Griffinroydonald said:
I have had split cases with the turkish 8mm in both bolt action rifle and the belt fed beast. I went to the yugo 8mm and the split cases went away. Local gunsmith examined cases and told me the splits may be due to the age of the cases and the brass becoming brittle with age. No adjustments were made to headspace on the belt fed and the splits just went away when ammo was changed. I do not run the cheap turkish ammo in the 1919 or the Mg-34, I save that for the bolt action German guns.
Bravo Griff and the best post on the subject so far. Now all you have to do is make The "Barrel Problem" Group understand these and a couple other factors relating to Split and Seperated Case and your work here is done.
Brass, the quality of the stock it was made from, age, storage and transportation all contribute to the longevity of of a Brass Cased Rd. Much the same can be said for Steel Cased Rds. to some degree also.
Brass will do well in a dry environment add moisture and some heat then dry it out and the Hydrogen and Oxygen contained in the water will have changed the composition of the brass somewhat. Now do it over and over again and walla you have weak brass. No PHd needed just 20/40 peepers and your going to see the transformation first hand.
Transportation also takes it toll and everyone has seen this everywhere they look. Take a well used machine handle that is in constant contact with human skin and you will see wear, or the ring on your finger, anything that is touched or rubbed. Now take a case of ammo that is say 30 years old packed in a container metal of other and encased in wood. Now add some type of propellent that has free movement within the case for it to move around at will. Does it abraid the case from within, well your skin did something to the handle and the ring what do you think?
Now lets look at the propellent in the casing, has all that movement, trucks, planes, ships, cranes, over the years of storage and movement within changed it in any way, you bet it has. Has it changed the Burn Rate due to the reduction in size of the structure of the propellent inside the round, only a fool would say NO.
So you have a completely different loading with increased pressures of the cartridge involved with a weakened case and you are still looking to the barrel as to the problem of your split and seperated cases. This Ain't Rocket Science Gentlemen Just Fact.