can't google it. and i've seen only spent casings for 105mm guns during ROTC. what i'm talking about is whether or not ww2 guns and cannon cartridges had slim steel tubes brazed at the base, covering the flash hole from the primer pocket. the purpose is to transmit the primer flash deep into the propellant charge. igniting the charge near the middle, instead of at the base, is supposed to allow more complete burning and reduce chamber pressures significantly. that means you can gob more powder into a cartridge with little danger of exceeding prescribed pressure limits. in the case of the 105, there's a tube from the primer flash hole that extends barely an inch into the propellant charge.

a gun writer, elmer keith, claims to have discovered the advantages of this with magnum hunting rifles. normally, slow-burning magnum charges take a lot of barrel length to burn (you can actually see particles of unburned powder exit the muzzle.) so he and a friend soldered a slim steel tubes into the casings so as to ignite the charge 1/3 up, instead of at the base. they submitted their findings to the US army, which couldn't adopt it into their field guns (so said keith,) but they were instructed to keep it secret, lest the germans use it to improve their 88s.

Mac,

Don't hold me to this, going 60 years and them some, but, 105's had a primer tube that ran about 2/3's the length of the case, that would be 10 or 12 inches.

__________________
All the Best
Jack

you're talking about the m-119 or 102? the ones i've handled were m-101s (ROTC way back.) if the primer tubes were that long, then they must disintegrate upon firing.

all the same, was this technology used in ww2?

Yes. I have a British 4.5" (introduced prior to WW2) naval cartridge case which has such a tube (a thick brass one) running about three-quarters of the way up the case. I also have data pages on US ammunition which shows such extended primers on every fixed-case round above 40mm used in WW2. In the smaller calibres the primers only extend about a quarter of the way up the case, but in the bigger ones they go most of the way up.

They don't disintegrate on firing; my 4.5" case has been fired.

Edit to add; on reflection, the principle of these flash tubes is slightly different in that they have perforations all the way up, being intended to ignite more of the propellant.

__________________
Tony Williams: Military gun and ammunition website