The INSAS 5.56mm Rifle- A Technical Treatise

[bennedose]

I do not know who made the claim that it was heavier - that was not me. Technically there could be a "sweet spot/sweet range" for a lighter bullet where its momentum might be higher than one of slightly different, slightly heavier design, but without more details about the round and objective tests conducted - I think we are simply going to speculate. I'm not in this trying to prove anything, especially to people whose minds might already be made up. I am simply passing on information that I have read from here and there. If you know different - I have no problem with that.

[TC]

TAR has been procured for the SF but they have several other top of the line assault rifle in their kitty as well...we are waiting for the upgraded INSAS rifle and carbine...trials are on...this weapon has withstood the harsh Indian terrain for sure...its quite an achievement in itself...very few rifles have achieved it and I have been part of few trials...though INSAS needs a lot of improvement but dont write it off...we have been fighting off our enemies with this rifle for a long time now...one can ask them how it tastes but very few will be alive to tell you that actually

Now that is the opinion that matters... coming from an officer who is serving and leading his men in the harshest terrains and most dangerous conditions.
We really don't need to take into account what some internet savvy couch expert with a foreign name writes in a blog with no credentials.

Thanks gladiatorgarg

TC

[bennedose]

fyi:
http://frontierindia.net/some-facts-myt ... of-jacket/

The standard adopted at TBRL for ballistic evaluation by and large follows the National Institute of Justice (NIJ) standard 0101.06. Threat levels defined in international standards are by no means exhaustive and do not cater to the requirements in terms of the weapons like (AK-47, INSAS etc.) and ammunitions (like 7.62×39(KF), 5.56×45) currently available in Indian subcontinent. A NIJ Level III BPJ which offers protection against M80 ball (lead core) ammunition fired from SLR may not able to stop AK-47 or INSAS ammunition having steel core/tip.

[timmy]

Having said that, if one wants to be a physics Nazi then two additional points must be taken into account:

"Physics nazi"? It seems to me that discussing the scientific aspects of a matter like this cuts to the heart of the discussion, and is hardly regarded correctly as a minor detail of ballistics.

1. The minute you replace any proportion lead with an equal volume of steel in a bullet, the lower specific gravity of steel ensures that the bullet will inevitably be lighter (have less mass) than a pure lead bullet. A lighter bullet in turn wil inevitably exit with a higher muzzle velocity given the same propellant energy.

This is true, but not a relevant issue. Lead is about 50% more dense than steel. Are we discussing projectiles that weigh 33% less than normal lead bullets? No. We are discussing bullets of approximately the same weight, which means that the steel-cored bullet must be larger, and if of the same bore, this means longer.

A longer bullet means that it will have more drag, thus slow down faster than a more compact one, given that the compared bullet designs have similar drag. A more dense bullet will retain energy better at longer ranges. So, for short range (given that the steel cored bullet will be of about the same weight as the lead core bullet), there will not be a significant difference between the energy of steel core vs. lead core bullets. (Actually, the steel core bullet, being longer, may experience somewhat more friction in the barrel.)

Because the steel core bullet is not as dense, it must be loaded to a longer length than a lead bullet (taking up more room in the magazine) or it must be loaded deeper in the cartridge case, taking up volume that could be used for powder/propellant.

2. Since steel is more resistant than lead to deformation under stress, a steel core bullet is less likely to flatten out as much as a pure lead bullet leading to dissipation of energy over a larger area. A concentration of the same energy over a smaller area means higher penetration.[/quote]

Steel may be more resistant to lead under stress, but this is not quite as straightforward as it seems. First of all, steel cores used in bullets are not "tool steel," they are soft steel. The steel is not normally treated, as this costs money. Steel cores meant specifically for armor piercing may have alloys that make them able to penetrate more deeply, but this is not the case for normal rounds, where the cost savings of using steel cores is commonly one of the advantages of using this material for bullets. The Soviet Union, for example, used steel core bullets, as well as copper-washed steel jackets in order to conserve copper-based alloys for other war uses. (They used steel cartridge cases for the same reason.)

Lead used in bullet cores is not normally pure lead, such as what is used in muzzle loading weapons, either, and the lead is coated with a copper alloy jacket (or steel) which gives rigidity to the bullet, as well.

Early French Lebel ammunition used bronze as a bullet material and some hunting bullets that are meant for deep penetration of tough game also are solid, without the use of lead. However, on the other hand, US A10 attack aircraft used a special 30mm cannon using rounds with bullets made of cores of depleted uranium, giving even greater density and energy retention for punching holes in armored vehicles on the battlefield.

This subject is more complex that is being presented and the issues involved are hardly worthy of blithe dismissal as irrelevant.

[bennedose]

Actually I saw a link yesterday (specs for Indian Army Bulletproof jackets) that puts the weight of the INSAS bullet at 3.5 to 3.75 grams which is at least 0.25 to 0.6 grams lighter than the NATO standard (4 to 4.1 grams).

I have seen no information to suggest that the INSAS bullet is significantly longer. The NATO round is 23 mm long. The OFB specs put he steel core bullet as 24.5 mm. But the OFB site put the bullet weight as 4.16 grams - marginally heavier by 6 milligrams

The links and quotes below.


Relevant links:
Fom Google Cache

DESIGN PARAMETERS FOR BP JACKETS
A.
Shall confirm to NIJ Standard 0101.06, “Ballistic Resistance of Body Armor,”
Protection against all of the following ammunitions fired from weapons
mentioned against each:
(i)
9x19 mm cartridge fired through Sub Machine Gun (Such as Sten
Machine, MP-5, Carbine, any other variant) from a distance of 5 meters to
achieve a muzzle velocity 430 ± 15m/s and the weight of the bullet
between 7.4 gm to 8.2 gm.
(ii)
7.62x51mm cartridge NATO ball ammunitions fired through 7.62mm
SLR/Bolt action rifle from a distance of 10 meters to achieve a muzzle
velocity 838 ± 15m/s and the weight of the bullet 9.4 gm to 9.6 gm.
(iii)
7.62 x 39mm (mild steel core bullet) cartridge fired through AK series
rifles from a distance of 10 meters to achieve a muzzle velocity 715 ±
15m/s and the weight of the bullet 7.45 gm to 8.05 gm.
(iv)
7.62 x 39mm (hard steel core bullet) cartridge fired through AK series
rifles from a distance of 10 meters to achieve a muzzle velocity 600 ±
15m/s and the weight of the bullet 7.45 gm to 8.05 gm.
(v)
5.56 x 45mm Ball MK M (Equivalent to 5.56 mm NATO (M 193)) cartridge
fired through INSAS rifles from a distance of 10 meters to achieve a
muzzle velocity 950 ± 15m/s and the weight of the bullet 3.55 gm to 3.75
gm

NATO round specs:
en.wikipedia.org/wiki/5.56×45mm_NATO

4 to 4.1 grams

http://ofbindia.gov.in/products/data/am ... n/sc/1.htm

BUllet mass 4.16 grams

http://www.inetres.com/gp/military/infa ... _ammo.html

[TwoRivers]

Early French Lebel ammunition used bronze as a bullet material ...

While "bronze" is often stated, the Balle D material was not bronze, but "high-copper brass", i.e. "gilding metal" in US terms.

[timmy]

Lead is 50% denser than steel. This is a scientific fact.

4.1g is 17% heavier than 3.5g

4.1g is 9% heavier than 3.75g

These two points are mathematical fact.

I observe:

1. If you are comparing bullet weights of a 4.1g NATO bullet to a 4.16g Indian bullet, we can state conclusions. If you are comparing a 4.1g NATO bullet to a 3.5g Indian bullet, we can state conclusions. If we are comparing a 4.1g NATO bullet to a 3.75g Indian bullet, we can state conclusions. In order for any point to be made, we really need to know what bullet you are comparing the NATO bullet to.

2. If the lead core bullet is to weigh the same as the steel core bullet, the steel core bullet is going to have to have a volume that is large enough to account for the 50% difference in density. Either it is longer, or has a significant different shape, or something is amiss.

3. I am therefore lost and cannot understand what point you are trying to make, but I haven't seen anything concrete put forward to justify the notion that a steel core .223 bullet is going to have a greater energy than a lead core .223 bullet.

[bennedose]

3. I am therefore lost and cannot understand what point you are trying to make, but I haven't seen anything concrete put forward to justify the notion that a steel core .223 bullet is going to have a greater energy than a lead core .223 bullet.

I am not surprised at all. I never stated that I was providing facts for you or anyone else to understand. Until we know the exact observations and measurements made in tests - everything else remains idle pseudo-scientifc speculation, which you happened to join midway

All that I have tried to say is what I have heard or read (without being able to provide absolute scientific proof of why things were said to be what they are)

Let me summarize the points that led up to this idle speculation

• 1. I heard that the Indian army complained about the range (or was it power) of INSAS rounds which led to a change in the ammunition specs
  2. The INSAS is reputed to be accurate at long ranges (with no information on what long means)
  3. The Indian army seems to use rounds that are not exactly NATO standard

It was these there data points in my mind that led to my search for more information. It is fine to argue using science or speculation about the information that I found or to say that it is credible or incredible. But I can do nothing to change what I have heard or what I have dug up as reports or references. I can only speculate. If you or anyone else can go beyond speculation I would be happy to read about it. Up until now I have heard only more speculation about the data regarding INSAS rounds that I have heard.

[timmy]

3. I am therefore lost and cannot understand what point you are trying to make, but I haven't seen anything concrete put forward to justify the notion that a steel core .223 bullet is going to have a greater energy than a lead core .223 bullet.

I am not surprised at all. I never stated that I was providing facts for you or anyone else to understand. Until we know the exact observations and measurements made in tests - everything else remains idle pseudo-scientifc speculation, which you happened to join midway

All that I have tried to say is what I have heard or read (without being able to provide absolute scientific proof of why things were said to be what they are)

Let me summarize the points that led up to this idle speculation

• 1. I heard that the Indian army complained about the range (or was it power) of INSAS rounds which led to a change in the ammunition specs
  2. The INSAS is reputed to be accurate at long ranges (with no information on what long means)
  3. The Indian army seems to use rounds that are not exactly NATO standard

It was these there data points in my mind that led to my search for more information. It is fine to argue using science or speculation about the information that I found or to say that it is credible or incredible. But I can do nothing to change what I have heard or what I have dug up as reports or references. I can only speculate. If you or anyone else can go beyond speculation I would be happy to read about it. Up until now I have heard only more speculation about the data regarding INSAS rounds that I have heard.

This is all well and good, but I will not accept your claim that I am speculating. I offered facts about what densities are for lead and steel, and also compared the weights that you provided. This doesn't constitute speculation on my part.

[bennedose]

Something is definitely amiss in the cut in stone opinions I read about the INSAS and since I hear two contradicting versions - there is definitely some speculation going around. Whether any specific person is guilty of speculation is moot.

[ckkalyan]

timmy: Lead used in bullet cores is not normally pure lead, such as what is used in muzzle loading weapons, either, and the lead is coated with a copper alloy jacket (or steel) which gives rigidity to the bullet, as well.

There are lead bullets (pure lead) and 'lead bullets' (lead alloy)! Cast ones are harder and tend to flatten out less. Here is a whole bunch of information: http://www.lasc.us/castbulletalloy.htm

hickok45 has some interesting information, worth watching.

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[estousandy]

2. The INSAS is reputed to be accurate at long ranges (with no information on what long means)

Just to plug something in only about the quote above, especially the bullet stability at long range w/o going into barrel precision or anything related. All this data below happens to come from a thread run by a bloke who is always down for anything Indian made(Good or bad). http://defenceforumindia.com/forum/indi ... post732241

About the twist rate...

As a rule of thumb
40gr likes 1:12
55gr likes 1:9
77gr likes 1:7

If you-plan-on doing some-prairie-dog hunting and need light, zippy rounds then a 1:12 is probably best instead. It will still stabilize some of the heavier stuff (like 55gr) to a degree, but not for very far.

If you’re on the other end of the spectrum and long range accuracy is your kind of thing, then 1:7 is the twist rate to go with. Heavier (and therefore longer) bullets are more-resistant-to external factors and have more mass, which means they maintain velocity longer and are accurate at longer ranges. In other words, ideal for long distance shots.

1:7 will stabilize the biggest bullets you can cram in the case and do it well, but it will also stabilize the lighter stuff (like 55gr).

Seeing this, the INSAS(running 64-77gr ammo) with 1:7.8 twist barrel does appear to be more orientated to long range shooting than to CQB, which would explain why the IA prefers the AK series for CT ops. Of course the IA could theoretically also go for 1:14" barrels and 77gr rounds for absolute devastation(from tumbling) on short range encounters.

[estousandy]

Can't fight maoists with INSAS in jungles

For some reason, text on screen says more than what the trooper says.

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[nagarifle]

INSAS it would appear to me who is a self confessed armchair commando, to be a bucket of emotional cra^ .

why not ask the jewan if he wants INSAS OR A AK?
why not ask the VIPs if they want to INSAS or a phooran gun to guard them.

the humble JEWAN has to be loyal to his country, even if it kills him.

[estousandy]

Why is govt lax on phasing out INSAS? HC

http://timesofindia.indiatimes.com/indi ... 022266.cms

NEW DELHI: The Delhi high court on Wednesday asked ministry of defence to reply to a PIL which has alleged that the Centre has been lax in phasing out Indian Small Arms System (INSAS) rifles despite being aware defects in the weaponry, leading to avoidable deaths of soldiers and paramilitary troopers.

The PIL which was filed by a retired Army officer points out even the replacement, AK - 47, is an effective and a cheaper alternative but the government has continued with INSAS rifles.

Taking a serious note of the matter, a bench of Chief Justice G Rohini and Justice Rajiv Sahai Endlaw demanded an explanation from the ministry of defence on Wednesday.

The court asked the ministry to explain why it has not replaced the outdated INSAS rifles with modern fire arm for soldiers and gave it time till 8th July. "You introduce new fighter planes time and again, why are you not thinking on this aspect? The government should do something for these people (military and paramilitary personnel using INSAS)," the bench remarked.

Lt Col (retd) Deepak Malhotra, the petitioner, alleged that because of "bureaucratic red tape" soldiers are made to use a "clearly inferior weapon" at the "risk of losing their lives".

He added that elite Army units have rejected INSAS and said that plans to replace them are pending in the desks of Home and Defence Ministries.

"The defect in these rifles has been known to authorities since long but because of bureaucratic red tape the jawans are made to make do with a clearly inferior weapon at the risk of losing their life," the petition alleged, seeking a direction to the MoD to immediately withdraw INSAS rifles from active service and replace with suitably modern firearm in a time bound manner. It petition also urged the high court to issue directions to the MoD to produce the records pertaining to the long pending decision to replace "defective" INSAS rifles.

"Despite knowing, for several years, that the indigenous INSAS assault rifles are of defective design and metallurgy, the bureaucratic system has delayed the replacement of these unreliable assault rifles even though the replacements were actually cheaper than the INSAS. Elite Army Units have rejected these weapons. The rifle malfunctioned in the Kargil War," the plea said.