Primers for 12PR 8CWT and 12CWT Cases

[peregrinvs]

Hi,

I bought this primer thinking it would fit into my 12pr 8cwt case, but the thread on the primer is deeper than the socket in the case and the primer won’t screw in any further than the top of the socket. (I’m guessing the thread in the socket stops short of the top, preventing the longer primer screwing in all the way)

So what is this primer for? It’s marked RL IV. Does the 12cwt case have a deeper socket? What would be the correct primer for my 8cwt case?

Thanks,
Mark

 

[tigbrand]

I have no info on different mks, but have a few primers, what date are your cases/primer?

 

[peregrinvs]

I have no info on different mks, but have a few primers, what date are your cases/primer?

The primer is undated. The case was made in 1898. The primer is 60mm long and the threaded portion is 18mm long.

 

[ron3350]

This is the adaptor for the 0.4" Vent Tubes as used in 12Pr 12 cwt, 4.7" , 6" etc Naval cases.
The centre is an electric Mk 1V vent tube as it has smooth rim. Percussion tubes have 4 grooves.
Here is my example with the internal booster. This shows a percussion vent tube.
I cannot quote from David Ibbetson's excellent book as I have a friend rapt in reading it at this moment.Damn.

Peregrinvs. You should be able to knock the tube out of the adaptor with a wood dowel.

 

[Falcon]

This primer should be correct for this type of case.

On all of these cases I have seen, the threads run straight through the case, there is no shoulder or step in front of the threads.

I have seen this before where the primer will not screw all the way in. I have wondered if the threads in the case were made with a very slight taper to aid sealing.

I bought a correctly sized tap for cleaning out these threads, which has worked very well as they are also often damaged, corroded or filled with dirt and dried metal polish.

It also usually helps to clean up the external primer threads with a thread file. The correct die was too expensive as it is a non-standard size, and external threads can be cleaned more easily.

I would be happy to run the tap through the threads on your case if we are ever in the same place once the lockdown is over.

 

[Depotman]

This is the adaptor for the 0.4" Vent Tubes as used in 12Pr 12 cwt, 4.7" , 6" etc Naval cases.
The centre is an electric Mk 1V vent tube as it has smooth rim. Percussion tubes have 4 grooves.
Here is my example with the internal booster. This shows a percussion vent tube.
I cannot quote from David Ibbetson's excellent book as I have a friend rapt in reading it at this moment.Damn.

Peregrinvs. You should be able to knock the tube out of the adaptor with a wood dowel.

View attachment 164661View attachment 164662View attachment 164663

I suggest you unscrew the small screw in the shoulder first! It's meant to lock it in. Depotman

 

[ron3350]

No need to unscew. There is a spring and ball bearing from memory that is for friction tightness.
I did undo one once and found it was not necessary.The screw is punched so not meant to be removed.
If the primer misfired they just replaced it with another tube after removing?
I only have 2 adaptors and both tubes almost fell out with a slight tap. Oil the spring before replacing again. Just my thoughts.

 

[Depotman]

No need to unscew. There is a spring and ball bearing from memory that is for friction tightness.
I did undo one once and found it was not necessary.The screw is punched so not meant to be removed.
If the primer misfired they just replaced it with another tube after removing?
I only have 2 adaptors and both tubes almost fell out with a slight tap. Oil the spring before replacing again. Just my thoughts.

Thanks Ron, I've certainly seen the spring and ball bearing you mention, but can't recall if all versions had it! (Old age!) Depotman