Powder Ignition Failure

[bombdoc]

Hi,

Thanks for the input chaps. To respond to the various recent posts...

I have not found many loadings for the Lebel.. and none for Vit Powders. My loading is derived from the 8x57 recipe in the Vit manual which suggests 39.5 of N140 for a 180gn bullet and 42.7 for a 200gn one. I have done stairsteps firing trials and the 42gn charge appeared to give the best approximation to the service load. My choice of N140 is based on availability and where it sits in the burning rate table. It is generally considered to be a suitable powder for medium calibre rifles, which this is...

For those not in the know, the Lebel case is probably the most conical of all the early smokeless cases, going from 1/2" down to 3/8" in about 1.5". The 42gn charge comes to about 1/4" below the base of the neck so is not IMHO excessively low and is well above the flash hole alignment..

The Lebel was the world's first military smokeless powder cartridge and used an early single based nitrocellulose "poudre blanc" propellent. The main issue with the round was as a result of adopting a spitzer bullet in a tube magazine! The base of the case had to have all sorts of catch rings and double primer covers to stop the rounds initiating in the tube..! I only ever load these single shot! The Lebel was designed as a smokeless round from day 1 and was fully formed before loading.

As to primers.. from what I understand, the main shift was from fulminate of mercury to lead azide because of stability issues in storage. Chlorides were used in both mixtures and caused bores to rot if not cleaned.. the combination of mercury and chloride residue would eat a barrel as you watched! True "non corrosive" primers did not come in until after the war with styphnate based compounds. As I said before, I'm not convinced this is a primer problem as I am using a modern powder/primer combination that should ignite under these conditions..

Thank you again for your input.. although I have a lowly headstamp on this board, I have been at this game for over forty years both as a shooter of old guns and as an Army Ammunition Technical Officer (check with Peter L for my Bona Fides..).

I am curious about what I am seeing here, and would like to get to the root of it! I know about the "bear at the back of the cave" issue with low and slow loadings - this may be related...

My theory is that the weak neck tension and probable worn throat is causing a condition akin to a low density load in that the initial pressure pulse is blowing out the bullet into the bore and increasing the size of the apparent chamber. The rapid increase in volume is dropping the pressure to the point where, for some reason, the propellant is not igniting! I just think this is odd as the pressure in the chamber should not be affecting the primer performance - at least I have never seen this reported in the literature...!