Important!
ALL ARTILLERY SHELLS 20MM and larger CAN CONTAIN EXPLOSIVE!
If you have not yet contacted the Police /EOD, do so at once. CAREFULLY remove the projectile from your house, and place it in an open area as far from people/buildings as possible. Do Not drop, bump or jar it. it doesn't matter if your buddy played with it as a kid, unless an expert certifies it as inert, it is to be considerd DEADLY DANGEROUS!!!!!
Keep the casing. It is harmless.
Be aware, that artillery shells can contain other things besides explosives. "DUD" rounds are NEVER SAFE. They have been known to go off from impacts, or for no apparent reason, years, and even decades later. They have been known to survive numerous impacts, even go through fires without going off, and then later detonate. World War I shells might contain poison gas! (along with a bursting charge)
In 1977, while stationed in Germany, some soldiers found a "dud" artillery shell. They took it back to the barracks, and as it was Saturday night, drank some beers. The shell got knocked off a table in their second floor room. The Duty NCO heard the noise, and when he found out what happened, called EOD and evacuated the barracks. The next morning, the entire company got several hours of training on "unexploded ordnance". After which, they witnessed the detonation of the shell. It was a WW II German White Phosphorus round, and was quite impressive. If it had gone off in the barracks, it wouold have destroyed one wing of the two story concrete building, and set fire to the rest.
The shell in your picture appears to have an intact fuse. This indicates the STRONG possibility of an explosive charge. I vas unable to make out the markings on the base of the case from your picture, could you post them please, also any markings on the projectile portion.
Measure the diameter of the case mouth (please don't mess with the projectile). The size in inches/mm and any markings will help aid in identifying the round. There are literally hundreds of different rounds it could be, so anything you can tell us will help.
If Explosive Ordnance Disposal identifies it for you, please post and let us know. If it is actually inert, you have an interesting paperweight.
If I sound like a nervous nellie about this old thing that has been kicking around for decades, it is because I have some small experience with these things. If it is inert, call me any name you want, but until you are ABSOLUTELY SURE, don't take the risk! If you can, get in touch with military EOD, they may be able to ID it. Chances are the local police bomb squad won't. They will likely just take it to a safe location and detonate it with explosives. To be "sure".
Upon closer examination of your pictures, the shell does not appear to be very large, and I think I can see the number 37 on it. If it is a 37mm shell (case mouth measurement - approximate) then it may contain explosive, or phosphorus, but is highly unlikely to have poison gas (if it is the right age for that) WW I gas shells were larger, usually 105mm or larger. The gas (as a liquid) was contained in glass spheres inside the projectile, along with a bursting charge.
It may also contain nothing at all, but best to be safe, and sure.
Good Luck.
Don't lose any sleep over it, just put it where it won't hurt anyone if the impossible happens, contact the authorities, and follow their instructions. I have never heard of anyone being prosecuted for something like this, even in those rare instances where they have turned out to be live. Usually they turn out to be inert, but don't take chances.
Hope I haven't scared you too badly, but until you know for certain, this is no joking matter.
