is easiest, but brass will usually dry in about an hour.  Placing the brass in front of a fan will reduce the drying time to ten minutes or less.  The lubricated brass should have a uniform cloudy appearance and a slightly waxy feel.

Rifle Case Lube AnimationSpray-on case lube is fast and easy, and it keeps the case lube off your fingers, but there is a messy wax over spray.  About half of the lube is sprayed onto the load blocks and cookie sheet.  It's possible to recycle this case lube if you keep the load blocks and cookie sheet clean between case lubing sessions.  Place the load blocks on the cookie sheet and dowse with isopropyl alcohol.  Use a soft bristle brush to agitate the alcohol and dissolve the waxy case lube.  Pour the alcohol into the spray bottle of case lube and add one tube of Lee Case Sizing Lubricant.

Case lube can be removed with a vibratory bowl cleaner before the primers are inserted, or the case lube can be removed with an alcohol dampened towel after loading.  The Lee Zip Trim and a ScotchBrite pad can also be used to polish the brass after loading.  Reloaded ammunition should not be cleaned in a vibratory bowl cleaner or tumbler because the powder can break down into smaller granules or the burn rate moderator can be abraded off the powder granules, resulting in a faster burn rate and possibly a dangerous overpressure.

Pistol Brass
Pistol Brass - Drying
Straight walled pistol brass doesn't need to be lubricated when using a carbide resizing die, but it's very easy to lubricate pistol brass and it greatly reduces the force needed to resize the brass, making the reloading press operate much more easily.  Mist the inside of a clean plastic food storage container with case lube and dump in the brass.  Very little case lube is needed for pistol brass.  Place to cover on the container and tumble the brass around for a few seconds to evenly distribute the case lube and pour the brass onto a cookie sheet to dry for a few minutes.  The container is sprayed instead of the brass to keep the case lube out of the inside of the cases.  It won't hurt anything if sprayed inside the cases, but it doesn't help anything, either.  If you're in a hurry and don't mind a slight waxy residue on your fingers, you can reload the pistol brass immediately after misting with case lube.  Pistol brass needs only a slight mist of case lube.  It should have a barely fogged appearance when dry, with about 10% of the case lube of rifle brass.  Apply only enough that the cases start to look a little dull instead of shiny.  If they look waxy or cloudy, you used too much and the cases should be cleaned after resizing, which is a hassle and isn't consistent with high speed progressive pistol reloading.  If you the correct amount, there is no need to clean the small amount of case lube from the pistol brass before shooting.


Do not fire brass without removing the case lube.  The spray on case lube will oxidize under heat and pressure to form a black goo resembling waxy tar that will prevent the cases from ejecting properly and might build up enough in the shoulder area at the front of the chamber and prevent the cartridge from chambering properly, which may result in a firearm firing slightly out of battery.  The sticky residue can result in stuck cases, and possibly a chipped or broken extractor.

Lubricated cases using any type of lube, including especially synthetic motor oil, can also result in excessive pressure on the bolt face because the lubricated case will tend to slide backward as the chamber pressure increases. Unlubricated cases expand against the chamber wall and temporarily stick there.

Spray-on case lube is flammable.  Isopropyl alcohol can be ignited by a spark or open flame.  Be careful to avoid all ignition sources when using this or any other spray-on case lubricant.


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