Strange brass...

[44Blam]

Saw some brass this weekend where there was a tube that screwed into where the primer sat and funnelled the primer blast up and back toward the powder.

It was about a 1 1/2" tube into what looked like a 30-06 case... Anyone seen anything like this?

[JimB..]

There was a discussion about these in another thread a month or so back, unfortunately it was a tangent and I don’t recall the original topic. Maybe something about position sensitive powders.

The consensus was, as I recall, that with the right load the tubes do slightly improve accuracy, but generally just not worth the effort. Concept may have been an adaptation from artillery rounds, and maybe folks were playing with this in rifle rounds in the late 1960’s, I just don’t remember the discussion that well other than to think it’d be kinda cool to run across some one day.

[Bent Ramrod]

Elmer Keith worked out a system he called “Duplex Loading” (to confuse enemy spies in WWII) that had a tube in the flash hole directing the primer flash to the top of the powder column in the case.

This would burn the powder charge from the top down, letting only the gases drive up the barrel behind the bullet. Normal ignition allows the gases to drive the powder granules up into the barrel, with more irregular ignition of the granules and erosion up in the bore. Keith claimed much lower velocity spreads and a significant increase in barrel life.

Cases set up like that would be hard to manufacture in quantity and very expensive. Reloading setups that wouldn’t mangle such tubes to uselessness would be difficult to design. So it wasn’t practical for small arms ammunition, even if it did work.

[Kraschenbirn]

Can't dredge up the trade name but I recall similar brass being touted in a couple of the gun rags back in the early 1960s. Manufacturer made some really "interesting" claims for higher velocities and improved accuracy but no one seemed to be able to duplicate the advertised numbers. Ran a black & white ad in the back pages of Guns and Ammo IIRC.

Bill

[Tom W.]

I remember reading about them with duplex or even triplex ( is that a word?) loads a looooong time ago. The supposedly harder to ignite powder went in first, then the easier to ignite powders went in last where the fire from the primer was directed....

[adcoch1]

From other threads on the topic I gathered that it was done to uniform a pressure curve by keeping the powder column in the case, and therefore producing a more consistent and repeatable burn. If I remember correctly the idea was kicked around and attempted by some benchrest and other guys forever ago, and works great. But it required a complicated deprime and reprime process, so it fell by the wayside..

[JSnover]

I believe it was called a front ignition tube.

[stubshaft]

Oneil Keith Hopkins = OKH were involved in designing cases that lit the charge from the front of the case.

[Wayne Smith]

Oneil Keith Hopkins = OKH were involved in designing cases that lit the charge from the front of the case.

Yup, and the idea was taken from an artillery shell. Not that the results were worth the effort.

[beagle]

This system was used with the .50 Spotter/Tracer round by the Army in the 106 Recoilless system. This round was loaded with IMR 7383 powder as I recall which is a fairly slow burner. Whether it was used because of more reliable powder ignition or to ignite the tracer element I don't know but they worked pretty well. We used the .50 rifle to simulate rocket firing on the AH-1G Cobra helicopter in the late 60s. Worked pretty well but the round was pressure sensitive and adjustments for proper functioning on the ground were unreliable at altitude. Had an adjustable system for tapping gas for functioning./beagle

[44Blam]

Cool. Interesting stuff.

A friend of mine showed me a few of those and my first thought was "wow, that would be a PITA to deal with" but he maintained that they found them in an estate sale from a guy that was a competitive shooter. He said that it allowed for much better accuracy and higher velocity. Thinking about it, it seems like you would end up with lower chamber pressures and probably a cleaner burn at the lower pressure...

[Grapeshot]

Elmer Keith wrote of this in "Hell, I Was There!" IIRC he was writing about .50 caliber BMG rounds. This setup gave higher velocity and lower breech pressure. Three inch, 75/76mm, 105mm Artillery Rounds employ this setup using adjustable powder charges and Fixed ammo in the 105mm Main Gun round in the M48A5 and M60 series tanks.