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Gday fellas, unsual find today whilst running cases through the lee zip trim setup, with the 7-08 pin an cutter in place all good there was about 6 or so that were BENT, or Wonky from the case base and wobbled around pretty 'full on' , whereas the other 65 were mickey mouse straight as.
Can someome elaborate on this- i will assume the case grew and just went one way more than the other...
safe to use- if it chambers? accuracy not the biggest drama for me- i miss 2 out of 7 every time anyway
I have a Lee case trimmer like below for every caliber cartridge I have as backups for my Lyman trimmer.
Many times the Lee trimmer lets the case wobble in its jaws and I just rotate the case until the wobble is almost gone.
My AR15 rifles really chew up the case rims and cause the most wobble when trimming the cases.
The only time the case can actually wobble is if the case is thinner on one side and warps when fired. And is more pronounced with skinny cases fired in larger diameter chambers.
And again if you have a runout gauge this shows up as a egg shaped case body and the base of the case no longer 90 degrees to the axis of the bore or case head squareness.
Neco Concentricity, Wall Thickness and Runout Gauge
The NECO, patented, Case Gauge is the most versatile instrument available for measuring the various accuracy determining factors of cartridge cases, bullets and loaded ammunition. No other gauge can measure all of the following: 1.Banana curvature of case. 2.Wall and neck thickness variations. 3.Case head squareness. 4.Banana curvature and out-of-round shape of individual bullets. 5.Runout of seated bullet. 6.Total runout of loaded cartridge. The "Case Gauge" can be used to measure cartridges from .17 cal to .50BMG by purchasing the appropriate "chord anvil".
Biped, its the same sort of tools but the top one goes into the little lee zip trim spinner- thats why i notice which is bent or not.
interesting, thanks for the info, it could be fair to say that cases may have stretched in places and since firing has bent them from that point.
il keep an eye on this--- especially after this lot of firings- once they r done. could be a while
When the cases warp you may see bigger groups, but with .002 to .003 shoulder bump you have an air space between the base of the case and the bolt face. This reduces the effect of the case head squareness because the ejector and firing pin push the case forward in the chamber. And full length resizing with .002 to .003 shoulder bump will reduce any effects of warped cases.
Below your shoulder bump amount will be your head clearance on a chambered round. One of my favorite humorous saying about full length resizing is, "The cartridge should fit the chamber like a rat turd in a violin case."
Below Kevin Thomas worked in the Sierra ballistic test lab before shooting professionally for LAPUA USA.
