1" Navy shell

In cleaning up my very cluttered office space today at the insistence of my wife, I ran across a shell I didn’t remember I had, and I don’t remember even where I got it. It is a dummy or drill round (2 holes in the brass case, no primer) that is headstamped (in part) 1"10 Mk. I 75 cal. and there is also an anchor stamp. The projectile has a brass or copper driving band and appears to be of steel and about 1" in diameter. Date is “9-42” I’d suspect it is either US Navy or Royal Navy. So what is it and what gun was it used in? Should be a few old salts out there that are familiar with this.

I think I found the answer on Wikipedia - an AA gun used by the US Navy in the early part of WWII.

The 1.1 inch AA gun was the standard US Navy onboard system buring the late 30s and early 40s. It was also called the Hudson gun and the Chicago organ or Chicago piano. It was replaced by the 40mm Bofors which had a much longer range. The drill cartridge is the most common of these shells but none are common any more. The nose fuzed HE with a tactical fuze is hard to find most have fuze caps but not fuzes. Most of this ammo was dumped into the ocean during and after WW2. At WW2 end only one ship still mounted the 1.1 inch. It was the USS MASON a destroyer escort which was the first US Navy ship with a black crew.

There is a fair amount of information about both the gun and its ammunition at: navweaps.com/Weapons/WNUS_1-1-75_mk1.htm

Apparently one of the few mounts that did not get destroyed. This one is on the USS Yorktown CV-10