British 4.2-inch Heavy Mortar

[horsa]

That mounting in the center is one I borrowed for comparison to my others in the shot so I don't know it's history. But it is marked 4.2 and has the Australian D/|\D markings on it with a 1943 date. I'd say the one you posted is virtually identical though. Could be yours was an earlier produced 3" mount that was modified to the 4.2" format as those bigger mortars were coming on-line since it has a 1942 date.

For the barrel, the length of the smooth bore pipe is 60 inches with a muzzle outside diameter of 4.75 inches. The first 18 inches from the breech end has an outside diameter of 5 inches.

[wally2960]

Thanks for the detailed mesuraments and the quick reply. I have another question concerning my restaurationproject: which kind of sighting were put on the mortar? After some detailed examination of the wartime photo's I can't see much difference with the 3 Inch mortar sights. Was it common to put 3 Inch optics on the 4.2 inch mortar? greetings Wally

[horsa]

There were two main types of sights used and after the 4.2" mortars got into general issue, it seems they changed the data plates on them to read something along the lines of 3" and 4.2" mortar. The biggest visual difference on the two patterns is how they connect onto the mortar mount. One type has a socket and the other type has a dovetail. In the shot I previously posted showing some mounts, the center one uses a socket type sight and the other two have dovetail mounts.

I can try and get photos of both patterns sometime over the weekend if you need them.

[wally2960]

Hey David, I would be very interested in some pictures of the correct mortar sights used for the 4.2. It seems that my mount was equiped with a cradle of the socket type. Unfoutunatly the socket have been broken off since warend. While cleaning I noticed on the cradle two bolts near the outher edge of the cradle, not far from the socket. They also are present on the wartime picture placed on my forum. Do you know of what use they were? I've posted also new pictures of the cradle (with visible bolts).

http://brechtsoorlogsmuseum.freeforu...-inch-t12.html

[horsa]

Shots of the two basic types of sights used during the war. One on the left has the dovetail and the one on the right has a socket mount. Your mortar mounting used the socket type.





The bolts you were talking about are hard to figure out from the angle. With the cradle and sight adjustment area being incomplete, it could be that someone added bolts to fill the holes.

[horsa]

I've been slowly restoring a 4.2" mortar and finally managed to get some firing pins turned down from stainless steel round bar stock. Originals were firing studs as the launching cartridges each had their own firing pin in a clip attached to the cartridge so they were self contained for launching. Guess that eliminated the chance of a malfunction in the field due to a firing pin breaking or wearing down.

I wanted to load my own cartridges from 12-gauge shotgun shell hulls and prefer a fixed firing pin so the rounds light off on impact with the pin at the bottom of the tube. Plus I have no way of producing self contained caps like they had during the war.

Took my live barrel out over the weekend and used a normal infantry base and legs which I am storing for someone else since my base and legs are the towed pattern which is much larger and harder to mess with for just a few test shots.

Link below is a very short YouTube video showing a single launch of an original round using black powder. I only used enough to throw the round out 225 yards which is extremely short range compared to the wartime maximum ranges of 3500 yards. As such, the round is moving fairly slow so you can see it leave the tube. I also didn't dig in the base since I was using light loads.

http://www.youtube.com/watch?v=TshEHDD-GvQ

Figured it would be OK to add this to the existing message thread since its one of the types of mortars being discussed. And in case anyone is wondering, its a BATF approved destructive device here in the USA so I can legally take it out and get it dirty now and then

[alleramilitaria]

whats the range?