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4.5 inch howitzer reloading suggestions

W

WDHaskins

New Member
Greetings from Oklahoma. We have a 1916 4.5 British howitzer, apparently imported in to the U.S. for development of 40 m/m Bofors rounds as it came with barrel insert to fire those as well. Fully functional, has WWII modification with pneumatic tires. We have a mold and have cast projectiles, but it takes 37 lbs. of lead to do, when we're firing projectiles much easier to simply shoot the Bofors rounds as we have many projectiles. But I digress.

We mostly fire the gun in our Boy Scout Troop flag ceremonies (Troop One, Tulsa, Oklahoma, chartered in 1910). Shoot blank loads. Have been using 155 howitzer powder loaded over a black powder bag using a 50 cal. primer for ignition. The howitzer powder may be going bad, not sure, but blank loads are giving erratic ignition. Embarrassing when she only gives a "pop" and the powder flies out the end of the barrel burning but not exploding.

Could load blank loads with black powder only, would take about 1 1/2 lb, but hate to use that much corrosive in such a finely machined mechanism. Could load some ANFO with the howitzer powder, but don't know anything about the pressure curve of ANFO or whether in a blank load, without projectile, it is even a concern. Is there anyone out there who has any ideas of what load to load in a blank round to safely make the Boy Scouts (and me) happy with a proper report? Would PETN out of det cord be a better substitute than ANFO to "bridge the gap" between getting the black powder to detonate the 155 howitzer powder rather than burn it? Don't know pressure curves on PETN either. I'm thinking the fact that the blank load has no compression of a projectile raising the pressures is what is causing the howitzer powder to burn rather than explode. Have an explosives license, so the ANFO or PETN are options, or maybe a better explosive than either?

Thoughts?
 
Welcome to the forum. Your lucky to have such a toy to play with. As for your question, only my thoughts, a black powder load with a smokeless powder top would throw the smokeless powder out before it burn off properly as the black powder would burn much quicker. Have you mixed the black powder and smokeless howitzer powder together so you have an even mix, this I suspect would leave no after burn. Most blanks do have a seal/crimp or some form of compression to create the sonic bang ie a thick cardboard disc sealed with silicone bead, plus it gives that short space of time for a complete burn. Have you also tried a better primer than a .50cal primer or a much hotter primer. As for using explosives in a barrel you could get erosion marks inside the chamber, I suspect most would advise not to use explosives. There are guys in this country who use black powder in their tanks and 25 pounders plus a paraffin bag to give that film effect which is used in the pyro film industry so its safe to use by the experts.
 
Never heard of the paraffin bag, and the idea of mixing the black throughout the 155 howitzer powder is a good one. This gun still balances using the mere push of a finger on the elevation wheels after nearly 100 years, and I just am trying to avoid the black powder corrosion issues. What is the "paraffin bag", and where does it insert in the load, and what does it do? Thanks for the response.
 
The paraffin bag gives more of an effect of smoke, a smoke ring etc, basically they fill up a latex glove with paraffin on top of the charge, don't use diesel as it doesn't burn off properly, you can find all about this on the web under special effects. As for corrosion issues you will only get that if your primers are corrosive, its actually the primers that cause the corrosion especially the old type, use modern ones. Your still have to clean out the bore with hot water as black powder residue is water soluble, oil solvent wont remove it, used the oil to dispense the moisture like WD40 afterwards. I suspect old .50cal primers WW2 stock would give you this problem.
 
Never consider the use of High Explosives inside a metal container as a solution for making noise or propelling anything! That means no ANFO, PETN, TNT, RDX, Dynamite, Blasting Caps (Detonators), or anything that detonates instead of burns. High Explosives hold the highest concentration of energy next to nuclear. You don't want energy, you want smoke, flash, and noise.

That being said, the first thing you need to do, is to enlist the help of someone that is knowledgeable in reloading pistol or shotgun and rifle cartridges, because they should know something about the burning rates of different types of Low Explosives (Smokeless and Black Powder). Low Explosives burn or deflagrate at a subsonic velocity less than 3300 FPS whereas High Explosives Detonate at a supersonic velocity from 3300 FPS to more than 28,000 FPS. School boy experimentation with combinations of energetic materials is more likely to cause damage to your gun that lead to a proper mixture, and the use of low pressure 50 cal primers in a high pressure gun can lead to destruction of the firing mechanism when the primer gets blown into it.

I would hate to think what the ATF would have to say about the use of High Explosives in a public environment for unapproved activities.
 
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