Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Domed Shoulder brass for improved performance    Ammunition <20mm

Started 1-Aug by gatnerd; 849 views.

From: gatnerd


Came across this today, first time I've ever seen this style of cartridge design. Rather then a traditional cartridge shoulder like we all know, this one is a domed, similar to the end of a gas cylinder:

Closer view of another done by Warner:

Video of this brass being formed:

Has this ever been done before? 

Curious what a 5.56 or 6.5cm etc with this domed shoulder would be capable of vs a standard one / this designs implication for future conventional case cartridge design.

  • Edited 01 August 2021 4:46  by  gatnerd

From: stancrist


It looks like that extra 15 grains of powder comes mostly from eliminating the case taper of the .416 Barrett.


From: Red7272


Weatherby have been doing that for decades and claiming it is beneficial.  At the same time wildcatters have been blowing the cases out to almost straight with 40 degree shoulders to improve the case capacity. Hydraulic flow is about ensuring laminar versus turbulent flow. To what extent this happens in gun chambers where there is a restrictive plug in the barrel that will be making a mess of flow anyway is debatable.  Target shooters who are interested in both accuracy and velocity have come to the conclusion that below is the ideal case type. 


From: nincomp


I seem to recall a cartridge with domed shoulders very similar to the .416 Warner roughly 15 years ago.  It was considerably smaller than .416, however.  Maybe for varmiting or benchrest shooting?   Hopefully someone else has a better memory. 


From: roguetechie


That's a pretty interesting way to try to make brass competitive with true velocity etc


From: Sten556


Good luck getting a decent and easy to make and measure datum for the headspace.

Also on my FEA simulations of cartridge cases a conical shoulder was never the issue, however the joints between it and the neck and body are, but it can be easilly solved via generous radius and cadequate clearance between the case and chamber. The "flat# bit doesn't need to be big, just enough to have a reliable reference point.