.5 in the A11 Infantry Mark I tank

[nickwatts]

Hi, I am deep into researching the fitting of the .5-inch Vickers into the A11 Infantry tank Mk I and have a whole bunch of questions mainly revolving around the dimensions of the .5 Mk V versus those of the .303-inch Mk VI or VII (the AFV versions most likely to have been fitted).
I am very willing to share what I have found from the tank perspective if someone can get their tape measure out and measure a few things!
As you guys are the experts, you may also be able to correct my naming conventions etc.
Look forward to hearing from anyone, best regards, Nick

[Richard Fisher]

Let me know what measurements you are after and I will get the tape measure out when I am with the guns next.

Do you have all the manuals on the guns and their mountings?

Regards

Richard

[nickwatts]

Thanks Richard,

I would really like to know comparisons between the two guns:

1. the diameter of the waterjacket at its widest part of the .303 and .5 (or circumference, either would be good) as it should be no more than the .303. Since the .5 did actually fit inside the .303 armoured housing on the Mark I, it should be about the same size, but is it exactly the same? Or did they have to bodge it a bit to fit?

2. the distance between the end of the ejector tube and the front end of the water jacket on both the .303 and .5 would be ideal - this is because the .303 is, I am led to believe, the shorter distance. In the Mk I infantry tank, the ejector tube had to be 'prolonged' so that the empty shells could still be ejected outside the tank - but I need to confirm this.

3. the length of barrel exposed at the front of the .5, from the front of the water jacket to the muzzle. This seems a lot longer than the .303 and its cup and would have stuck out quite a way from the cast flash eliminator of the Mark I armoured housing.

4. I am also trying to work out how much more of the .5 stuck back inside the turret compared to a .303 - I imagine a comparison of the distance from the back of the mounting block to the very rear of the weapons would do because I don't know where the mounting block locates in the Mark I (I haven't been able to persuade the Tank Museum to let me inside their examples yet!)

Would you know if the .5 was fitted with the shoulder piece when in use inside the Light tanks? I have vague 'first-hand' anecdotal evidence that this may have been the case in the Mark I but I am not entirely sure, and if it was standard practice, that would swing it.

and I would also like to confirm which ammunition would have been available - I am suggesting that this would be the same as in the Light Tank Mk VIb; standard and tracer on the webbing belt, but which were used in 39/40?

and finally (yeh, right!) do you know any official source for the armour penetration capability of the .5 Mark V with these standard rounds?

I know that they had to manufacture a new feed-tray for the .5, as the existing one was to fit the .303 box, and I imagine the .5 tray from the light tank was incompatible. We will probably never know what it looked like, but anacdotal evidence suggests that it wasn't as stable as it could have been.

I have had the wild idea of trying to convince the Tank museum to let me try and fit a .5 in one of their examples but I am not sure that this accords with their current projects or if their static version's .303 is actually on a mount! I don't think it is...

I have access to a friends copy of some manuals:

.303 Vickers Machine Gun Handbook 1930
Machine Gun handbook technical Vol I Pamphlet 1 1940
Machine Gun handbook technical Vol I Pamphlet 2 1940

and these have been helpful to a degree, but no measurements!

Sorry for this host of queries, and looking forward to hearing from you. Any way i can return the favour with tank info, please feel free.
best regards,

Nick

[Richard Fisher]

Hi Nick,

I will take what measurements I can but I don't have the Mk. VII to compare it to (sadly! I would like one a lot). I will work through your post in more detail.

As well as the manuals that you've access to, I would suggest you go to the manuals page on the Vickers website and download at least:

Tank Training, Volume II - Part III, Pamphlet No. 4: Machine Gun Mountings and Appurtenances for use in Armoured Fighting Vehicles
Tank Training, Volume II - Part III, Pamphlet No. 5: .5-in. Vickers Machine Guns Mark V

There are more that may of use as well.

I don't have the data on penetration to hand but there might be something in one of the text books I have.

Regards

Richard

[nickwatts]

Thanks Richard,

I got my friends' copies for a while - as you say they are useful.

Any chance of an update on those measurements?

I have a comparative illustration from the Tank Museum plans for the Light Mk VI but there are no measurements and I cannot be sure that they are in scale to take measurements from.

Best regards, Nick

[Richard Fisher]

Nick,

I started the measurements but for the life of me I can't find the piece of paper I put them on. Then I forgot! I will try and do it again this weekend.

Richard