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CASE PREPARATON FOR RE-LOADING TECHNIQUES FOR YOUR COMPASS LAKE ENGINEERING UPPER OR BARREL

The purpose of this information is to share our technique for producing reliable and consistent brass for reloading. We want to ensure that your reloaded ammunition successfully makes it into your chamber and that your fired cases extract. Be aware, this is specific to gas guns. There are differences between procedures for bolt guns and gas guns.

I have been reloading ammunition for 53 years and for the past 30 years my focus has been primarily on reloading for high-power competition. Bench rest techniques will not be detailed here, so there will be no information on turning case necks. Ammunition loaded for 600+ yards may require additional prep, deburring flash holes, etc., depending upon your brass. We will walk through the process of how we do it and offer some tips on things to look for in your procedures. I am sure there are other ways to accomplish reloading, but this is how we do it.

First, decap your fired cases. This will enable you to thoroughly clean the cartridge case, both inside and out, including the primer pocket. This is a good opportunity to inspect your cases for defects such as neck splits. We then clean the brass using a stainless-steel pin tumbler – follow the instructions for your tumbler. We tumble it for about one and one-half (1 ½) hours, although it may run slightly longer if your brass is very dirty. Using the separator supplied with your tumbler, we separate the brass from the pins. Dry the brass after separating it from the pins.

There are two (2) important dimensions that need to be maintained while sizing your cases.

(1) THE BODY DIAMETER OF THE CASE.

This is established by the dimensions of your sizing die. It should not be necessary to use a small base die when sizing the brass for our chamber, but it is an option and doesn’t hurt anything. If you are using brass that you pick up at the range, I recommend that you use a small base die the first time through. After that, your standard die should work okay. Most standard sizing dies do a good job, although some competition dies are designed for bolt guns rather than gas guns and these may not adequately size your cases for a gas gun. Even good dies that have been in service for years may not size your cases properly, so please consider how many barrels those dies have loaded ammo for. Dies wear too, as well as the chamber in your barrel. A die that loaded great ammo for your old barrel may not work for your new barrel with a new chamber. Whenever you get a new barrel, test several of your sized cases and make sure that they fall easily into the chamber and fall back out. If there is any doubt about the fit, I recommend that you get a new Lake City cartridge case and see how it fits. The only cure for sized cases that don’t freely go into the chamber and come back out is a new sizing die. We have had very good luck with Dillon carbide dies, but there are others that work just fine. Please read our information PREPPING BRASS FOR A GAS GUN VS. A BOLT GUN at the end of this.

(2) THE HEADSPACE DIMENSION OF THE CARTRIDGE CASE.

A new Compass Lake Engineering barrel and bolt has the headspace adjusted somewhere in the bottom one-third (1/3) of the tolerance zone. The difference between GO and NO GO is only .003”. You want your sized case to have a headspace dimension that does not exceed the length of a GO gauge. This will ensure that the bolt closes easily on your loaded ammo. We highly recommend that you use an accurate method to measure the headspace of your sized cases. There are different ways to accomplish this measurement. You can use a commercially available case micrometer (mic) and make sure that it is on “0” or .001” or .002” less. We also manufacture and sell a Chamber Gauge that enables you to get an accurate headspace reading using a dial caliper. WITH THE UPPER RECEIVER REMOVED FROM THE LOWER RECEIVER, you can also try sized cases in your gun. You can drop the case into the chamber and close the bolt carrier with your thumb. Start with your sizing die backed out slightly, and screw it in until the bolt closes on the sized case. You may want to compare your case with a new factory case. This method works, but it does not tell you what the variation is on the headspace of your sized cases.

Considerations for the sizing process. The MOST important thing is for you to size your brass on a very rigid, single station, press. There may be a progressive press available that will work, but I haven’t found it yet. The more flex in the press, the greater the variation in the headspace dimension of your cases. Another advantage of the carbide die is very low friction, which will result in further variation in the headspace. You should strive for no more than .002” variation in headspace with the maximum not exceeding zero on your case mic.

Lubricating your brass

We use RCBS Case Lube 2 or possibly another water-soluble case lube. We dilute it about 5:1 with 100% denatured alcohol and put it into a spray bottle. Different lubricating techniques will work. We have found the quickest and most consistent method is to put approximately 100 cases at the time into a gallon plastic freezer bag and spray several pumps from the spray bottle in the bag. Seal it and squeegee the brass around to coat them evenly and then dump them onto a clean cookie sheet. Let them dry for five (5) minutes.

You are now ready to start sizing your brass. Most sizing die instructions I’ve seen call for screwing the die down until you hit the shell holder with ram all the way up. This is a good starting point, but it will deliver over-length headspace due to the spring in even a rigid press. Size a case, measure the headspace, and then screw the die in a little at the time until your dimension is correct. Do ten (10) more and check your variation. If some exceed the max, screw the die in a little bit more. At this setting the shell holder will bump the bottom of the die fairly hard. NOTE: This applies to steel dies. A properly adjusted carbide die should not be hit with the shell holder.

Clean your brass again by running it through the stainless pin tumbler for 30 minutes or so. The use of the water-soluble case lube will insure that there is no lubricant left on the cases when you are done. You can dry the cases by laying them out on a towel for maybe a day. Be sure that your brass is very dry when you start to reload it. Check the overall length of the cartridge case and trim and deburr if necessary. We use a Giraud Case Trimmer (http://www.giraudtool.com/prod02.htm) and trim 100% of the cases.

Following these procedures will result in cases that are the proper dimension and also clean and ready to load. With two (2) exceptions.

(1) If you have military brass that had crimped in primers. The crimp needs to be removed. You can perform this operation after you decap. Alternatively, you can purchase a Dillon 1050 and it will take the primer pocket crimp out as you load your ammo.

(2) If you insist on using walnut shells or corncob media to clean your cases, you must wash and dry your brass before reloading. Otherwise, you run the risk of leaving abrasive dust in the cartridge case, which will result in premature wear of your barrel. We have seen very expensive barrels shot out in 1,500 rounds due to abrasive wear from the dust left in the cartridge cases. You can wash the brass in the sink with hot water and dish detergent. Tumble the brass around a few times to wash them, rinse them, and set them out to dry. My hope is that this information, although it is lengthy, will help you load ammo for your new rifle efficiently, properly, and safely. I want you to enjoy your new barrel and for it to last you many rounds downrange.

Frank White
Owner
Compass Lake Engineering

COMPASS LAKE ENGINEERING THE DIFFERENCES IN CASE PREP FOR GAS GUNS VS. BOLT GUNS

As someone who has caught cases being extracted from a bolt gun, I can tell you they are not very hot. As one who has desperately tried to remove a cartridge case that came out of a gas gun from between my shooting glove and the back of my hand, I can tell you, they are HOT. This is the major reason why you must have more clearance between the cartridge case in the chamber in a gas gun.

In a typical .223 or .308 service rifle, the bullet clears the gas port approximately one-thousandth (.001) of a second after the firing pin hits the primer. The bullet clears the muzzle in another 5 thousandths of a second, about 3 or 4 thousandths of a second later the bolt starts to unlock. The cartridge case has been exposed to fifty thousand + pounds (50,000) pressure of very, very hot gas that has absorbed a lot of heat. Assuming a final temperature of 400 degrees, the case on a .223 has expanded almost .002”. If there is no initial clearance between the case and the chamber, you are pretty much guaranteed a failure to extract. In fact, in my experience, 99% of failures to extract are due to either very dirty chamber or oversized brass.

The same cartridge case fit in a bolt gun causes no problems because you cannot open the bolt fast enough before the brass transfers its heat to the chamber walls and shrinks back down close to its original size. Neck sizing is not a good idea for a bolt gun and definitely should not be done for a gas gun. Doing so will make you the guy at the range trying to knock your cases out of the chamber with a cleaning rod.




This product was added to our catalog on Monday 28 August, 2017.