Mills No.5 Training Range Clearance

[Millsman]

Someone that I know has been metal detecting on an old WW1 training ground in Kent. He showed me the pieces he has found.

These are Mills No.5 grenades and they have all been fairly cleanly cut in half. There are some jagged bits but most of the cuts are fairly clean.

They have not been surrounded by any small splinters of shrapnel so may have been dealt with separately? Could these have been blinds?

All the base plug pieces found on the training area indicate heavy usage in early 1916.

Comments appreciated.

 

[justin]

John, I saw similar items recovered from an archaeological excavation in Somme area back in 2014. We found 9 Mills top halves, not quite as cleanly broken as yours, but close together, within trench backfill. All of ours retained the pin and lever, however, so guessed they had been detonated by an explosion nearby.

 

[Millsman]

Thanks Justin. I suppose it could be possible that an external shock like a shell explosion could shatter the Mills bodies at a weak point, but this is on a training range so less likely that on the battlefield. In your case the grenades were probably still in their crate. These come scattered around an area about 30 feet square.

 

[Mike_H]

I would suggest that these were the result of use of unfilled grenades with detonator only.

 

[Millsman]

I have thought of that but in early 1915 William Mills did some tests with non filled grenades fitted with just a standard detonator and the bodies did actually split into a few quite large lumps. A Mills grenade with full charge was found to break up into around 3000 pieces varying in size from 1/2" to microscopic.

 

[TimG]

From the 'Text Book of Ammunition, 1926'



The asymmetric location of the detonator could also result in only a partial detonation of the charge. This might well be the case in these examples.

TimG

 

[Snufkin]

They have not been surrounded by any small splinters of shrapnel so may have been dealt with separately? Could these have been blinds?

Comments appreciated.

They are certainly not the remains of blinds as blinds were strictly disposed of, by either blowing up or burying in a hole 3' deep or more.

Over the years I have had two empty standard Mills No.5 casings (one semi-relic, one non-relic) which have broken in two around the centre line in the process of being refurnished with centre pieces. I recollect the semi-relic did have a slight crack around the centre, and on tightening up the centre piece the casing broke. The non-relic seemed fine, but I remember to my chagrin on tightening the centre piece there was a distinct snapping sound and the body split perfectly in two. I also had at one time a French made (so called Dunkirk) Mills grenade that had a crack around three quarters of the circumference, but I moved it on before the two halves parted on me.

Centre pieces were inserted at the factory with significant force in order to attain as good a mechanical seal as possible. This would have created a permanent tensile force within the grenade body as the top of the striker sleeve pushed on the inside of the crown, and the bottom fuze chamber was set with Pettman cement in the mouth of the body. Flawed casings under constant tensile stress over time might well crack, and the centre line serration groove would be a likely point of failure.

With thousands of grenades being used for training, a few dozen found cracked over time and put aside in one area seems plausible. Levers and pins were retained for use on throwing dummies, so would explain their absence on the discarded bodies. The stripped bodies might have been deliberately hammered open to empty the insensitive ammonal/amatol/alumatol, of which the ammonium nitrate would quickly wash away when it rained.

Several found together in France with pins and levers does suggest the possibility of a flawed batch from one manufacturer.

Occasionally grenades did accidentally leave the filling factory without having been filled with their bursting charge. If not detected before loading with igniter sets, the detonation of the detonator would indeed create a few large, irregular-shaped fragments.

 

[Millsman]

From the 'Text Book of Ammunition, 1926'

View attachment 178871

The asymmetric location of the detonator could also result in only a partial detonation of the charge. This might well be the case in these examples.

TimG

It's interesting that on the same site they have found a number of striker / spring combinations with a brass cover tightly bound around the spring. This is clearly a brass center piece tube after detonation. The blast has clearly pushed in the brass all around the spring, indicating an even all round blast impacting on the centrepiece. I've never seen the logic of the 'off centre detonator' as the explosive content was on all sides of the centrepiece and would have exploded in the same nano second.

I was given one of these brass centre piece tubes with the spring / striker inside and I'll put up a photo tomorrow.

 

[Millsman]

As in the previous post here are the photos of the striker/spring combination inside the compressed centre piece tube. Three views giving a 360 degree view. As you can see the compression of the brass tube onto the spring and striker appears very consistent. It's almost as if its been shrink wrapped in brass. There are no areas less compressed indicating the pressure inside the Mills body was consistent before the body broke up. I can't see any evidence of the asymmetric position of the detonator affecting the internal pressure.

 

[US-Subs]

Not to be a killjoy, but to me the damage to these items is not very consistent with detonation. Some of what you are showing seems more like what we would see on chemical weapons that had been buried, then had frozen. Liquid fill would sometimes expand and compress different components, break parts in certain ways, etc. Perhaps these got wet, the area flooded, then froze? Repeatedly over time? Just a thought -

 

[Millsman]

Not to be a killjoy, but to me the damage to these items is not very consistent with detonation. Some of what you are showing seems more like what we would see on chemical weapons that had been buried, then had frozen. Liquid fill would sometimes expand and compress different components, break parts in certain ways, etc. Perhaps these got wet, the area flooded, then froze? Repeatedly over time? Just a thought -

I wouldn't discount it. Kent has had some pretty bad winters since the Great War.

I certainly agree with your first statement.

 

[Snufkin]

A couple of images of a French-made Mills I mentioned in previous post. The crack around the centre serration groove is highlighted - on tracing it fully I seem to recollect it extended about 3/4 of the circumference and I felt it was only a matter of time before the internal stresses popped it completely.

Third image is a close-up of a tool used to screw home the centres. A flawed casing might break there and then, but it might hold to reveal itself much later.



.

 

[Millsman]

Not to be a killjoy, but to me the damage to these items is not very consistent with detonation. Some of what you are showing seems more like what we would see on chemical weapons that had been buried, then had frozen. Liquid fill would sometimes expand and compress different components, break parts in certain ways, etc. Perhaps these got wet, the area flooded, then froze? Repeatedly over time? Just a thought -

More on this. The parts don't seem to have any remains of pins or other parts though one has the remains of a centrepiece. The question is; what state did these go into the ground in?

 

[TimG]

Your images of the brass wrapped striker are most unusual. As I'm sure you're aware, the recovered striker and spring from a detonated 36M invariably has severe localised damage adjacent to where the end of the detonator is located - some appear to be 'explosively' welded together (might just be rusted together over the period of time). This specimen has nothing, other than the shrink wrap.


With respect tho the base halves, are the internal threads stripped, or evidence of base plug/centre piece external threads stripped? Or have they been looted for non-ferrous metal?

 

[Millsman]

Your images of the brass wrapped striker are most unusual. As I'm sure you're aware, the recovered striker and spring from a detonated 36M invariably has severe localised damage adjacent to where the end of the detonator is located - some appear to be 'explosively' welded together (might just be rusted together over the period of time). This specimen has nothing, other than the shrink wrap.


With respect tho the base halves, are the internal threads stripped, or evidence of base plug/centre piece external threads stripped? Or have they been looted for non-ferrous metal?

Hi Tim

The detectorists found a few of the 'shrink wrapped' spring striker combinations, so it's not a one off. I've just wire brushed a couple of the base parts and the threads look fine.

 

[Snufkin]

Tim,

Bear in mind there was a big difference between the detonators used in the two wars - in WWI a commercial No.6 detonator with FoM filling, and in WWII the more powerful military No.6, with ASA-tetryl.



Tom.

 

[justin]

I can confirm that the 'shrink-wrapped' (very suitable term) effect is very common - see below. These also come from a Great War practice range and show a great uniformity, therefore from 'normal' detonations. The ones that are less intact are the antimony style central tubes, which have a tendency to crack, possibly where the det was located. Incidentally, I cut open one of the brass shrink wrapped examples and inside was a well preserved striker, impressed with the grooves of the spring. The spring itself was still in good condition too, but suffered from my attempt at extraction.

 

[Millsman]

An update.

Last week I visited the WW1 training ground with the detectorist. It was my first visit there, though I have known about the training area since 2008. The detectorist has the permission of the farmer to search the land.

We started a search in the area and found a few more shrink wrapped striker / spring combinations. Also, there was a King George III penny and a Civil War Musket ball. After about 90 minutes searching the detectorist hit a very large strong signal that initially looked like a long pipe (a rifle?). We started digging and found we were digging into a big concentration of Mills No. 5 bodies in a pit. Most were split in two (top and bottom) but there were others with pieces broken out with 80% of the body complete. The depth was around 10 - 12 inches with most sitting on the chalk bedrock.

Some of the lower body parts still had the brass centre pieces in and others showed where the aluminium centre pieces had rotted away leaving a pale blue / green residue.

One lower part appeared to show the centre piece partly extracted from the body.

We dug out about a third of the signal area so there is still a lot buried there. I'm coming to the conclusion that this might be a place where blinds were salvaged, with centre pieces and base plugs sent for recycling and the bodies split (hammer and bolster?) to allow nature to wash away the explosives. I have found a reference to blinds being made safe by the detonator being removed - (a bucket of water close by to drop it in if it starts burning on extraction) and the fact that few of these bodies have centre pieces and none have base plugs makes it look like the remains of a salvage operation.

The few base plugs found by the detectorists are all brass cup 1916 type so these remains may have been caused by salvage work demanded by the late 1916 brass shortage.

I'll sort out some photos soon.

 

[Millsman]

Here are some photos.





Above: Top - What was dug up this week. This from a hole around 30cm wide X 100 cm long X 25 cm deep.
Main row: Three base sections with brass centre pieces intact, base part with centre piece partly withdrawn, more 'shrink wrapped' strikers, a Mills tool and lastly a top section showing quite a lot of original paint, unseen for 106 years.