Mills no5, 23 and 36, all marks.

[Nismosonic]

Hi guys,
Was wondering what is earliest and latest dates of manufacture for the Mills series grenades.
The earliest ive seen a No5 is 7/15 latest 11/16, earliest 23Mk1 being 8/16, latest 11/16.
Im very interested in when the dates of production started, and ended for each type and also how long they overlap for instance,, the bodies of 5,23Mk1 and 23MkII are identical so I expect them to overlap maybe more than the 23MkII and the 23MkIII, then 23MkIII to overlap with 36 as virtually identical bodies etc etc.
And then to go into detail with the No5, what dates did the lever change from early drilled type, to plain, then the later ribbed? Ive seen this ribbed on dug up no5s with 9/16 and 10/16 dates, but used on all 23MkI and II.
Ive not found a website that details production in the way, although Dave Sampsons has many baseplugs to compare.
Hope this isn't confusing!

:sad:

 

[Millsman]

From memory

Ist Trials with cylindrical and oval prototypes March 1915 (France - Guards Regiment)
Production started with order for 50,000 in April (but note W Mills had to spend a huge amount of time assisting the first manufacturers and production was very slow at first)
Earliest dated plug found is May 1915
Last dated plug for the No 5 12/16
Evidence of No 5 being used as a rifle grenade from May 1916.
First 23 Mk 1 seems to be 8/16
All No5s became 23 Mk IIs from 1/17
Not sure of earliest 23 Mk II but think it was 1/17
First 23 Mk III 9/17
First 36 Mk 1 9/17

The 23 Mk II and Mk III and the 36 Mk 1 overlapped through to the end of the war.

No 23 MK II phased out in early 1920's. Last No 23 Mk III seems to be 11/18

Last No 36's produced 1972.

Please note that the dates contracts were awarded to manufacturers is probably not a good guide to when they started production of various types. The best evidence is from base plugs. There was also about 2 month delay from manufacture to use in the field.

 

[Nismosonic]

Thanks very much, any info on the introduction of the lever types? (drilled early lever, ribbed lever and plain lever)

 

[Millsman]

Levers

Drilled (slab sided) Prototypes through to about February 1916
Plain (Flat but with formed top) unclear start date but may be late 1915 to early 1917.
Convex - Mid 1916
Ribbed - Around September 1916.
Flat stamped - September 1917 with the 23Mk III through to 1972.

Lots of overlaps and grenades have been found with odd levers that seemingly don't match plug dates. Not a precise science!

 

[digimax]

Here two Mills plug N5 dated from Jan.1917

 

[Millsman]

Cheers. I had heard of one but had not seen one. They are the exception rather than the rule I think. Most No 5 plugs end 12/16. Note the overstamp on one. The JR plug is very rare.

John

 

[Bonnex]

In the really difficult category is the No 5 Mark II. Engineering drawings were advanced to Mark II for a very short period before reverting to Mark I. I think I have seen a No 5 Mark II plug (many years ago and memory fades).

Herewith a scan of the filling drawing annotations relating to the Mark II.

View attachment bonnexscan0855.pdfView attachment bonnexscan0857.pdf

 

[Millsman]

I've only ever seen one photo of a plug marked No 5 Mk II. It was made by the Dudley Foundary (DF.Co)

I think the MkII was killed by the 23 Mk III.

John

 

[Bonnex]

Thanks John. Seemingly the No 5 filling drawing was not reverted to Mark I until 1919 (difficult to read) so the cut-off date for the actual manufacture of the No 5 Mark II would likely have been the 'Obsolete for Future Manufacture' date which, as you say, would have been set by the timetable for the No 23.I'm glad you have seen some evidence of at least one contract using the Mark II specification.

 

[Millsman]

Norman

My suspicion is that a small batch of Mk II base plugs were made but ended up on No 5 Mk I grenades.

I've got a set of the manufacturer's specifications for the No 5 Mk I, No 23 Mk I II and III and the No 36. I don't think the No 5 Mk II ever got that far so as to be sent out to the factories.

Design stage only I think.

John

 

[millsbomber]

This Mk2 certainly got to the front as found around Ypres,,,,,,,, Dave

 

[Millsman]

That's the chap. May be the only one ever found?

John

 

[millsbomber]

That one is in Belgium and another is in France, there is also a S.G.B which i have yet to visit the collector and photograph,,,,,, Dave

 

[Bonnex]

Norman

My suspicion is that a small batch of Mk II base plugs were made but ended up on No 5 Mk I grenades.

I've got a set of the manufacturer's specifications for the No 5 Mk I, No 23 Mk I II and III and the No 36. I don't think the No 5 Mk II ever got that far so as to be sent out to the factories.

Design stage only I think.

John

John,

Sounds very plausible. There was a spec:

L3579 Grenade, Hand, No 5, Marks I and II /L/ Filling

in the IWM in 1976 (!), which I thought I had a copy of but cannot locate it. Interestingly the equivalent pairing of an empty manufacture spec mentions only the Mk I. From the information I have I do not know what constitutes a Mark II. At one time I thought it might be the vented striker but, of course, there are (or were) literally millions of Mk Is with vented strikers.

Given that the drawing I mentioned yesterday and the spec above both being Filling documents rather than for manufacture I now wonder if the Mark II was solely to do with a Filling enhancement - sort of No 5M; now there's something to ponder over

Best

 

[millsbomber]

These Examples of No5 Mk II base plugs are very uncommon, the only one (as picture) i have seen with my own eyes, it was collected from the battle field and the rest of it was destroyed, one day lets hope a complete example will come to light and we all might learn the difference,,,,,, Dave

 

[Snufkin]

Annotation on one of the the No.5 manufacturing drawings states "Numerical advance to MkII and dimensions of cap chamber and centrepiece amended. Approved 25.5.16". The cap chamber (anvil) was lengthened and the centrepiece cup height reduced to ensure the anvil butted tightly against the base plug when the latter was screwed home - blinds had been encountered previously because the anvil was sometimes found to be slightly loose within the centrepiece cup, and when the striker fell the .22 cap failed to fire. It is a design change to guarantee functionality that might have been deserving of a revision from MkI to MkII (Norman is best placed to confirm or refute that).

The slotted striker was suggested by Mills and Morgan in August 1915 but wasn't seriously discussed by the War Office or Ministry of Munitions until a year later, August 1916 - after the MkII nomenclature appeared.

Interesting comment from Dave that another MkII plug is marked SGB - both Stourbridge Glazed Brick and Dudley Foundry Co (DFCo) were effectively one and the same operation, at the Moor Lane Works, Brierley Hill, Dudley.



Tom.

 

[Millsman]

Annotation on one of the the No.5 manufacturing drawings states "Numerical advance to MkII and dimensions of cap chamber and centrepiece amended. Approved 25.5.16". The cap chamber (anvil) was lengthened and the centrepiece cup height reduced to ensure the anvil butted tightly against the base plug when the latter was screwed home - blinds had been encountered previously because the anvil was sometimes found to be slightly loose within the centrepiece cup, and when the striker fell the .22 cap failed to fire. It is a design change to guarantee functionality that might have been deserving of a revision from MkI to MkII (Norman is best placed to confirm or refute that).

Interesting comment from Dave that another MkII plug is marked SGB - both Stourbridge Glazed Brick and Dudley Foundry Co (DFCo) were effectively one and the same operation, at the Moor Lane Works, Brierley Hill, Dudley.

Tom.

Interesting and informative post Tom (as always). Upgrading the centrepiece and anvil hardly seems to constitute a jump from Mk 1 to Mk II unless you included a lever change as well at the same time. However the situation with levers has always seemed chaotic and I feel that as long as the requisite % passed the post filling tests, they were sent into use. The gap you mention between the anvil and the baseplug was probably down to minor variations in manufacture of castings, centrepieces and anvils. I know that in some cases bombers used plasticine to seal the base of No 5's and this may also have been a bit of padding to close that gap.

The date of the proposed Mk II changes is interesting as it fits in with the planned move to a No 23 Mk I as well. Perhaps it was the No 23 Mk I that killed the No 5 Mk II and the changes were just incorporated into general production????

John

PS Added - It's interesting that Delhomme annotates his diagrams of the No 5 and No 23 slotted strikers with 'No 5 Mk 1 et Mk 2'

 

[Millsman]

John,

Sounds very plausible. There was a spec:

L3579 Grenade, Hand, No 5, Marks I and II /L/ Filling

in the IWM in 1976 (!), which I thought I had a copy of but cannot locate it. Interestingly the equivalent pairing of an empty manufacture spec mentions only the Mk I. From the information I have I do not know what constitutes a Mark II. At one time I thought it might be the vented striker but, of course, there are (or were) literally millions of Mk Is with vented strikers.

Best

Hi Norman

I've dug out my copy of L3579 and it's interesting to note that the 'II' is a hand annotation. So there was never a reprint to encompass the Mk II.

It looks like the idea progressed to a certain stage and then perhaps the changes Tom highlighted were integrated into normal production. I expect some base plugs were made in anticipation, but were probably just put on Mk I's.

John

 

[Nismosonic]

Thank you all who of contributed to this thread, I am so much the wiser now than before I started it.
As much as I bow down to all of your superior knowledge a few things come to mind reading through... The date of the MkII plug is 8/16, this is in line with No 23 MkI manufacture, so has the same maker (DFCo) been seen on No23 base plugs around the same date? Obviously the MkII plug is visually the same as a No5 Mk1 plug, unless the threads are a different depth...??
So, apart from the baseplug, what else is different on a no23Mk1 compared to a No5Mk1? here, the change (as far as I know) was only the ability to fire from a rifle, yet the grenade got a whole new number, not just a MK change!!!... yet, when no23MkII changed to 23MkIII the grenade body was significantly altered... fascinating.

 

[Snufkin]

Thank you all who of contributed to this thread, I am so much the wiser now than before I started it.
As much as I bow down to all of your superior knowledge a few things come to mind reading through... The date of the MkII plug is 8/16, this is in line with No 23 MkI manufacture, so has the same maker (DFCo) been seen on No23 base plugs around the same date? Obviously the MkII plug is visually the same as a No5 Mk1 plug, unless the threads are a different depth...??
So, apart from the baseplug, what else is different on a no23Mk1 compared to a No5Mk1? here, the change (as far as I know) was only the ability to fire from a rifle, yet the grenade got a whole new number, not just a MK change!!!... yet, when no23MkII changed to 23MkIII the grenade body was significantly altered... fascinating.

Dudley Foundry certainly made 23I base plugs - attached scan is of an 8/16 dated example.

From TWSD report week ending 20 May 1916: "Instructions have been received to prepare 1,000,000 Mills' grenades with attachment for firing from a rifle. This demand involves the provision of special base plugs, 5-inch rods, and blank cartridges; also 35,000 cups for attachment to the rifle of three different patterns."

This modification of the No.5 became the No.23 MkI, so effectively the only difference between the No.5 hand grenade and the No.23 MkI rifle grenade was the base plug (and rod).

As you say, a mere change of base plug entailed a change of type number from No.5 to No.23 MkI, whereas the complete redesign of the No.23 MkII grenade (by Frederick Vickery and Francis Gibbons) resulted in only a Mark change to MkIII. And then finally just a slightly different base plug gave yet another type, the No.36.




Tom.