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#9
10-21-2008, 07:18 PM
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Quote:
Here is a post from another site which explains it for you. "bear9963780, You have received some good info here. The belt has to do with headspacing, only. Most belted cartridges don't actually need the belt to establish safe headspacing, but new unfired belted cases are headspaced off the belt, nonetheless. To get a better grasp of the advice you are getting here, it would help if you knew more about headspacing. Technically, it is the distance between the bolt face and the case head. When a belted case is chambered and the front of the case's belt is in contact with the correlating belt portion of the chamber, the case is prevented from moving any further forward. The distance between the case head and bolt face is the headspace. When a nonbelted case is chambered and the shoulder of the case is in contact with the correlating shoulder of the chamber, the headspace is, again, the distance between the case head and the bolt face. Handloaders can ignore the belt when reloading a fireformed belted case and treat it as if it was nonbelted. Here is where the problem comes in. Most factory rifles chambered for belted cartridges have some tolerance between the case shoulder and the shoulder of the chamber. This space is in addition to the headspace, and some chambers are generous than others. It seems that most factory chamberings for belted magnums tend to be generous. Of course, it is within SAAMI specs and is safe for a first firing, but it can be problematic for the reloader. The firing pin drives the case forward, but it is slammed back into the bolt face when the powder starts burning. The headspace is gone and the brass must stretch to fill a larger cavity. The more it stretches to fit, the thinner the brass gets just ahead of the belt. When you hear of case head separation, this is where it occurs. Many belted cases can be reloaded several times. Unfortunately, I have also witnessed case head separation on only the second firing. It just depends on how generous your chamber is. A good indicator that the brass is getting dangerously thin at the expansion ring is the appearance of a thin bright line just ahead of the belt. A prudent handloader will check fired belted cases with a tool (a bent paper clip will work) to feel inside the case for signs of a problem. A good friend of mine was starting to experience case head separation on reloads in his 300 WinMag. His headspace was safe enough for a first firing, but not for subsequent reloads. For chambers like this, having a gunsmith fix the headspace issue should be the first item on the agenda if you want to continue firing reloaded cartridges in such a rifle. Short of that, necking up new brass to 8mm or .338 and necking back down incrementally to .308 will form a false shoulder to eliminate headspace issues from overly stretching brass, an the cases will last much longer. If you want to get into handloading, acquire as many loading manuals as you can reasonably afford. If only one manual is in the budget, start with the manual from the bullet maker of your choice. All manuals have good information about handloading. Lyman's is a good neutral choice since they do not sell bullets or powder. I'll get off my horse now. Good luck. -------------------- Regards, Sam Taylor NRA Life Member NAHC Life Member SST's Rifle Room http://www.angelfire.com/mo2/rifleroom/" 
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