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Guns wearing out questions

FormerHorseGuard

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Not an expert by any means. But maybe some of the Master Gunners and techs can answer some simple questions for me without giving away any details from the opsec world

M777 , how many rounds would a Canadian gun put thru the gun in a year? What is the expected life span of a barrel?

I figure from reading various sources they are firing 5000 plus rounds a day thru their guns. So how long will a barrel last?
 

GR66

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Very interesting article. I wonder how many assumptions on various types of equipment on expected usage are proving to be way off in this conflict?
 

FJAG

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I'll leave it to Petard to answer some of the more technical issues. He is THE SME on all things artillery technology in this forum.

I'll say in general that modern artillery is significantly more complex than the 105mm C1 and the 122mm D30 of old. Once you get to self propelled guns there is also the issue of the automotive elements of the carriage that lead to complexity. When I was the BK of a Cold War M109 battery, we had 13 technicians (that's 10% of the battery's manning) to keep our six guns humming. Without significant ongoing, running maintenance, stuff stops working. When crews ride their guns hard and put them away wet, stuff stops operating. Not just breaking but frequently just gummed up. I doubt if Ukrainian batteries have anywhere near the detachment maintenance nor the tech support that our M109s had.

Barrel wear is a significant issue especially for these newer longer range guns and projectiles. You simply can't ram 95 lbs of steel through a barrel under enormous pressure without taking a little bit with it. The higher the propelling charge, the greater the speed and friction and the greater the wear. With the 105 mm C3 there are 7 propelling charges to the round. Firing Charge 7 (increments 1 to 7 combined) gave you the greatest range and thus the greatest wear. For every charge 7 fired the gun was considered to have fired one EFC (Effective [or Equivalent] Full Charge). If you only fired Charge 3 (ie increments 1,2 and 3) then you only fired a fraction of an EFC (I can't recall what the EFC values for each charge were anymore but let's say 0.25 as an example.). These vary with the different types of ammunition fired. So its not the number of actual rounds fired but the number of EFC's fired that determine the barrel life of a particular gun.

Other things effect that too. Around 2003/4 we introduced a new longer range round for the 105mm in Canada which used a new steel driving band on the projectile. This driving band was particulalry hard on the barrel of the LG1 and increased the wear on the barrel dramatically.

There are other issues too. On the M777 there is a loading tray for the projectile. The proper drill is to load the gun, fire it and place a new round on the tray after it has fired. Crews found that they could load faster if a new round was placed on the tray immediately after the first round was loaded and before the gun was fired. This non-authorized drill, however, put a strain on parts of the system and caused them to malfunction repeatedly. Similarly, the drill requires two men to manually ram each round. It can be done with one but this can cause improper seating of the round in the barrel. Detachment training and skill levels do matter - a lot.

Complex parts such as electronics and hydraulics can fail at the best of times but once put into field conditions they are susceptible to misuse or rough usage which increases their failure rates.

With respect to usage, that varies greatly. No gun in the Ukraine is putting 5,000 rds through per day. That may be the Ukraine's expenditure across the board but any given gun probably fires from zero to dozens to, at most on rare occasions, a few hundred rounds per day. Remember that on many parts of the front artillery engagements are very few and at best opportunistic when a target of value is found. During particular phases of an operation, such as near Kherson, that activity might increase for a few days while their supported arms are active. I don't want to compare Afghanistan to Ukraine but at their busiest, Canadian gunners with four to six guns were putting just over 3,000 rounds downrange during a six month roto. While some of those were at full charge at max range most were fired at much less than max range or charge.

I don't for a moment doubt that the Ukrainians are going to have maintenance issues. When we rushed the M777 into service two of the weaknesses in our preparation was the number of technicians we were able to train fully and the spare parts supply chain. Our wpns techs were learning on the job and for a while spare parts were coming off a damaged and cannibalized gun in KAF. We had issues supporting four guns of one model for a while. The Ukrainians have suddenly received highly complex guns of a number of models with very restricted parts support. They seem to be geniuses in keeping their older Soviet equipment on the road with local fabrication complexes, but there is only so far that even genius will take you when these types of systems are rushed into service.

As far as how many rounds do Canadian guns put through a year, I can't really answer for right now. Back in the 1970s we were firing off a lot of 105mm that was reaching shelf life expiry and our 12-gun L5 regiment fired approximately 10,000 rounds per year. That's roughly 850 rounds per gun per year. Virtually none of those were fired at Charge 7 (for much of that time we were limited to Charge 6 except in operational situations) so each gun was receiving substantially less than 500 EFCs per year. Barrel wear was not an issue at all and I've never hear of the L5s requiring barrel replacements before the gun was retired. The LG1s, on the other hand, in the mid 2000s fired far fewer EFCs but had serious barrel wear issues because of those projectile driving bands. Today's gunners fire far fewer rounds in training than we did back in the day.

Just an aside. You can adjust for barrel wear. As barrels wear down the projectiles velocity drops which effects the range to which it flies. If one constantly measures the projectiles' velocity then one can adjust the elevation that the gun is fired at to compensate for that drop. All of our guns these days have a muzzle velocity radar (also called a chronograph) mounted on the tube which provides accurate data to allow for those adjustments as the barrel wears.

🍻
 

FormerHorseGuard

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What I was meaning the Ukraines were firing 5000 plus shells a day across all the guns.
It is interesting to read and understand what everyone is doing over there. I find it hard to find 100% accurate information on what is going on. But barrel life was interest to me
 

Colin Parkinson

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Apparently several 20mm and 35mm guns use nylon driving bands to reduce heat and barrel wear, I wonder if that would work for artillery rounds?
 

KevinB

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Apparently several 20mm and 35mm guns use nylon driving bands to reduce heat and barrel wear, I wonder if that would work for artillery rounds?
Rifling in a howitzer barrel is significantly deeper and sharper. While fired at lower velocities most of the ultra high density polymers used in the 20-50mm rounds would crack with the amount of deformation required out of a 105mm (or higher).
 

FJAG

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Apparently several 20mm and 35mm guns use nylon driving bands to reduce heat and barrel wear, I wonder if that would work for artillery rounds?
That's outside my level of expertise. Driving bands have two main purposes: to seal propelling gases to stay behind the projectile and to engage the rifling of the barrel so as to give a predictable spin. That's why they have to be a substance that's softer than the barrel material so that they can deform to create that seal and engage the rifling. My guess is that the depth of rifling (as @KevinB points out), the weight of the projectile, the violence of the propelling charge and the residue that they leave in the barrel are all factors that would indicate if a given substance is useable or not. Generally softer metals are used for artillery shells.

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NavyShooter

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20mm CIWS barrels which use a polymer 20mm pusher Sabot are actually gain twist barrels - they start at a low rate of rotation (almost zero) and increase the twist rate as they approach the muzzle - this prevents some of the potential for destroying the sabot as it enters the rifling, and gives it a chance to accelerate the spin rate.
 

KevinB

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20mm CIWS barrels which use a polymer 20mm pusher Sabot are actually gain twist barrels - they start at a low rate of rotation (almost zero) and increase the twist rate as they approach the muzzle - this prevents some of the potential for destroying the sabot as it enters the rifling, and gives it a chance to accelerate the spin rate.
Interesting, I knew gain twist barrel cause a lot of issues for drive bands (leakage of gasses due to the change in the twist deforming larger areas of the drive band) and I guess the longer sabot system helps with that?
 

FormerHorseGuard

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" Ukrainian forces were already firing 6,000 shells a day in June, Ukrainian officials said at the time."
The US is looking for a company to make 12000 shells a month.
The US isn't the only one with an ammunition problem. Canada has shipped 155 mm shells to Ukraine and is now asking South Korea to replenish its stocks.

how much longer can they fire at that rate?

Canada has donated spare barrels for the M777



the numbers are amazing to follow.
 

Spencer100

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Super dumb question. To decease barrel wear and help seal the projectile and barrel from the gasses why is an oil or lubricant not used? Thinking piston in an engine. I'm sure someone will scold me for being an idiot.
 

KevinB

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Super dumb question. To decease barrel wear and help seal the projectile and barrel from the gasses why is an oil or lubricant not used? Thinking piston in an engine. I'm sure someone will scold me for being an idiot.
A few issues with that.

1Friction causes pressure, pressure causes velocity… Propellants generally burn at a higher temp than gasoline (or diesel), and few lubricants will last long in a barrel.
Barrels have been coated with a number of different materials and liners made - but at the end of the day, you are pushing a heavy projectile, the barrel is but one wear item on a howitzer, the recoil mechanism also needs maintenance and parts replacement. The desire for lightweight guns than can be more easily transported and the law of ‘no free lunch’ means that something has to give.


" Ukrainian forces were already firing 6,000 shells a day in June, Ukrainian officials said at the time."
The US is looking for a company to make 12000 shells a month.
The US isn't the only one with an ammunition problem. Canada has shipped 155 mm shells to Ukraine and is now asking South Korea to replenish its stocks.

how much longer can they fire at that rate?

Canada has donated spare barrels for the M777



the numbers are amazing to follow.
We don’t have a 155mm ammo issue currently down here. That number is an additional requirement on top of other increases that provide for us to continue to supply Ukraine as well as maintaining our war stock.
If you look at how much ammo we sent over again this month, you may notice it is nearly 1/4M 155mm rounds, which really isn’t a lot compare to what we have.
 

FJAG

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Super dumb question. To decease barrel wear and help seal the projectile and barrel from the gasses why is an oil or lubricant not used? Thinking piston in an engine. I'm sure someone will scold me for being an idiot.
Here's a pdf that covers quite a bit of ground on artillery barrel wear and erosion factors.

We do apply a thin layer of oil to an artillery barrel when cleaning them for the same reason as it is used on rifle barrels - to retard corrosion.

I'm not so sure that the primary purpose of oil on an engine piston is to seal and lubricate the piston although it does that. I think it's principle use is to carry heat away from the piston and chamber. That's the same way that you use oil when cutting metal on a lathe.

There's a substantial difference between a continuous long time friction action (such as in an engine block) and an occasional (albeit violent) round being fired. I'm not sure that "reoiling the barrel" after every shot would decrease barrel wear or increase it by introducing a medium that would capture dirt and debris that could increase abrasion of the barrel. Just a guess.

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KevinB

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Additives have also been tried to reduce flame cutting on the throat and bore, again with a resultant decrease in velocity (and/or significantly increased fouling).

There really isn’t a free lunch when it comes to launching a projectile down a bore.
 

FJAG

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Additives have also been tried to reduce flame cutting on the throat and bore, again with a resultant decrease in velocity (and/or significantly increased fouling).

There really isn’t a free lunch when it comes to launching a projectile down a bore.
Physics is a bitch.

😁
 

Spencer100

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That’s what Gerald Bull said, too…

#dingdongmossad
Does anyone else get a sad feeling about a guy like that? Going to far to pursue a dream. I think of DeLorean in the same vain. Throwing everything for a goal and in the end it costs everything. But then without people like that we would just be sitting in caves.
 

Colin Parkinson

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Super dumb question. To decease barrel wear and help seal the projectile and barrel from the gasses why is an oil or lubricant not used? Thinking piston in an engine. I'm sure someone will scold me for being an idiot.
Fats on projectiles were used in the early days of rifled guns, to reduce wear and to help with the sealing. Wax is used on lead bullets to reduce leading and effects velocity,
 

Good2Golf

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Does anyone else get a sad feeling about a guy like that? Going to far to pursue a dream. I think of DeLorean in the same vain. Throwing everything for a goal and in the end it costs everything. But then without people like that we would just be sitting in caves.
Sad for sure. Back in the day, my father was an aerospace engineering professor and Gerald Bull was one of the grad students of one of his colleagues. He says Bull was crazy smart, but the profs all wondered ‘I wonder what he’ll get up to when he graduates?’
 

Weinie

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Sad for sure. Back in the day, my father was an aerospace engineering professor and Gerald Bull was one of the grad students of one of his colleagues. He says Bull was crazy smart, but the profs all wondered ‘I wonder what he’ll get up to when he graduates?’
About 62 years and 13 days.
 
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