Bud wrote: "I have told my son and two close friends of this to assure after my passing that these W-W cases are separated. This was with the admonishment that enlarged flash holes raise pressure."
Bud,
Have you ever seen an actual test reported that showed that enlarged flash holes raise pressure? I have heard this conventional wisdom forever but have never heard of any proof. I know it's a reasonable theory just like a perfect 11 degree crown is needed but -------?
I don't want to hi-jack this thread. Maybe start another thread with a warning and a reference to proof. If this is actually true all CB shooters should know about the danger. On the other hand if there is nothing to it except a long life of being repeated we should know that too.
Possibly in Hatcher's Notebook, or another serious research book of that era, there was discussion of the development of the .30 US Army (.30-40 Krag) and pressures.
The .45-70 cartridge as a black powder loading was developed with a larger flash hole, .096 if I remember correctly, and initial work on the new .30 US Army used the same flash hole size. Pressure rapidly escalated with nitrocellulose powders and a way to control the back pressure on the primer cup and subsequently pressing the firing pin was desired. There was a combination of factors, 1) the powder must be stable from freezing Arctic to hot jungle climates, 2) the powder must be stable over long storage times, 3) the powder must not overheat and raise pressures in a hot chamber during rapid firing, and the primers must function in these same conditions. This lead to the mercuric primer used until the mid-fifties.
Also during this time the Ordnance men worked with flash hole size. The physical chemistry characteristics of the ignition pushing back the primer to the bolt face and exerted pressure on the firing pin area was studied. One choice was to shrink the hole size. Testing showed that the .080 flash hole worked best in testing for the above criteria. Larger meant more gas push back spreading pressure to the bolt face and smaller meant less uniform ignition. As with many things in life, the hole size was a compromise.
That's what I read in Hatcher's Notebook, I believe. There are also several books on producing ammunition that I read at that time which my friends had and I am not sure where were the articles on development of the .30 US Army. Post-divorce, I did not have the money to waste on a television and spent evenings reading firearms books.
My son and I both own Trapdoors with their weak actions. I shoot black powder cast bullet loads in my Sharps and Rolling Blocks, thus I use W-W brass with enlarged flash holes to assure only these loads can go in the Trapdoor.
I've been around several guns blown up at the range and do not desire this happening to me. Sticky cases on the hot Midwest summer days of my youth is as far as I want to go.
I can't state from my own experiments that this is true, I only know what I've read of other's experiments.
Farm boy from Illinois, living in the magical Pacific Northwest