In case you don't know, Elmer Keith was the dean of American handgun experts from the mid-20's until his death in 1984. He's given credit for the origin of the .44 Magnum cartridge. Elmer was just about the greatest advocate for big bores and big heavy bullets in rifles as well as handguns who ever lived, considering the .30/'06 barely adequate for shooting jackrabbits!

Prior to WWII, Keith and two of his associates Donald S. Hopkins and Charlie O'Neal, designed several wildcat rifle cartridges called the OKH (.280 OKH, .333 OKH and .334 OKH) series, and in these they also experimented with front igniton such as you have described. The .333 OKH is the direct predecessor of the .338/'06, and the .334 OKH is identical to the .338 Win. Mag., except for a .005" difference in bullet diameter!!

When Keith worked at Ogden Arsenal in Utah during WWII, he persuaded the Army Ordnance boys to test his front ignition ideas in the .50 BMG case. The conclusion was that while front ignition did permit higher velocities with less powder and pressures, it was not worth the extra effort needed to install the flash tubes and load the powder charges evenly around the tubes. So the idea was not pursued further by the Army.

Another person who played around with front ignition was "Rocky" Gibbs, designer of the Gibbs sereis of wildcat cartridges based on the .30/'06 case with the shoulders blown out and forward leaving a 0.25" case neck to hold the bullet.

Back in 1991, Wolfe Publishing Co. printed a booklet written by Roger Stowers entitled "GIBBS CARTRIDGES and Front Ignition Loading Technique. This gives about as much info as there is on this subject, and perhaps more than anyone would really care to know about it, since it is totally impractical for most people who reload ammo! However, the book is interesting for the descriptiopns of Gibbs' cartridges and the loading data given for all of them from the .240 Gibbs through the .338 Gibbs (the ultimate .338/'06 for sure!!).