onondaga
posted this
01 January 2013
http://www.castbulletassoc.org/view_user.php?id=61>mike morrison:
I can add to the answers you have gotten so far. Powder selection and charge volume is the most predictable cause if your primers have no more power than standard primers as the manufacturer claims. Please verify that as it could be the principle cause of your hang-fires.
Firing pins either explode a primer compound or they don't and then the result is only a misfire if the primer doesn't explode. Primer compound detonates, it does not burn like gun powder-- there is no halfway fizzle with detonation compounds in primers to cause a hang-fire. However some specific, severe primer contamination can chemically change the detonation compound into a propellant that burns but doesn't explode after percussion of the compound by the firing pin. That specific chemical contamination is very rare.
The explosion of a primer does the same as any other explosive. It blasts a high speed shock-wave and fire.
The charge in the cartridge case has to be compatible with the explosion of the primer to light. There is a balance that causes good dependable charge lighting that can be disturbed. Specific charges that are effected by the shock-wave in a form of turbulence that keeps the charge of propellant from lighting is possible. Specific charges can experience a turbulence that delays ignition of the propellant. Light charges with excessive airspace in the case have the highest potential for this type of hang-fire.
If your charge is filling 80% of the case or more with a recommended charge weight and recommended powder the shock-wave turbulence type of hang-fires are very rare.
If your volume is good and the charge/powder is a recommended one but you are still getting hang-fires, contamination of many types will do this or weather combined with leaky primer seal or leaky bullet seal allowing moisture or chemical condensation contaminating your powder is the cause.
If you are using a low volume, fast burning pistol type propellant, you can have hang-fire even with a recommended charge when your primer is not matched to the job as recommended. Magnum primers used to light tiny charges cause misfire and hang fire. This is why they are not recommended for lighting tiny charges. The shock-wave turbulence is too extreme. A magnum primer can also push the bullet down the bore before an imbalanced charge even has a chance to light. This can make a rifle act less like a rifle and more like a pipe bomb.
You can also get a hang-fire if there is insufficient pressure during ignition to completely light the charge. This is commonly caused by using propellants with lower burn rate than recommended propellants or propellants at the bottom or top of recommended charges that are at the low end of burn rate propellants that are recommended. You can upset the balance of ignition as lots of loaders are very aware.
Sometimes a heavier bullet or a tighter crimp will compensate and repair the balance with slower powders, Sometimes fillers will too. Sometimes you get hurt or your rifle does. Powder manufacturers and bullet manufacturers recommendations are to protect you, your firearms and their profits from being lost in court. So, they are very serious are about their recommendations.
Gary