Underdog Posted June 15, 2014 Report Share Posted June 15, 2014 After sizing some 357mag cases these cracks showed up! So I photo'd them to show anyone starting out what to look for. Some cartridges can suffer from this more than others, Hornet and 303 are favourites but I have seen some 222 start too (probably due to me winding it up etc.). Anyway..... Underdog. Quote Link to comment Share on other sites More sharing options...
kent Posted June 15, 2014 Report Share Posted June 15, 2014 I actually take a small homemade pick at the internals of hornet cases as well as visual inspection. I have had zero incidents of this in up to ten re-loads, using lilGun and a well cut chamber I think its largely a thing of the past but still I check. Worthwhile picture to show mind Quote Link to comment Share on other sites More sharing options...
rem708 Posted June 15, 2014 Report Share Posted June 15, 2014 This is due to full length sizing. When full length sizing the shoulder flows up into the neck. When the cartridge is fired the case expands and grips the walls of the receiver but also pushes back on the bolt face. The stretching occurs at the weakest point in the case which is where the cracks appear. If you have to FL size then back it off till a point where the case fits the chamber and the bolt closes without binding. The other side effect with the migration of metal is the need to constantly trim the case Personally I neck size and only rarely FL size hence I don't have any of these issues. Quote Link to comment Share on other sites More sharing options...
kent Posted June 15, 2014 Report Share Posted June 15, 2014 This is due to full length sizing. When full length sizing the shoulder flows up into the neck. When the cartridge is fired the case expands and grips the walls of the receiver but also pushes back on the bolt face. The stretching occurs at the weakest point in the case which is where the cracks appear. If you have to FL size then back it off till a point where the case fits the chamber and the bolt closes without binding. The other side effect with the migration of metal is the need to constantly trim the case Personally I neck size and only rarely FL size hence I don't have any of these issues. And with a straight wall case like the 357 shown that headspaces on the rim? Quote Link to comment Share on other sites More sharing options...
rem708 Posted June 15, 2014 Report Share Posted June 15, 2014 I was just about to correct my posting :-) I personally have never had this on a straight case. I have loaded magnum cases over and above standard pressures for use in a Thompson Contender pistol but I hardly used any crimp as it was a single shot. My standard round for a .44 mag was a jacketed 240gn bullet with a MV of 1640fps - powder was Hercules 2400 (now Alliant). 6 shots was about the max I could take because it punished my hand so much. The same frame with a .223 barrel was a pussy cat in comparison. I used to retire the cases once the primmer started falling out. Never once did I get stretch. Interesting - do you polish your cases? My mentors in the US warned me not to over polish (I took no notice ) as it apparently it puts higher forces on the bolt face. If the case is not so slick it could be gripping the receiver in the same way as as bottle nose do thus causing elongation. Certainly heavy crimping does this (case expands significantly before releasing the bullet! Quote Link to comment Share on other sites More sharing options...
Imperfection Posted June 15, 2014 Report Share Posted June 15, 2014 Yep,i've twice had case head seperation with 357,but they had been reloaded many many times. Quote Link to comment Share on other sites More sharing options...
Underdog Posted June 15, 2014 Author Report Share Posted June 15, 2014 Good points fellers, these cases and their history are un-know to me, apart from these being binned the rest will be fired once and ejected to the never never. I do think (all be it un-scientific) that full power loads are kinder to brass than softer loads, I simply base this on how the brass grabs the chamber to maybe just clinging on! Just a hunch that's all. I wonder know what would happen if I just sized half a case! U. Quote Link to comment Share on other sites More sharing options...
kent Posted June 16, 2014 Report Share Posted June 16, 2014 I think a lot depends on a lot of things. top of the list is quality of the brass second the chamber / headspace dimensions, if you consider this and stick to std charges and inspect you will normally do just fine without over thinking things Quote Link to comment Share on other sites More sharing options...
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