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RecyMech

Where can I find 105 Light Gun please?

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Addendum to last post......just found (& bought) a handbook on the 105 from Vintage Vehicle Manuals.

Looks like it might have some usefull drawings inside.

 

Just waiting on the postman !

 

H

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OK lads! ROF, Rechy Mech, and I will be taking over the Clubhouse workshop and forge for a while!! :cool2:

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H

 

You obviously just need to ask the right question!

 

Although RARDE(FH) was the original designer of the Light Gun, when the Royal Ordnance Factories were privatised the rights passed to them. BAE Systems (as they are now) having purchased RO, along with most of the rest of the UK land defence companies, are now the Design Authority for the Light Gun.

Its a long shot but you could try writing to them at BAE Systems, Global Combat Systems - Weapons, Barrow-In-Furness, Cumbria; addressed to Chief Engineer, Artillery Systems to see if you can get any assistance.

 

 

Tony

 

This was the original 'workshop'

 

 

ROFN_2000.jpg

 

 

 

 

and what became of it.

ROFN_2002.jpg

 

 

 

It's now a 45 acre commercial office site with a Homebase store located at the bottom left hand end.

 

 

 

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Sickening isn't it? There's a good chance most of Fort Halstead will end up as a council estate!

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Hi RecyMech

 

I was a fitter-gun with LAD 47 Fld Regt, when they had 105 mm Light Guns in the late 70s. I worked on both the L118 (which the regiment was equipped with) and the L119 when 3 Bty borrowed some for a while. The L119 is a different beast compared to the L118. Not only are the breaches different so are the muzzle brakes, and the muzzle brake clamp when towing the gun (due to the shorter barrel). The L118 has an electrical firing box, where the L119 has a firing lever. Sights and things like the air pressure in the recuperator where not the same. I am not too sure if the balance springs were of different length again because of the shorter barrel.

 

Note about the firing platform. Firing platforms are placed directly on the spot the Battery Surveyor and GPO had selected, the gun is then wheeled on to the platform and fixed by the steel cables to the platform. This ensures the gun remains in the same spot when being given a new target. Not too sure if it is as important today with the on board gadgets but it was when the laying of the gun was done by using the coordinates from the CPO and TARAs in the Command Post it was. Traversing the gun was a lot easier using the firing platform, especially on an anti-tank shoot. I trick of mine was to pick the gun up by the gun spike and traverse it a full 360 degrees on my own. The new gunners to the battery were amazed that the skinny gun fitter could do this, none figured out that I had elevated the gun so it was balanced on its wheels.

 

The gun could be moved on sort tows using the A frame under the cradle. This was the main support for the barrel when being transported by Puma helicopter. It was introduced when the RAF still had the Wessex. The gun had to be split in two, cradle and recoiling masses in one load and the saddle and trail on the second lift.

 

To get the gun into the travelling position the right hand wheel had to come off. To keep the gun within the width to load on to one of the then RAF transports the saddle would have come into contact with the wheel when turning the barrel round. The whole trail would have had to be redesigned after the RAF only had Hercules left. I spent most of my time sorting out wheel knock from this wheel and found if the crews kept the face plates of the wheel and brake drum clean then there was less knock. We had some boffins from Woolwich come and investigate the wheel knock with our guns. When I told them that my batteries guns had less knock after we started to keep the face plates clean they poo pooed it and said I was lucky not to have as many problems as others were having. After leaving REME one of the chaps I worked with was in a TA gunner unit and he was moaning to me about the wheel knock so I suggested that they cleaned the face plates. He came back to work after an exercise and said that my method worked.

 

Lastly personal a note about the ammunition. As I had to be on the gun position when they were firing them I would often join a crew if they were sort of gun numbers. Spending a day lugging the semi fixed US ammo was more knackering than what appeared to be twice the effort with the British separate ammo.

 

If you feel I might be able to answer any questions please do contact me.

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Hi Spider,

Cheers for that...once again some interesting reading & tips picked up. I'm going to read through that again & I think there'll be a few questions I might bounce off you as well.:clap:

 

Old_ROF,

I tried getting in touch with BAE some time ago regarding another matter & just got ignored. The bigger the company...etc etc (& the other thing is as soon as you mention the M (model) word you treated like a nerd & they switch off):banghead:

 

Train spotters have a lot to answer for !:argh:

 

Best regs........H

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One of the reasons that the muzzle brake for the L20 ordnance (L119) was so large/heavy was to compensate for the shorter barrel. By having this heavy mass on the end of the shorter barrel the effective weight on the elevation gear remained the same, the out-of-balance loads matching. This was intentional so that the balancing springs would not need to be changed or altered when an ordnance swap was carried out.

 

In addition the recoiling mass also remained the same - this should have meant that the recuperator pressure would not need any adjustment either. There was no problem with the recoil buffer as the firing loads from the US ammunition was lower than that of the UK ammunition.

 

There was a PIP (Product Improvement Program) started to update the Light Gun in the 90's which addressed a whole raft of issues including the knock-off wheel nut and the A-Frame finger 'trimming' tendancy. Unfortunately the program was stopped due to lack of interest/money from the MOD. Some of these improvements have since been incorporated into the latest build standard as modifications.

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Hi ROF

 

The heavy muzzle brake on the L119 makes sense in keeping the balance on the elevating gear the same.

 

The pressure in the air cylinder of the L118 was 750 psi. The L119 was different, one of the gunners managed to break most of the valve off when he was charging it up and I had to replace it. I recall the pressure was slightly higher but it was over 30 years ago and cannot remember what it was. Same gunner was very good at breaking things. They had to ban him from being the one who either swung the barrel from travelling position into battery or releasing the saddle travelling lock. When on the barrel he would swing it before the lock was undone or forget to undo the lock when someone else swung the barrel. I got into trouble for ordering too many replacements because of him but afterwards I did become good at fixing the travelling lock. He was put out of harm’s way in the officers’ mess as a steward.

 

 

Hi RecyMech

 

As a railway modeller......:cheesy:

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Where to get one? H'mm, my guess is that those floating around or in collections are protoypes, and significantly different to the production version, you need to read the Trials UHB to understand how different. I think UK converted its knackered guns to ceremonial. AFAIK the only UK disposal were their 14 L119s in a couple of batches in the last 10-15 years. Currently Australia is disposing of all theirs, and they have both types of elevating mass for each carriage, the L118s being unused in most cases (a sorry saga of a screwup).

 

I like the photo of the new mods in post #17, new Selex box for the layers unit, to replace the Denel laptop and invites question as whether it includes NABK software and a wireless interface for comms to FC-BISA. Also new MV radar and repositioned inertial unit. However, what about the new direct fire sight, or is that only a theatre entry standard, either way I don't believe a direct fire sight has been abandoned.

 

Of course origianlly L118 was a procurement saga, MoD appointed a military project manager, but only a Lt Col, the design authority had a more senior civil servant in charge and ROF also had a more senior person, neither of the civil servants would recognise that the PM was the customer's man and called the shots.

Edited by watcher

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This thread has brought the memories flooding back. :cheesy:

 

Me taken the picture just before heading of to lark hill from 17 trg reg and depot in 89

 

413239_442133355828065_35557904_o.jpg

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Hi RecyMech

 

I was a fitter-gun with LAD 47 Fld Regt, when they had 105 mm Light Guns in the late 70s. I worked on both the L118 (which the regiment was equipped with) and the L119 when 3 Bty borrowed some for a while. The L119 is a different beast compared to the L118. Not only are the breaches different so are the muzzle brakes, and the muzzle brake clamp when towing the gun (due to the shorter barrel). The L118 has an electrical firing box, where the L119 has a firing lever. Sights and things like the air pressure in the recuperator where not the same. I am not too sure if the balance springs were of different length again because of the shorter barrel.

 

Note about the firing platform. Firing platforms are placed directly on the spot the Battery Surveyor and GPO had selected, the gun is then wheeled on to the platform and fixed by the steel cables to the platform. This ensures the gun remains in the same spot when being given a new target. Not too sure if it is as important today with the on board gadgets but it was when the laying of the gun was done by using the coordinates from the CPO and TARAs in the Command Post it was. Traversing the gun was a lot easier using the firing platform, especially on an anti-tank shoot. I trick of mine was to pick the gun up by the gun spike and traverse it a full 360 degrees on my own. The new gunners to the battery were amazed that the skinny gun fitter could do this, none figured out that I had elevated the gun so it was balanced on its wheels.

 

The gun could be moved on sort tows using the A frame under the cradle. This was the main support for the barrel when being transported by Puma helicopter. It was introduced when the RAF still had the Wessex. The gun had to be split in two, cradle and recoiling masses in one load and the saddle and trail on the second lift.

 

To get the gun into the travelling position the right hand wheel had to come off. To keep the gun within the width to load on to one of the then RAF transports the saddle would have come into contact with the wheel when turning the barrel round. The whole trail would have had to be redesigned after the RAF only had Hercules left. I spent most of my time sorting out wheel knock from this wheel and found if the crews kept the face plates of the wheel and brake drum clean then there was less knock. We had some boffins from Woolwich come and investigate the wheel knock with our guns. When I told them that my batteries guns had less knock after we started to keep the face plates clean they poo pooed it and said I was lucky not to have as many problems as others were having. After leaving REME one of the chaps I worked with was in a TA gunner unit and he was moaning to me about the wheel knock so I suggested that they cleaned the face plates. He came back to work after an exercise and said that my method worked.

 

Lastly personal a note about the ammunition. As I had to be on the gun position when they were firing them I would often join a crew if they were sort of gun numbers. Spending a day lugging the semi fixed US ammo was more knackering than what appeared to be twice the effort with the British separate ammo.

 

If you feel I might be able to answer any questions please do contact me.

 

Hi Guys

I was also a Gunfitter/Armourer on light gun and had similar problems with wheel knock and wheel bearings. Larkhill dust caused lots of bearing problems despite replacement oil/dust seals. The knock was cured by cleaning the faces of the drum and face plate on the knock off wheel, I belive the Kremlin at Bordon sent out a fix for the problem. Comments on the gun platform reminded me that ROF used explosive forming removing the need for a top die, a water dam around the lower die, the part machined metal plate, some very technical explosive, BANG and plate formed!! Inoted Robmixartillary mentioned wire wound barrels, these seem to be used on some naval equipments, I saw some being cut up at Pompy in the 60's at what could have been Pounds Yard. Light Gun barrels are of monoblock constrection "one peice" and Autofrettarged the inner layers fo metal being stretched beyond their elastic limits while the outer lavers spring back gripping the inner layers, usualy achived by pressing a metal former through the barrel of by hydrulic pressure.

Great to hear the technical bit of guns being discussed on the forum Happy New Year to All

Regards

Robin

(Artifficer)

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Autofrettage was invented by the French about a century ago. UK didn't start using it until after WW1. Until then barrels were either wire bound or 'built-up', starting with the A tube and adding more tubes around it. Not all 'modern' guns use autofrettage, eg the L13 ordnance of Abbott was't, being an SP the weight saving wasn't worth the additional cost and steel technology had also improved a lot since autofrettage was invented making monobloc construction without autofrettage possible. I'd guess that wire bound RN barrels dated to pre-WW2, but they are traditionalists so perhas not.

 

The mid-life upgrade of a few years back developed explosively formed titanium for some parts, presumably building on technology developed for M777, but it didn't enter service due to cost.

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Not all 'modern' guns use autofrettage, eg the L13 ordnance of Abbott was't, being an SP the weight saving wasn't worth the additional cost and steel technology had also improved a lot since autofrettage was invented making monobloc construction without autofrettage possible.

 

That's very interesting, I'd always assumed that the Abbot ordnance was of similar construction to the Light Gun, but obviously not!

 

Andy

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That's very interesting, I'd always assumed that the Abbot ordnance was of similar construction to the Light Gun, but obviously not!

 

Andy

 

The L13 barrel was designed using 'non-autofrettaged' or 'limited overstrain' principles. With this methodology the physical size of the finished tube assumes that a degree of overstrain will be produced if the gun design pressure is reached and hence the bore will be permanently increased in size and the outer layers will be in tension.

 

Both the L19 and L20 barrels are autofrettaged during the manufacturing process. As identified earlier this process deliberately oveloads the barrel which causes an amout of deformation at the bore. This leads to compressive stresses at the bore and tensile stresses towards the outside. The design allows for the post process machining to obtain the final barrel size with the required strength to meet to gun pressure design needs.

 

There are two methods to achieve this autofrettage. Firstly is the Hydraulic method which seals the barrel and pumps in high pressure fluid which causes the required degree of overstrain. Secondly is the swage mandrel process whereby an oversize mandrel is pushed through the bore again causing the overstain. The barrel is machined to suit the different process methods to anable the end design to be achieved.

 

Hope this helps to clarify and not confuse.

 

edit: sage to swage!

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