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30 x 136/rr t-328


Well-Known Member
Premium Member
Attached are some photos of the 30 X 136 round.
According to Tony Williams book "Flying Guns The Modern Era" it was for a gun that was developed in the USA in the early 1950's but abandoned in 1957. The gun was front loaded. The reason for this being that it was developed as a turret cannon where it was convenient to have the ammunition feed close to the centre of the turret rather than at the back of the gun.
Because of the way the round was loaded into the gun the rim of the case is only 17mm.
I'm sure Tony can add to this.

All INERT (primer oiled and it rattles!).



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Very nice round. Just a word about the T328 projo. There are a bazillion of them in the U.S. They are found in every size of 30mm case in one collection or another. This is the first time I have actually seen one crimped in a case. They are the standard "case filler". Evidently a huge number were surplussed, and everyone filled their cases with them.

Hi John thanks. Yes I've seen quite a few of the T328 projectiles around, have a few also.
The situation with those projectiles sounds similar to the British Late 40s/ Early 50s .280/30 experimental rounds for the EM2. Only about 50 of the rifles were ever made for trials, but the ammunition must have been made and surplused in the millions. With nothing to fire them, alot of the rounds survive today, and inert examples can be found for as little as 2.
30 x 120/rr case only.

Just got hold of the short brother of the 30 x 136/rr (the 120mm case length version). Its a bit mashed but will do nicely. Will post a photo of the complete round when I dig out the projectile from the spares box.


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Falcon, the base diameter is 17.3mm.
I've not measured the groove, will do when I dig out the measuring thing. Its going to be a couple of mm less.
It is not the same as the .50 BMG as the base diameter on the .50 is 20.3mm. I thought they looked similar but obviously there are not the same.
Perc/Elect primed

Interesting to note that the 30 x 136 round is percussion and the shorter version is electric primed-any reason for this Dave ?
Very observant Chris, I was wondering why too.
This was well experimental so they could have tried all sorts.
From a mechanical point of view, electric priming makes it so much easier to time when things happen in the gun. There are no dynamics for cocking, safing, and releasing a firing pin, and no lock time delay for the firing pin to travel forward and impact the primer once it is released. Reading the description in Dave's first post, if the gun was for a turret, and they wanted to eliminate equipment behind the chamber, then electric is the way to go. One of the reason for the telescoped rounds, was that it shortened the rounds, and therefore the cycling mechanism for loading and extracting, which lowered the weight of the gun, making it much better for aircraft use.
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