• Advertisement
Kiehberg.in -  Outdoor gear and sports equipment

The INSAS 5.56mm Rifle- A Technical Treatise

Posts related to rifles.
cottage cheese
Posts: 1425
Joined: Thu Dec 07, 2006 10:15 am
Location: Shillong-Dimapur

The INSAS 5.56mm Rifle- A Technical Treatise

Postby cottage cheese » Fri Mar 12, 2010 12:34 am

Last week I was given an opportunity to fiddle and inspect a bunch of INSAS rifles in detail by the local police.

I thought it'd be a good opportunity to dissect the INSAS and dispel some myths and misconceptions about it.

So with the two line preamble, I take great pleasure in presenting to the gun community, a modest Technical Treatise of the INSAS Rifle 5.56mm 1B1. The specimen in this study was factory fresh and manufactured by the R.F.I (Rifle Factory Ishapore), West Bengal.

To start with, we shall touch up a bit on its pedigree. Common misconceptions of the INSAS's origins and designs range from it being a Galil clone to a hotch-potch of the FAL, M-16, AK & G3... none of these are in-fact entirely accurate.

The evolution of the INSAS, in fact, closely follows the development of FN 5.56mm Rifles/Carbines with an added Kalashnikov flavor to aid cheap and mass production.

I think one can clearly see why the notion of an FAL gas system clone appeared and stuck on. The early developmental versions of the INSAS sported a gas block and fore sight assembly very similar to the FAL and the SLR1A. The Gas plug design is a common to all. However one should remember that the ill fated FN CAL 5.56mm Rifle was a developmental design that included numerous design features from the FAL. Thus in relation to the scale involved (7.62mm to 5.56mm), the more obvious conclusion would be that the early to mid developmental INSAS rifles borrowed the Gas block/plug/Fore sight assembly from the FN CAL...and not the FAL. Thus the FAL influence ends with the prototype INSAS and not the current issue/production version. The picture below, which I cobbled together, was sourced from various net sources- you can see the obvious relations.

http://i207.photobucket.com/albums/bb31 ... _INSAS.jpg

However, since then, they(FN) incorporated a few changes, most probably (as I see) with a view to simplify manufacture. The current FNC is essentially a very simplified FN CAL, with improvements and design elements altered to suit quick and less expensive manufacture. The gas block & fore sight assembly was simplified to be made from simple forgings or investment castings with the minimum possible machining operations. The current production INSAS 1B1 sports a virtual 100% clone of the assembly. Take a look at the picture below for a comparison of the FNC and the INSAS... also note the general similarity of the entire fore end and the muzzle piece.

http://i207.photobucket.com/albums/bb31 ... CINSAS.jpg

The FNC in the above picture is a civilian version with no grenade launching facility or a bayonet lug. Below is a comparison of the muzzle end of the standard military FNC and the INSAS IB1. Note the identical NATO standard 22mm diameter muzzle brakes and grenade launching split rings on both the guns. This seems to be an entirely export oriented feature on the INSAS as I'm not aware of the Indian Army using rifle grenades of this type. The muzzle brake with a radial series of 3 circular ports is common to the INSAS, FNC the CAL and the FAL...

http://i207.photobucket.com/albums/bb31 ... litary.jpg

The gas blockage for grenade launching is achieved by rotating a sheet metal bracket/latch that folds away behind the fore sight post. This is called an "Alidade". Rotation is approximately 90 degrees. This is identical in the FNC and the INSAS. The one on the INSAS is made of a very flimsy half mm sheet... it's actually flimsy enough to deform slightly every time you rotate it. The pictures below illustrate the Alidade in both positions.

http://i207.photobucket.com/albums/bb31 ... 5552-2.jpg

http://i207.photobucket.com/albums/bb31 ... 5553-1.jpg

The top edge of the Alidade has a "v"notch that becomes visible when it is raised to the gas-blocked (grenade launching) position. This can be aligned with a 'foresight' bead on the grenade to 'aim' the projectile. The picture below illustrates the V notch.

http://i207.photobucket.com/albums/bb31 ... C05554.jpg

The Immediate area behind the Gas block & Fore-sight assembly houses a gas regulator (Circled area in image below) It operated in the same way the FNC does but the lug and locking plunger has been shifted to the front. In the FNC this is in an extension of the breech trunnion just above the chamber. It has two positions Low and High. Default setting is Low.(11'oclock as in the picture below)

http://i207.photobucket.com/albums/bb31 ... ulator.jpg

It is commonly believed that the cocking/charging handle of the INSAS is a copy of the H&K G3/HK33/53 series of rifles. The H&K influence goes only as far as the positioning of the cocking handle - i.e. Ahead of the breech, left side 11 o'clock position with the muzzle away from you. In execution, the design is a virtual lift of the charging handle assembly of the 7.62mm SLR 1A. This has been achieved by extending and re-contouring what would have been the rear sight base one the AK/AKM, about 4 inches forward. The 'T'-slots for the cocking slide is machined on to this trunnion extension. In my opinion this seems to have complicated the manufacturing process because of the added machining operations. Also you cannot rotate the cocking handle to lock back like in the H&K rifles. In its rear most position the slide interferes with the opening and closing of the pivoted receiver cover. The picture below illustrates the relationship between the three rifles types.

http://i207.photobucket.com/albums/bb31 ... Handle.jpg

Moving on rearward to the mid section of the INSAS, one can see an unmistakable AKM/Kalashnikov influence. The receiver is of pressed sheet metal of approximately 1mm thickness. It follows the traditional boxy AKM type receiver design with the prominent dimple over the magazine well. The dimple on the INSAS is more angular than that of the AKM. Below is the right hand side of the receiver. With a prominent SLR type carrying handle that's redundant and hardly ever used. Personally, I think this feature is a useless money sink in a 5.56mm rifle. Also missing in the INSAS is the large AK type selector lever. This has been substituted by a virtual clone of the FNC selector lever on the left side of the receiver.

http://i207.photobucket.com/albums/bb31 ... SRight.jpg

Unlike the 7.62mm SLR-1A, the carrying handle in the INSAS is an elaborate spring tensioned type. This greatly increases the number of parts and machining operations for a part that's next to being a useless appendage. See the image below.

http://i207.photobucket.com/albums/bb31 ... Handle.jpg

Below is a picture of the left side of the receiver. Also note how crude the lettering is- looks to be scratched on by hand!!

http://i207.photobucket.com/albums/bb31 ... 5560-1.jpg

The primary difference in the receiver design is with the trigger axis hump in the INSAS. The Trigger mechanism is a virtual copy of the FNC. That being said, the FNC mechanism is very loosely based on that of the Kalashnikov. The FNC trigger mechanism design necessitates a lower trigger axis and thus a greater depth of the receiver. This would however have resulted in an awkwardly bulky receiver. The downward hump probably resulted from this need. The picture below gives an idea of the receiver design and the position of the trigger axis of the three rifles.

http://i207.photobucket.com/albums/bb31 ... SASFNC.jpg

The INSAS 1B1 has three modes- Safe, Semi and 3round Burst. The selector lever is identical in position to that of the FNC and is a well though out adaptation on an AKM type receiver. The design of the thumb piece is based more on the SLR design rather than that of the FNC. However, it is still not as ergonomic as planned and unless you have thumbs like E.T., you'll need relinquish your firm hold on the grip to actuate the selector. Very similar to the SLR, the safety position is top most, down about 70 degrees and you have semi, then to activate the tri-burst mechanism you'll need to rotate it almost 180 degrees. Take a look at the image below.

http://i207.photobucket.com/albums/bb31 ... lector.jpg

The three round burst mechanism is a sheet metal encased module that sits on the left side of the trigger/sear shoulder. It works by way of a ratchet and pawl lock-work. It is a vitual clone of the FNC/CAL module and at least in theory, independent of the basic functioning of the trigger mechanism. i.e. in case it buggers up, semi will continue functioning. The red circle in the picture below shows the 3 round burst module.

http://i207.photobucket.com/albums/bb31 ... 5568-1.jpg

The rear sights on the INSAS are a generic two position peep type with windage adjustment. This is housed in an investment cast cradle with typical rounded protective ears. The windage adjustment is effected by a knurled windage knob one the left side, and is held in position by a spring loaded plunger on the bottom. A short 3 inch dovetail rail on the top of the receiver ahead of the rear sight assembly serves as a 0.5" interface for mounting scopes and other optical sights. The images below show a detail view of the rear sight assembly.

http://i207.photobucket.com/albums/bb31 ... C05557.jpg

http://i207.photobucket.com/albums/bb31 ... C05558.jpg

http://i207.photobucket.com/albums/bb31 ... C05559.jpg

Also note that unlike the AKMs the INSAS makes extensive usage of rivets. The inner receiver rails(race ways for the bolt) are also riveted on rather than spot welded.

Field stripping is very similar to the AK, albeit ,with some needless complications....no doubt adding to the cost of the rifle. Like any other weapon, ensure that it is indeed empty and there is no round chambered and that the magazine is removed. Cycle the action and visually eyeball the chamber. The cycling action is very scratchy and uneven. Many specimens bind for no apparent reason while manually cycling the action.
The blue circle in the picture below shows the standard AK type receiver cover locking stud. But you can't simply operate it like a normal AK... you'll have to first press the lock out button (red circle) which is usually very badly fitted and stiff. You'll be able to get the AK type stud moving only when you do so. I can't think of any reason why this unnecessary feature was included....another money sink. Also note in this and earlier pictures, the re-enforcing cap in the rear end of the receiver cover. This is usually a very poorly formed and fitted piece.

http://i207.photobucket.com/albums/bb31 ... erlock.jpg

Once you've got through hurdle of the locking stud, simply lift the cover. It is captive (i.e. remains on the gun) and pivots upwards like the AK74U. The receiver cover is attached to the pivot by a trio of rivets and this joint may be critical to the long term accuracy of the rifle as the rear sights are mounted on the receiver cover. Often this is badly fitted, often bearing on the trunnion locking shoulder. This either results in bent receiver covers or big gaps in the area.
See picture below and take note of the poor plastic to metal fit.

http://i207.photobucket.com/albums/bb31 ... C05566.jpg

Once you've done this, push the recoil spring guide rod forward, up and rearward. Then pull back and up, the bolt carrier/ piston assembly.

The bolt carrier and bolt is an AK clone scaled to suit the 5.56mm cartridge take a look at the picture below.

http://i207.photobucket.com/albums/bb31 ... C05567.jpg

Next, you remove the upper hand guard. This is a flimsy piece of plastic thats always getting lost or breaking in two. The front end has 'PULL' embossed on it and you simply grasp the projections on the front end and ...well...pull.
It has two pairs of rounded steel spring tongues that simply clamp over the gas tube. Its either too tight or too loose... both with individual headaches - too tight and the plastic usually breaks, too loose, it usually gets lost or rattles and dances all over the place.

http://i207.photobucket.com/albums/bb31 ... C05555.jpg

http://i207.photobucket.com/albums/bb31 ... C05556.jpg

Once this is out of the way and hopefully you haven't broken the hand guard, you now prepare to remove the gas cylinder. The short gas cylinder is retained in the trunnion extension by a very AK flavored latch... which is often too tight. Many rifles have poorly fitted gas cylinders that really prevents the half-cut cross pin and thus prevents the locking latch from closing smoothly. I saw five brand new broken examples. One was missing the latch.

http://i207.photobucket.com/albums/bb31 ... C05569.jpg

Above- The gas tube retaining latch in open position. Note that the Lower hand guard is a direct lift of the CAL/FNC design albeit with an AKM type retaining interface.

Below- The gas tube removed.

http://i207.photobucket.com/albums/bb31 ... C05570.jpg

Now you've stripped the blasted gun!

Below- The INSAS basic field strip.

http://i207.photobucket.com/albums/bb31 ... 5571-1.jpg

Here's the INSAS with its basic complement of three magazines. 20x3=60 rounds.... er that's just 10 rounds more than what our fathers and grand fathers carried with their 303's into battle 40-50 years ago. This on the whole negates the whole idea of an automatic weapon...

http://i207.photobucket.com/albums/bb31 ... C05573.jpg

A pair of Steyr AUG inspired waffle ribbed transparent magazines.

http://i207.photobucket.com/albums/bb31 ... C05574.jpg

My camera doesn't have decent macro...so I couldn't photograph the cartridge head stamps. Anyway the fodder below is KF 5.56mm....

http://i207.photobucket.com/albums/bb31 ... C05577.jpg

Here's how the magazines come packed from the factory.

http://i207.photobucket.com/albums/bb31 ... C05575.jpg

I noted at least three different manufacturers of INSAS magazines, and goodness are they flimsy. I recognized at least one of the sub-manufacturers for magazines - Nilkamal - One of the well known names in plastic furniture.

There were several INSAS rifles made by SAF(Small Arms Factory) Kanpur- They exhibited several badly fitted parts.
Take a look at the picture below. The upper one is and RFI made INSAS and the one in the bottom is an SAF specimen. The RFI rifles appear to be zinc phosphated as they sport a very light grey finish while SAF INSAS rifles are darker and presumably iron or manganese phosphate finish. Take note of the white splotches on the SAF rifle- I noticed all the SAF rifles had these. I found out that they wanted to have white paint filled lettering, but the crude scratching that passed off as lettering was too shallow and the lazy buggers at the factory simply squished some white enamel over the general areas and didn't even bother to wipe off the excess!!

http://i207.photobucket.com/albums/bb31 ... C05578.jpg

Over all the INSAS rifle is a major disappointment and while this study is purely academic and has no bearing on the end user, I think it's all I've been calling it all these years- An over weight, complicated, over priced, mediocre rifle.

In the end it shoots- fairly accurately and with reasonable reliability but its plagued by shitty quality and needless refinements of dubious value.

Bottom line - we could have done so much better.

For the shooting report- Check the threads that carry Jonah and Devs reports.

You do not have the required permissions to view the files attached to this post.

He who can not think, is a fool; he who will not, a bigot; he who dare not - a slave!

For Advertising mail webmaster
Posts: 143
Joined: Mon Nov 16, 2009 1:02 am
Location: pune

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby lionheartguru » Fri Mar 12, 2010 12:45 am

usefull information
thanks for sharing it buddy

Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

Vassili Zaitsev
Posts: 115
Joined: Fri Dec 04, 2009 2:13 am
Location: Mumbai

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby Vassili Zaitsev » Fri Mar 12, 2010 1:13 am


"Everything that has a beginning, has an end !!!"

User avatar
Posts: 1805
Joined: Tue Dec 05, 2006 11:50 am
Location: Kolkata

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby TC » Fri Mar 12, 2010 3:51 am

As a journalist I had the opportunity to cover the ceremony at Ishapore in 1993 when the first batch of 1500 INSAS rifles was officially handed over to the army. Maj Gen Kahlon from the College of Combat, MHOW, received the rifles. It was some kind of historic moment for the engineers who worked hard on the first three prototypes. And IOF was looking forward to the big bulk order once the army approved of the weapon. To me the rifle's apparent similarity to the AK and Galil was striking but not unexpected. The army those days was grabbing every AK seized from militants in Kashmir and, at the slightest opportunity, using them against the enemy. Surely, they were tired of the FAL in ambush and CQB.
At the ceremony Maj Gen Kahlon told me two things that went into my newsreport (I was in The Statesman those days). One, the army wanted a short and light weapon with greater firepower, which the INSAS promised on paper.
Two, although the priority was on R&D the defence ministry would have to consider the cost factor because IOF would be forced to keep the price of EACH Insas to around Rs 15,000 to cover averhead costs whereas a certain East European vendor had (then) just quoted around 100 US dollars for one AK (a variant). China was ready to sell its Type 56 for around 90 USD. Those days a USD was equal to Rs 20 (or Rs 22 maybe) if my memory doesnt fail me.
This is a very well researched article. Took me through a bout of nostalgia. Thank you. Just wanted to share some memory with my friends at IFJ which I rarely manage to visit these days.

Posts: 2936
Joined: Wed May 31, 2006 7:28 pm
Location: US

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby ngrewal » Fri Mar 12, 2010 6:07 am


What a great write up thanks for the analysis ... coincidently today I was discussing this gun with nagarifle and his verdict was 'crap' what a crap shoot by babus as TC pointed out $100 cost to allow the jawans field this pea shooter.

Read some where Jawans need a simple rugged consistently reliable weapon like the good old SMLE or FN SLR just like the personality of the jawans themselves. This is neither here or there atleast they should use better quality control and parts where is the pride in work? I am not a fan of AK but lets get those then compared to these...


cottage cheese
Posts: 1425
Joined: Thu Dec 07, 2006 10:15 am
Location: Shillong-Dimapur

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby cottage cheese » Fri Mar 12, 2010 8:59 am

TC wrote:Two, although the priority was on R&D the defence ministry would have to consider the cost factor because IOF would be forced to keep the price of EACH Insas to around Rs 15,000 to cover averhead costs whereas a certain East European vendor had (then) just quoted around 100 US dollars for one AK (a variant). China was ready to sell its Type 56 for around 90 USD. Those days a USD was equal to Rs 20 (or Rs 22 maybe) if my memory doesnt fail me.

Hi TC,

Thanks for the input... after all the bakwaas by the babus... last I heard, the INSAS costs a non military buyer about 23K... Romanian AKs (Erstwhile East German MPiKM an MPiKMS72's) around the time span you mentioned, were imported for the military at a ridiculous $65 each!!
While the IOFB was peddling their SLR for about 24k to non military users at that time... Damn babus.


He who can not think, is a fool; he who will not, a bigot; he who dare not - a slave!

Posts: 344
Joined: Wed Feb 17, 2010 11:34 pm
Location: New Delhi

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby gverma » Fri Mar 12, 2010 9:06 am

Thanks for sharing this rather cool information

Posts: 112
Joined: Fri Jul 27, 2007 8:17 pm
Location: Assam

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby veejosh » Fri Mar 12, 2010 10:54 am

Very enlightining writeup.Thanks CC.The OVERHEADS are the Babus. :(


User avatar
Posts: 101
Joined: Thu Sep 10, 2009 6:54 pm
Location: lucknow

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby brijendra » Fri Mar 12, 2010 11:03 am

amazing write up and info on the insas ..thanx :cheers:

DARWIN said " survival of the fittest "
I say " survival of the armed ones "

User avatar
Posts: 871
Joined: Tue May 23, 2006 10:25 pm
Location: Aizawl

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby jonahpach » Fri Mar 12, 2010 11:15 am

Great stuff CC..

To add to the soldiers misery, any soldier who breaks the magazine or the plastic furniture is required to pay up for the cost from his own paycheck! Looks like OFB is not interested in getting their state-of-the art rifle deployed as the soldiers are too scared to damage it! They have a tendency to break even with a minor accident such as when it slips while stood up against a wall..

Here's a test fire video from my previous post..


Speak softly and carry a big gun!

Posts: 324
Joined: Tue Oct 07, 2008 11:18 pm
Location: bangalore

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby lazybones » Fri Mar 12, 2010 12:23 pm

CC: You are hereby awarded a PhD from the venerable and ancient Mungher School of Gunsmithing
(our motto: "What ever IOF can do we can do better"). :D
A superb study and the next best thing to handling it. I'm certain our babus are going to pinch your article and turn it into their training manual :)
One question though; why is the furniture so bloody atrocious ? I wince every time I see it.


User avatar
Posts: 3379
Joined: Sat Oct 06, 2007 1:43 pm
Location: The Land of the Nagas

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby nagarifle » Fri Mar 12, 2010 12:36 pm

nice work CC, well laid out and thought out. shame that you think our home grown produce are crap, rather unpatriotic don't you think? what would the outsiders think? have you no shame? you should have said something nice, like the army chaps who do not condemn the INSAS but go ahead and buy AK from outside. i won't give my piece of mind now but wait until i meet you, then i will buy you a pint. opps we live in a dry state. :D


if you say it can not be done, then you are right, for you, it can not be done.

User avatar
Posts: 1805
Joined: Tue Dec 05, 2006 11:50 am
Location: Kolkata

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby TC » Sat Mar 13, 2010 12:44 am

Hi CC, nice to hear from you after almost a year...or maybe more. A great writeup indeed.

Hi friends,
If you ask me babudom has killed modern India. I often feel when the Brits left they wanted to leave something that would again take India back by 200 years. So they left the babus.
Look at the hanky panky over allocation of 3G spectrum licence to private cellular operators. When the world has moved from 3G to 3.5G to 4G we are stuck with 2G. (Sorry moderator I am not starting a discussion on 3G. This is just an example).
Would anyone believe that a country which produces ballistic missiles, satellites, tanks, planes and APVs cannot put together a rifle or a decent pistol ?
I know some guys in MOD. One of them told me that at the heavy vehicles plant in Jabalpur they once started making iron buckets ( the common balti i.e.) because the men had no work for months and were being paid for idle hours !!!!!
Liked the video. Didnt know they had made a brass catcher for INSAS. I shot the rifle several times...even at the border after Kargil...kept wishing it did not blow up on my face...the 50 metre groups werent too bad though..that sums up I guess.
Take care guys.

PS: Saw a thread on online sale of G Smith crossbows. Want to get one for myself. If anyone have used these KINDLY PM me. PLEASE do not use this thread. Thanks.

User avatar
Posts: 4407
Joined: Fri Jun 02, 2006 6:14 am
Location: Tbilisi,Georgia

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby Vikram » Sat Mar 13, 2010 7:07 am


I take my hat off to you for putting up this amazingly detailed and insightful study.Thank you very much for the efforts you have invested into this post.If only those whose job is to create and produce these rifles had a fraction of your intellect and dedication,things would have been much much better. :cheers:

TC,good to see you posting after a long time.Welcome back.


It ain’t over ’til it’s over! "Rocky,Rocky,Rocky....."

Posts: 2936
Joined: Wed May 31, 2006 7:28 pm
Location: US

Re: The INSAS 5.56mm Rifle- A Technical Treatise

Postby ngrewal » Sat Mar 13, 2010 7:26 am

nagarifle wrote:nice work CC, well laid out and thought out. shame that you think our home grown produce are crap, rather unpatriotic don't you think? what would the outsiders think? have you no shame? you should have said something nice,e. :D

Believe there are jingos out there who believe that INSAS is great at its price range compared to purchasing Rs1 Lakh a gun! ( not sure how this cost was estimated) but blind chauvinism leads to blinkers. Even Toys r us have better finishing for plastic toys. Great work CC

TC do post often and yes I know thing or two about Jabalpur factory my father conducted audit for it what a big hole..


Return to “Rifles”

Who is online

Users browsing this forum: No registered users and 20 guests