View Full Version : Corrosive primers: why clean the bolt face?

Ignition Override
January 25, 2010, 01:01 AM
If the primers all stay in place, how does enough primer 'salt' get into the action or hit the bolt face?
Where else in the action should these rifles be wiped with a wet patch (and dried)?

The latest rifle is my first Mauser (48A), also a LE #4 and two #5s.
Have used corrosive ammo for two years, with no visible damage, and mostly clean just the bores with Windex or hot water/dry, and wipe/dry the bolt faces.

Just now having read about complex cleaning procedures on the M48 section of "Surplusrifle", and have read numerous other tedious methods. Have become a hard-core fan of certain classic military rifles, and nothing else.

January 25, 2010, 02:23 AM
a certain amount of blowback, comes back aound the cartridge case in the often generous chamber of an old military rifle....hense you neutralize the salts that possibley made it back into the action, and on things with a bayonet -you clean the bayonet as well (even if folded when fired ,say on a Mosin M44) and underbarrel cleaning rod.
I use the hot water/ windex on some things...GI WW2 Corrosive bore cleaner on others(its toxic and not real good for ya)
But lately i fianally tried Ballistol "sportsman's oil", its what the German Army developed and used in WW1 and WW2 for all thier corrosive ammo...it smells good and non toxic...mix 50/50 with water to clean out the bore salt, and straight as a gun oil.

January 25, 2010, 04:49 AM
Corrosive priming has, as one of its important ingredients, potassium perchlorate which, after firing, leaves a residue in the bore known as potassium chloride. This is the first cousin of sodium chloride, aka table salt.

It's not actually the salt that causes corrosion; Salts are what is known as hygroscopic, i.e. they attract/absorb moisture. It is the moisture that combines with the steel in your barrel and forms iron oxide, aka rust. (If you lived in a fictional world with absolute 0.000% humidity, your bore would never rust.)

Basically, all is needed to remove this salt residue is ordinary water. Hot water works better and hot soapy water works best. Windex works because it is a water based product. (And convenient to carry.)

Ignition Override
January 25, 2010, 02:00 PM
Thanks for the complete description.
Always head straight home for cleaning.

F. Guffey
January 25, 2010, 05:00 PM
Cleaning the bolt face. Primers when fired unseat when the case is blown forward by the primer, THEN, the case head moves to the rear and re-seats it against the bolt face, hot high pressure metal cutting gas can escape and deposit the corrosive material on the bolt face, This will be identified by a circle that is the same diameter as the primer.

Other accounts claim the bullet, case, powder and primer accelerates to a speed equal to or greater than the firing pin in an attempt to escape the firing pin strike, on my rifles the primer is crushed before the rest of the case knows it has been hit. Reloaders that use the companion tool to press, the feeler gage, can cut down on case travel and reduce case travel when firing and sizing.

PSI being equeal in all directions and the flash hole having a diameter small tham the primer serves as a restrictor, the primer is blown back and the case is blown forward, I am a big fan of cutting down on all that travel, case and primer.

F. Guffey

F. Guffey
January 25, 2010, 05:02 PM

Sorry about that,

F. Guffey

James K
January 25, 2010, 10:34 PM
Gas can escape around the primer and that gas can contain primer residue. Also, corrosive salts can escape from the fired case when it is extracted from the chamber, and get into the action. While this seldom results in such obvious damage as a rusted bore, it is a good reason to clean the breech face and action as well as the barrel when shooting corrosive primers.