crudely manufactured, perhaps to increase output from factory
View attachment 26288
it's stamped sheet metal design like most AKMs and current gen AK-203, and yet they riveted the inner guide rails for bolt carrier, perhaps to speed up production or thinking it'll 'strengthen' the build...i mean look at MAG 58's receiver, that too has riveted inner guide rails for bolt carrier, BUT MAG 58 has a thick receiver comprised of side plates and trunnions that has to be riveted for that size of mass production...meanwhile INSAS' receiver plate is barely 1 to 1.5mm thick, typical to AK design, so drilling holes that nearby and riveting a rail PLUS a separate ejector blade (that's typically part of the rail itself, usually heat-treated to strengthen it) on its left side, on a relatively thinner build of receiver...
doesn't seem like ideal thing to me...
as for all standard kalashnikovs of stamped sheet receiver design goes, they spot-weld carrier rails there, that much strength is sufficient and it looks elegant too (do note, aesthetics are everything)
View attachment 26291
notice how visibally thick side plates are here on MAG 58's receiver, those tiny inverted L shaped stripes at centre are bolt carrier rails there, affixed by some heavy riveting, overall entire receiver on MAG 58 is rivet-build, because it works there
i've read on certain youtube comment from some ex-serviceman who got issued INSAS, that riveted sheet metal parts sometimes come loose and also, quality of sheet metal used for receivers is also questionable something like 'pins falling out' (pins holding trigger group parts) ? it could happen if pins are 'digging open' those holes meant for housing trigger parts, as they rotate around that axes formed by pins, you know...hammer goes at least 60 degs, trigger around same degrees when fully pulled, and ~30 deg rotation for sear...so torques from those rotations around might be gradually digging out receiver holes that they eventually come loose and 'fall out'...this even happens to some extent on milled receiver designs of non-mil-spec types, reason many civilian AR-15s are given "anti-rotation pins" - an additional holder that firmly keeps pins in place so they don't dig open those holes
(next point, assuming it's 1mm thickness receiver, source is that infamous 'technical treatise' on INSAS at indians for guns phorum) usually some AKM and above modern Kalashnikov pattern rifles have these cross-embossing around pins holes, originally so same trigger parts can be used on milled and stamped receiver AKs by reducing some dimensional differences, but to some extent it provides some additional surface so those pins don't turn/rotate around that easily, but well INSAS most builds i've seen, do not...i'm not sure if they heat-treat those xy-embossed-holes for pins but yeah they eventually realised it's nice thing to do, we did not...if my memory serves right, only Kalantak 'Micro Assault Rifle' (predecessor design to ARDE's 5.56mm Carbine) was given xy-embossed-holes around pins on its receiver...but that remained a prototype level project at maximum
View attachment 26300
now do note this is just one comment i'm talking about above, is perhaps only complaint i read like that so it could be coming from some really poorly made / abused INSAS, but for a military rifle it does have a crudely built receiver...such things should not be happening to start with...
finally, even if you keep 'upgrades' in mind, a receiver is a heart to a firearm's design, you want to bring some significant upgrades, you have to alter it at some point...and unfortunately kalashnikov design is such that to bring any major upgrades there, you have to alter its receiver, or made compromises around that design itself...
that's why we have those "adapters" that goes in standard akm receiver to even house a modern AR pattern buttstock there, because old era holder doesn't work with it, and it's mostly furniture upgrades that one can do on typical Kalashnikov pattern firearms, you can put any high quality railed top-guards that enables mounting of modern optics there, and it'll still have some 'play' there, affecting accuracy at longer distances...
but you replace that kalashnikov style receiver with something else, while keeping major internals same, you can do proper upgrades...imagine an INSAS build that has two-section receiver design, and lower receiver has STANAG pattern magazine well, plus ambidextrous bolt hold open/release, plus ambidextrous push-button type mag releases, and top receiver has rails that doesn't have any 'play' there so better accuracy than before, then you can even attempt at giving some new style of charging handle there, then you can directly put AR buttstock mount at rear side to directly house most modern buttstocks there...and yes aesthetics wise it will definitely better than typical INSAS
^overall a thorough, complete upgrade for INSAS, without much need for those FAB style things
