What is the Bore Diameter of a 37mm Launcher?

Common sense tells me it is supposed to be 37mm. But when I measure my Spikes Tactical Havoc, it measures 1.560 inches, which converts to almost 40mm.
Whats going on here?

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When I got my Havoc it measured 39.56 mm and now it measures just over 40mm. the second tube I have measures 38.9mm.

39

My first tube measured 38.9mm which I then bored out to 40mm when I DD'd my HAVOC. I had to get a second tube as my Form1 only has one gauge marked down and you "must" be able to revert to it's original approved Form1 status. My spare tube measures 38.8mm

MadDog

ETA 40mm tubes found on M203's and M79's are not exactly 40mm either.

Thanks for the replies. I thought I had somehow recieved a DD unknowingly. I was kind of happy at first because I was going to register it as a DD and have it bored out. And thought the boring was already done for me.

Measure any 37mm launcher and you will get many different bore diameters. From 26.5mm to almost 40mm. Some are even 40mm, however the diameter is not measured at the bore for a DD. It is measured at the barrel end. If your barrel can launch a 40mm round, or chamber a 40mm adapter, it qualifies. Some bores do extend the length of the launcher, some are 8", some are more, some less. Depends on the manufacturer.

Many 37mm launchers are made ammo specific. That's to say that a Federal launcher is made to handle Federal Ammo, Def Tec launchers, Def Tec ammo. Some are interchangeable, some are not. Some rims are thick, some not. Nothing like Mil Spec 40mm stuff. 37mm is in the hands of the manufacturer, and there are no real "specs". GROG

grog is THE MAN when it come to all things 37mm and 40mm.

MadDog

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