Powder Ignition Failure

[Bruce_in_Oz]

One thing to note is that the old Lebel case is quite "fat".

Thus, any "lightish" load will settle below the centre-line of the case and thus below the flash-hole alignment.

With some powders, this "primer flash-over" is a recipe for a spectacular detonation. With others, you may get a hang-fire, or at best, the primer will JUST drive the bullet into the throat where it will stick, and the powder will be partly "melted" into a blob.

The old "Lebel" round was derived from similar black-powder cartridges of the era; see also include the 8mm Guedes / Kropatschek.

In those, one could jam in a fair swag of the old charcoal and get reliable ignition.

The early French powders were probably developed for loading by "bulk", not weight., i.e., an early "Pyrodex".

In BOTH cases, one must ask one important question:

"Was the case "fully formed" before insertion of the propellant or, as was the case (so to speak) with Cordite, the bundles inserted into a parallel-sided case BEFORE final neck-forming?"

The Brits' answer to the French introduction, was good-old "Cordite". The original .303 ammo had a PELLET of BP inserted before final forming and this method continued with the "smokeless" ammunition. The VERY first "trials" cartridge cases did not even have a "properly" formed shoulder and neck, but a weird "collar" that was a straight lift from an experimental Swiss cartridge.

The original primers were also different to those used today in "commercial" ammo.

Note that The .303 originally used a BOXER primer. Boxer was British and his system worked.

HOWEVER, when smokeless became all the rage, there was a sudden change to a BIG, chlorate-rich primer having two TINY, offset flash-holes. This set-up provided TWO jets of ignition flame into the back of the Cordite column. The Chlorates, sulphur etc in these primers provided a "flash" of greater endurance, this being necessary to ignite the new propellant.

Note that several of the other military cartridges of the same era also used "LARGE" primers in the 0.250" size range. Primer technology and chemistry were comparatively new fields at the time. Nitro-Cellulose propellants were likewise new and were noted to be MUCH harder to get started than tried and true Black Powder.

Style-wise, the Americans had become keen on the British-developed "Boxer" system, mainly because of its ease of reloading, back in the 1870s. Interestingly, in the 1930s, they made up a special batch of .30-06 "match" ammo that used BERDAN primers, SPECIFICALLY because this system seemed to give more consistent combustion, and thus, better grouping, than the Boxer-primed equivalent.

As for "recipes"; the US Ordnance System was slow to adopt the lead-based primer. However, commercial suppliers quickly cottoned-on to the fact that lead-based primers were an absolute boon to their reloading customers. The lead-based primer was a German innovation from before WW1, and was described (in German), in various technical publications of the time. They had also done a substantial amount of research into the corrosion issue as well.

Despite all of this study, ALL military ammo, EVERYWHERE was also CORROSIVE until WW2. The kick along came from the US introduction of the .30 M1 Carbine, with its "non-user-serviceable" gas system. Pretty much ANY genuine military ammo loaded before about 1950 (apart from M-1 Carbine) WILL be made with corrosive (chlorate-rich) primers.

The 7.62 NATO was the FIRST post-WW2 cartridge SPECIFIED from day one, to be "non-corrosive". Most "Eastern-bloc" SERVICE ammo is STILL fitted with CORROSIVE, lead-based primers; they are designed to go BANG first time, EVERY time.

The French were loading spectacularly corrosive .30-06 ammo, with both brass and STEEL cases, well into the early 1960s.

[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...!

[browningautorifle]

I've seen .308 fired in 30-06 chambers. They fired fine and fire formed to the long chamber nicely. They had no support there at all. They had enough primer and powder to do the job. You're lacking in both. I have other examples too... And I understand your bona fides.

[bombdoc]

I've seen .308 fired in 30-06 chambers. They fired fine and fire formed to the long chamber nicely. They had no support there at all. They had enough primer and powder to do the job. You're lacking in both. I have other examples too... And I understand your bona fides.

Thanks Jim...

I will up the loading and see what happens!

[browningautorifle]

Keep us infoed...

[CINDERS]

FWIW Go up in .2's of a grain up to max and see where you get, some cases only really work when they are loaded up besides you may strike another node point and get an even tighter grouping also trying another powder is not a bad thing I have loads for 4 different powders (Thank goodness for excel spreadsheets) for each of my centrefires as when one supply dwindles you can swap to another and carry on. Means more range time and reloading but hell that's what it is all about, still reckon crimping may not be a bad thing JAT

[Bruce_in_Oz]

Many years ago I was warned about "low" loads in pistol cases.

The one that got a bit of publicity in pistol-shooting circles was:

2.7 grains of "Bullseye" behind a 148gn Wadcutter in a .38spl case. This was reputed to potentially take your nice K-38 apart without a screwdriver.

I recall that the H. P. White lab had done some looking into this matter.

Bullseye is one of the fastest powders ever offered on the commercial market and was designed for light loads in small cases.

2.7 grains of the stuff barely forms a film on the bottom of the case. A "flashover" means that the whole lot ignites ALMOST instantaneously, as opposed to damn fast. Explosion vs. VERY rapid burn. The resultant SHOCK is what makes your K-38 look shabby.

"Low" loads mean that there is a lot of space NOT occupied by the propellant. Variations on how the propellant is "arranged" at each shot will lead to variations in ignition and thus pressure curve, and, ultimately, down-range performance.

This applies at ALL variations of "partly full", but is MUCH less noticeable as "full" density is approached.

Some years ago I was fooling around with some .223 Rem loads and getting odd pressure signs but reasonable accuracy. A mate was over one day and I raised the matter. He looked at me "funny" and said he was using the same cases, powder and bullet as I was, BUT using MORE of the same powder, in fact, a slightly compressed load. I gave it a whirl and he was right; one grain more than my most recent trial produced smaller groups AND did not display the serious primer flattening of the marginally "lighter" loads. Voodoo stuff indeed.

[Ex Crab]

Many years ago I was warned about "low" loads in pistol cases.

The one that got a bit of publicity in pistol-shooting circles was:

2.7 grains of "Bullseye" behind a 148gn Wadcutter in a .38spl case. This was reputed to potentially take your nice K-38 apart without a screwdriver.

I recall that the H. P. White lab had done some looking into this matter.

Bullseye is one of the fastest powders ever offered on the commercial market and was designed for light loads in small cases.

2.7 grains of the stuff barely forms a film on the bottom of the case. A "flashover" means that the whole lot ignites ALMOST instantaneously, as opposed to damn fast. Explosion vs. VERY rapid burn. The resultant SHOCK is what makes your K-38 look shabby.

"Low" loads mean that there is a lot of space NOT occupied by the propellant. Variations on how the propellant is "arranged" at each shot will lead to variations in ignition and thus pressure curve, and, ultimately, down-range performance.

This applies at ALL variations of "partly full", but is MUCH less noticeable as "full" density is approached.

Some years ago I was fooling around with some .223 Rem loads and getting odd pressure signs but reasonable accuracy. A mate was over one day and I raised the matter. He looked at me "funny" and said he was using the same cases, powder and bullet as I was, BUT using MORE of the same powder, in fact, a slightly compressed load. I gave it a whirl and he was right; one grain more than my most recent trial produced smaller groups AND did not display the serious primer flattening of the marginally "lighter" loads. Voodoo stuff indeed.

According to the on line loading data from Alliant, 3grns of Bullseye is the max load behind a 148 grn HBWC. I've used as little as 2.5 grns without any problems. I now use 2.3 grns N310 in 38 Spl, still no problems.

[bombdoc]

Ok.. sorry to not to have been back on the board for some time..

I have been doing some further trials on the Lebel loading and have increased it (by stages) to 44gn. The ignition problems appear to have gone and there are no overpressure signs.. groupings are good for an old gun!

I must admit to being surprised by such a "step" in the performance with a less than 10% change causing such a difference! I'm not at all clear as to what is happening here. N140 is not a particularly slow powder and the original 39.5gn load filled over 2/3 of the case, so the flash from the primer must have impinged on the powder.. so why did it not ignite?

Having examined the unfired powder it is clear that the primer has blown off the powder coating yet there is no evidence of ignition..!

Strange.. I will remain careful with this loading but the extra few grains seems to have sorted it!

Thanks for all the advice chaps..!

[Eaglelord17]

You could possibly be seating the primer too deep. I had to pull 50 7.7x58 Jap rounds when I first started reloading because using the hand primer I was squeezing them too far in and it wasn't igniting the powder properly because of that. My solution was to stop using the hand primer (instead using the press) and the problem went away.