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4.2 Inch ML SB Technical Pub

Petrock

Member
Hello everyone.

Does anyone have a British / Australian publication on the ammunition for the 4.2 Inch muzzle loading smooth bore?

I have a UXO that we have not been able to positively ID and I'd like some alternate resources.

The fuze is giving me the most trouble as it is extremely degraded. If you've got a digital copy of either British or Australian pubs, I'd love to see them.

Thank you
 
I have DWS Notes on Ammunition, Issue No 15, Section IV, dated 1943, unfortunately not in a digital format and in fragile condition. The text with regard to fuzes states, `The only fuzes used with the 4.2 in. Mortar Bomb are Fuzes, Percussion DA Nos 152 and 152A. For a description, see DWS Notes No 15, Section I, para 17.'

Types of bomb to which these were fitted include Chemical (Y mixture), Smoke, HE, HE Streamline, Practice Bursting, Practice Inert and Drill. The smoke bomb filling could be one of three variants: white phosphorous "PHOS", chlorosulphonic acid mixture "CSAM". or titanium tetrachloride "FM". Those filled with phosphorous were for service (presumably meaning operational) use and those filled CSAM were intended for practice. The document does not say whether those filled FM could be used operationally, or for practice, or for operational and practice use.

Under the fuze it was possible for there to be a 12 dram CE pellet or an exploder "R" CE. Please note also that Practice Bursting bombs may be filled with calcium chloride, or with calcium chloride and white phosphorous. The 4.2s that I have found have been Practice Bursting or Smoke. In seawater the fuze degrades to grey flaky material and even a sludge. The detent is made of brass, is one inch (25 mm) long, and is tapered toward the top of the fuze.

Drill bombs had one cut-out in the tail fins. Chemical, Smoke and Practice Inert had two cut-outs in the tail. HE and Practice Bursting had no cut-outs in the tail. The Streamline shape in 1943 was only filled with HE. The MkI Streamline body was of cast iron. The MkII Streamline body was of steel. Aside from the differences in the tail units, all types other than the Streamlined HE had parallel sides and a guide band for obturation at each end of the main body of the bomb. If you see Khaba's 4.2 Inch mortar impact post I placed a post on it some time ago that shows the tail of a 4.2 inch bomb. I just realised that I incorrectly labelled it as a Streamlined bomb tail but with two cut-outs it could be from a bomb filled with Chemical, or Smoke, or Practice Inert. However, the remains of the bombs were mostly ripped open from the inside and were in two large chunks so I would hazard a guess that they were Smoke.

I also have a copy of DWS Notes No 15, Section I, printed in October 1942. The Fuze information at para 17 is as follows, ` 17. Fuze, Percussion, DA, No 152 - This is a zinc alloy fuze and unlike the other fuzes it is provided with a thin metal striker cover.

The fuze is armed on firing, when the detent sets back, releasing the ball and thus allowing the striker to rise by the extension of the striker spring. The shutter is then free to open and is moved by its spring until the 5 gn Det (5 grain detonator) is directly under the needle.

Fuze No 152A differs from Fuze No 152 only in the metal of the retaining ball.

Normally, fuzes are inserted with Luting, but for the 152 Fuze, when no set screw or other fixing device is provided, RD 1158 is to be used. This is to prevent the unscrewing of the fuze when removing the safety cap.'

I will try to place a scan of the fuze with this post. Oh well, better twice than not at all! Please let me know if this has helped.

Fuze Percussion DA No 152.jpgFuze Percussion DA No 152.jpg
 
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Hello everyone.

Does anyone have a British / Australian publication on the ammunition for the 4.2 Inch muzzle loading smooth bore?

I have a UXO that we have not been able to positively ID and I'd like some alternate resources.

The fuze is giving me the most trouble as it is extremely degraded. If you've got a digital copy of either British or Australian pubs, I'd love to see them.

Thank you

Do you have some photographs you could post?
 
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