What's new
British Ordnance Collectors Network

This is a sample guest message. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

No's 5 and 23.


Well-Known Member
I'd be grateful if anyone can tell me the visual differences between the Mills No 5 and the 23?
not a lot externally different. The main differences are the striker on the No23 has a slot in the striking face and the base plug is threaded for a launching rod.
The main difference was that the shoulders (where the pin goes through) were different from the 5. Also the baseplugs, where there were a number of different shapes. Solid brass or iron for the Mk1. A sort of wingnut for the Mk2 and Mk3 made of cast iron. Base plugs for the Mk2 were often 'copper washed' - a light coat of electroplated copper to stop the iron rusting. The No 23 obviously took the 5 inch rod as well. The advantage of 23 was that it could be used as a rifle grenade as well as a hand grenade. Only a small minority of No5 were made for as rifle grenades.
It is very hard to tell a 23/ 1 body from a No 5. There are characteristics of both in each mark which can be seen when the grens are found. Later gren bodies have the pinholes drilled further into the lugs and the pinhole is rebated, i.e, the pinhole is slightly recessed but i have seen dug no 5s with this and 23/1s without it. Earlier produced bodies would just not be wasted.
Also, with the numbers that were produced, 65 Million, during WW1, large numbers of no 5 bodies were used as 23/1s just with the addition of the 23 base plug due to such a vast number of them being produced.
I would say its very difficult to be precise here. I have a really good 23/2[one of my best Mills] with a plug dated 4/17 and if you put a no 5 plug on it, i could not tell if it was wrong, and i can assure you i have scrutinised it for this reason. I have no doubt over its originality.
However, a general concensus is that if the pinholes are deep, ie, further into the lugs its a 23 but i dont think this is a defining characteristic.

Last edited:

I guess my way of thinking is a little backwards, but I "assume" any advertised original grenade has been "put together". I would rather get my own body and parts, do it cheaply and not even have to wonder if I have an over-priced pieced together grenade. Gives me one less thing to worry about and they display awesome! Dano
Not always the case Dano,

i aquired and sold a boxfull of No 5s recently[still have the box, aint selling that] that was found on the Somme that were all kept together. Each gren was deactivated by competent EOD and each part was kept with each gren. I suspect that this dosnt happen often and that most Mills grens[not all] are made from composite parts. However, does that matter? They were mass produced, with a non return policy, and everything was made to a pretty high standard so does it matter if the bits didnt all come from the same gren? In my mind it dosnt matter in the least as they were all put together from millions of parts. It the fact that its a complete Mills bomb that counts.
Early Mills had an unslotted striker, later ones and 23s had a slotted one, thats a main difference re a 23/2 to a no 5.

Last edited:

Hi andy, I think we're pretty much on the same wave-length. I've bought a No5 before with a broken ear but all parts there, then bought a good No5 body really cheap and ended with a very nice No5 MK1 for under 100.00US. I think maybe I got my wording a bit sideways, sorta..Dano
Bit more info on the differences between a No 5 Mills and a No 23.
Paul stated that a difference was that the 23 had a slotted striker. True, but this was introduced from October 1916 and therefore was also used on No 5s so this is not a definitive difference. As for body shapes etc, i think the only real difference apart from a possible deeper position of the pinholes was the introduction of ther 23/3.

No 5 Mark II

For those interested in the minute details of these things. The slotted striker seems to be the only defining element of difference between the No 5 Mark I and No 5 Mark II. The Mark II notation was approved 24th May 1916 (on file 54/Infantry/1670). On 24th July 1919 the Mark II notation was removed from drawings (file reference 57/24/4476). Lists of Changes never recorded the No 5 Mark II and it slipped into obscurity. However contracts were clearly awarded for No 5 Mark IIs since a few (I have handled two) baseplugs are clearly marked (and genuine).

Collectors will be aware that No 5s (Mark Is) can commonly be found with or without slots (and some with centre fire strikers but that is another story).
Last edited:
Hi Norman,

centre fire strikers? Would that be a problem with the rimfire .22 used with the detonator or are you refering to the initial batches of dets that didnt have the centre cut out and papered over as the later ones were. I thought that the .22 was too small a calibre to have any thing but a rimfire. I have heard rumours that the grens produced in France[Dunkirk] may have been centre fire. If so, what sort of round was used in the det?

CF Strikers


It certainly was a problem. I cannot remember the scale of the drama on file but reports of prematures were put down to Stokes Pistol strikers, which were centre-fire, being used by accident in Mills grenades**. You will appreciate that the mechanisms are similar.

You know this Andy but for those watching this thread a number of contracts for Mills grenades were let to four French firms by GHQ in 1915. The Vanderslys company of Dunkirk apparently produced centre-fire ignition for their version of the Mills. This is an area worthy of some research but it is difficult to be sure of locating genuine examples since very few of the French Mills grenades were made (180,233). I have seen one recovered by a Belgian EOD pal which is likely a Dunkirk grenade and this one was certainly centre-fire although the igniter set was missing (for obvious reasons).

I don't know what cap the French used to produce a CF igniter. The very early Mills grenades of the Roland spherical pattern had CF igniters but the Mills-Roland oval hybrid used RF and this set the pattern for the Mills (apart from the possible French departure).

** Note: If you pressurise safety fuze it 'burns' faster. Using a centre-fire striker on the Mills rim-fire igniter can fire the cap but is likely to block the central vent hole, the gases from the safety fuze have no escape and pressure builds up causing rapid burning (causing higher pressure etc). This was also a feature occasionally of unslotted rim-fire strikers which is where this thread began I think.
Last edited:
Yeah. I have both No 23s and No 5s with the slotted type striker, but I'm pretty sure you don't get the unslotted striker on the 23s as apparently they were withdrawn quite early on due to poor air circulation getting to the fuse. I think it is more common to see makers marks stamped onto the bodies of 23MK2s onwards too, but I'm only going on what I have seen.