Use of alternate energy to load a gun

[hz1363]

Can someone help me regarding a concept in gun mechanism??
In the current mechanism a part of the chemical energy of the gunpowder is used to load the next bullet.Had this energy not been used to load , would it increase the range of the gun?? and if so, then is the increase significant??

 

[Simon Bridge]

The energy needed to insert the next bullet into the breach is provided by the spring in the magazine.
The energy to eject the old shell and re-cock the weapon is, indeed, from the energy in the gunpowder which would otherwise have gone into recoil.
http://science.howstuffworks.com/machine-gun5.htm

If you go forward through the lik - you'll see other methods.

This would have a slight reduction in the range of the bullet over bolt-action weapons - but not so you'd notice at any range at which you'd be accurate. The energy to cock the weapon can also be supplied with little effort by hand - so, at most, you'd lose about as far as you can throw the bullet.

Comparison of bolt-action to semi-automatic sniper rifles

 

[SteamKing]

Engaging targets at extreme range with an automatic weapon is an iffy proposition at best. These weapons' most devastating work is done at relatively close range.

Most of the long range weapons are single shot bolt-action types anyway. They are cheaper to build and easier to maintain in the field.

 

[Simon Bridge]

My information is that the US Army snipers use semi-automatics (M21 system) while the Marine snipers use bolt-action M40-series rifles like the Reminton M700. In practice, neither system particularly out-ranges the other. There are simply bigger factors to consider. The weapon choice reflects likely mission profiles.

Light full auto weapons are strictly short range of course, but not usually because of the reduce muzzle velocity from the energy drain of the chambering system.

 

[SteamKing]

The M21, the newer M25, and the M40 are are all built using older rifles. The M21 and the M25 are both built from selected M14 rifles, while the M40 is built using a Remington 700 rifle, a civilian weapon. The M21 and the M25 are semi-auto, while the M40 is bolt action. Interestingly, all three rifles have about the same max. range (about 900 meters, although 820 meters is quoted for the M21).

 

[Simon Bridge]

The M21, the newer M25, and the M40 are are all built using older rifles. The M21 and the M25 are both built from selected M14 rifles, while the M40 is built using a Remington 700 rifle, a civilian weapon. The M21 and the M25 are semi-auto, while the M40 is bolt action. Interestingly, all three rifles have about the same max. range (about 900 meters, although 820 meters is quoted for the M21).

Neat, is that the manufacturers quote - and does that include the effect of the supressor?

 

[hz1363]

I was comparing Lee-Enfield and AK 47. The effective range of Lee-Enfield is 500m whereas that of AK is 300-350m.
Even the effective range of M16 is 350-450m. I believe even an increase of 50m will be quite effective.But i am not sure wether this difference is due to bolt-action and automatic or some other reason.

 

[SteamKing]

In trying to figure ranges amongst such radically different designs, I think you have to look a lot of different factors. The size and shape of the bullet, the length of the barrel, and the amount of powder are all more important than whether you have a single-shot bolt action versus a gas-operated automatic mechanism.

The Lee-Enfield was designed to be a conventional infantry stand-off weapon, the AK was designed to be an assault weapon to be carried by troops on the move where the fighting was to be done at relatively close range, and the M16 tries to do both, to some extent. The LE and the AK were relatively uncomplicated designs, but the US tried to incorporate at lot of innovative features into the design of the M16 which didn't hold up in combat situations. Its development has been quite prolonged as a result.

 

[Simon Bridge]

I agree - the Lee-Enfield and Ak47 are too different to make a fair comparison - remember to control your variables. The US purpose-built sniper rifles are based on the same or very similar weapons so they make the closest match of the in-field weapons that I've found. What we want for a real-life comparison is the exact same weapon and round differing only in the reload mechanism.

The tldr result is that there are many more significant factors than the energy-loss to the reload mechanism that affects the range of a weapon.

Note: the Lee-Enfield Mk1 is the first rifle I trained on... and I keep finding rubber versions in movies.

The L42A1 was the sniper version fired a 7.62mm NATO round at a muzzle velocity of 838m/s and an effective range of 730m.

Bog-standard Ak47 fired 7.62mm round at a muzzle velocity 750m/s, effective range: 400m (300m full auto)
... "effective" is the range at which you are "reasonably" accurate according to some test done by someone, probably a manufacturer. Notice that the Ak one goes down by 100m just switching to full auto ... i.e. the reduction is due, primarily, to the continuous jolting you get firing it.

If we are going to try to compare them...
Bog Standard L-E fired a 7.54mm (0.303) round at a muzzle velocity of 744m/s, effective range: 503m
... despite a similar round and a lower muzzle-velocity, the effective range is longer.
The lower velocity suggests, all other things being equal*, that less chemical energy was supplied to the bullet in the LE than in the AK ... which would support a conclusion that the bolt-action mechanism is lossier (see note for M41 vs M40 below).

Going to wikipedia (fwiw: their citations in the entries are dodgy but hey ho)
M14: rnd: 7.62mm NATO, mv: 850m/s, eff R: 460m
M21: rnd: 7.62mm NATO, mv: 853m/s, eff R: 835m
... these are both gas-operated, rotating bolt, semi-automatics - yet there is a huge increase in the effective range for the sniper version. It could just be that the sniper version has a bipod and a good sight. We really want to be comparing maximum ranges... maybe the muzzle velocities will reflect the question better?

(The wiki entry for the M25 has a max range of 900m ... which is rubbish, I'd buy that as "effective range" though. The max range is how far the bullet goes horizontally at an elevation of just under 45deg**. at sea-level mean TP. i.e. 1000s of meters. There wasn't enough information in the entry to compare with the other two M14-based weapons, so I left it out.)

How about the bolt-action?

M40: rnd: 7.62 NATO, mv:777m/s, eff R: 900m
... notice the decreased muzzle velocity with the same round for a bolt-action rifle? Again indicating that there is more to figuring the range than the chemical energy applied to the bullet.

Which is the takeaway lesson here for OPs question.

Yes - the automatic action does divert some of the energy that may otherwise have gone to the bullet (and the recoil), and this will affect the range. However, there are other factors that are more significant than this effect... it's probably something the manufacturers would consider as part of the finer points of weapons engineering.

This has been demonstrated in-thread by consideration of the physics involved, consideration of actual in-field weapons, and the opinion of a trained army sniper, which all support this conclusion.
I'd call that a slam dunk. :D


-----------------------
* but all other things are not equal. You want to see how hard it is to compare two weapons see
http://en.wikipedia.org/wiki/Comparison_of_the_AK-47_and_M16
... comparing automatic rifles. Ak47 is compared with the M16A1.

Note: "effective range" means "range at which the desired end is achievable with reasonable accuracy" ... which is almost like not having a definition at all. Who decides what "reasonable" is for accuracy for example? The "desired result" could vary a bit from weapon to weapon too - do you just want to hit the target or kill them? The Ak47 has a spread of 15cm at 100yds while the M16 has 10cm (can't tell if that's mean or what)... it's a wonder anyone misses. Dow the page there's a table nd some commentary - basically the lower accuracy of the Ak is due to the recoil from the heavier round.

** Oh OK - likely less than that. As close to the with-drag max-range elevation that can be reasonable sighted to a target.
http://www.exteriorballistics.com/ebexplained/5th/36.cfm

 

[etudiant]

It has always puzzled me that the discussion of the merits or failings of various combat rifles never mentions the ammunition. Yet that is the key differentiator for range and reliability.
The M16 has a bad rap for poor combat reliability, attributable entirely to the Army's decision to switch propellant for the .223 cartridge from the formulation used in the original Stoner AR15, which was the basis for the M16. The Stoner was reliable and could handle dirt, unlike the M16, because its ammunition was properly formulated.
The AK47 vs Lee Enfield discussion is pretty theological, most combat today is pretty close range, mostly urban, so shooting further than down the block is rare. The Lee Enfield could provide aimed fire at 800 yards, as the 'Old Contemptibles' proved in Belgium in the early days of WW1. That is out of reach today except for specialized sniper rifles.

 

[Simon Bridge]

It has always puzzled me that the discussion of the merits or failings of various combat rifles never mentions the ammunition. Yet that is the key differentiator for range and reliability.

Agreed - it's psychology ... you generally see the rifle and not the ammo so the weapon is the rifle when it is properly considered the rifle plus the ammo.

i.e. the notoriety of the ".44 magnum" - people think it's "the most powerful handgun in the world" (thanks to Dirty Harry) but's it's actually the ammo.

The AK47 vs Lee Enfield discussion is pretty theological, most combat today is pretty close range, mostly urban, so shooting further than down the block is rare.

The discussion, as such, is "on topic" :- considering that the question posed concerned loss of energy to the bullet affecting range. The distinction between "overall range" and "effective range" has been noted. If that is "theological", so be it ;)

 

[hz1363]

I know that most of the modern battles take place at urban location and the average range over which a firefight takes place is about 300-400m. I stressed on increasing the range because the battles that the army of my country fights are those in the mountains.And at 10000-15000 ft increasing the effective range even by 50m will mean that a soldier will have to climb 50m less against opposition fire before he can shoot at the enemy. And at the same time it should be no less than any other gun when it comes to fighting at a 300-400m range.

 

[SteamKing]

At those altitudes, you are shooting above much of the atmosphere and ranges will naturally increase a bit due to the thinner air.

 

[etudiant]

I know that most of the modern battles take place at urban location and the average range over which a firefight takes place is about 300-400m. I stressed on increasing the range because the battles that the army of my country fights are those in the mountains.And at 10000-15000 ft increasing the effective range even by 50m will mean that a soldier will have to climb 50m less against opposition fire before he can shoot at the enemy. And at the same time it should be no less than any other gun when it comes to fighting at a 300-400m range.

For those kinds of situations, long range firefights at high altitude, classic rifles and scopes are still the best. However, there are technical enhancements being demonstrated that allow aimed fire at 1000-2000 meters using suitable ammunition.
See https://tracking-point.com/ for the source;
http://arstechnica.com/gadgets/2013...yards-shooting-the-17000-linux-powered-rifle/ for a demonstration.
Note that this is still classic ballistics, not the DARPA funded smart round concept which is built around a guided 25mm projectile.
In general, long range combat is likely to become much more lethal over the next decade, simply because it is a solvable problem, much more tractable than IEDs or urban combat.

 

[Simon Bridge]

I still think that the decrease in range for the same weapon as an automatic is a small issue - compared with everything else that will affect the shot. You'll find your country's military has already thought of this. The distance a soldier has to climb is only one factor in the choice of weapon.

You've seen that for sniper weapons, range is an important factor. However the US Army and Marines made different choices for procurement because other factors were also important - like how fast you need to be able to acquire and shoot new targets.

OTOH: if you are someone like a government official charged with weapons procurement or R&D for the military - and you want to rethink the current solutions - and you are unhappy with the expertise at your disposal - then pm me and I can do a review and write you a report. The kind of detail you need is not the sort of thing we'd do in a free-of-charge forum :)

 

[blkexp98]

The army also uses the M24 which is a Rem 700 action. As you said the mission chooses the weapon if they have that option. In my experience like Mr. Bridge noted the velocity difference isn't much to really dictate the choice. The Navy also uses the M21 as a weapon in their inventory. Overall weapon weight is another consideration where they may pick one over the other.