Help with a b166 box

[13th battalion]

Hi guys, I've got a b166 dated 1942, it isn't in particularly good condition but as I've rubbed it down, the original stencilling has come through. I'm a bit puzzled though as it has some markings I haven't come across before.
It appears to say "3 IN HOW HE " then it has a capital E in a broken box which is underneath a "Q" in a circle. It definitely looks to be a HOW rather than a MOR which I expected to find.

Ive had a look at other threads and posts and none of them mention 3in How. I've attached some pictures, to show you.

any help would be great fully appreciates.
thanks
Steve

 

[reccetrooper]

Maybe this? https://en.m.wikipedia.org/wiki/Ordnance_QF_3-inch_howitzer

 

[tankbarrell]

The E in the box is the propellant code, WM (Waltham modified), WMT or WT.
The B166 is a box that was used for many things beyond its normal use.

 

[13th battalion]

Thanks for the help guys. Do you think it's better to leave the box as it is or redo it.

 

[13th battalion]

Does the q in a circle signify "quick fire".