Question on Lightening Cuts

[Larry D.]

I've had a few random thoughts about this in the past....

We're not talking about a whole lot of weight here. Not really enough to be appreciable, anyway.

I understand that ounces count. Especially when it translates into the amount of extra ammo you could carry. Since the SKS is not a select fire, or auto for that matter, so it wouldn't increase the rate of fire in any appreciable manner.

HOWEVER! Commies have not been known to be overly responsive to the needs of the foot soldier.

My thought is that they did it in order to reclaim/reuse/recycle the metal shaved off for other purposes. I believe the Russians did this with the capture screws from captured K98's.

What says the gallery?

[Justin Hell]

I always wondered about this, and generally settled on shaving off a little metal of such little consequence to be for weight savings. The amount of weight loss vs more crap to clean out of nooks and crannies that were unnecessary, and the potential for corrosion as a result in places that could be cleaned with mom's spit thumb. It probably was'nt conservation of metal, so much as something that eased the machining process....or assembly process, if you consider the rear sight block evolution on Russians as part of what is considered.... 'lightening'.

I also considered it seems to make more sense to serial where the lightening cuts on the bolt carrier are as seen on Yugos.
That I suspect is why bolt carriers on early Russians have what has become to be known as 'lightening cuts' yet the front sight blocks do not, but later Russian FSBs DO.   Don't call it testimony, but I seem to recall seeing some photos on Russian websites of very early SKSs having serials in the carrier cut. It may have become apparent that if scrubbing and reserialling was to be done down the line...the carrier's serial just got moved to the standard location for ease alone. It could be the machining and/or supply of carriers never changed...athough the carrier cut seems to be a separate action, that is the most imprecise machining on ANY variation.....seems like an annoying PITA to me, if it wasn't for a reason....

On the front sight block lightening cuts, the only thing I can think of is that it might be for seating the tools, possibly developed, or refined later for adjusting the front sight to have a spot to bite into. Both the Chinese and Russians have those fancy tools like P32 has...perhaps he can ring in on whether it seems those would assist in their use.

Overall, I don't think weight was as much of a factor in some of it...perhaps metal savings, but I think it might just be a combination of factors related to each part that we consider under the umbrella of lightening, that are all done for different reasons. China may have skipped the bolt carriers from the beginning had they not had metric butt tons of Russian parts to use.

[Greasemonkey]

Just to throw it out, like carrier and bolt lightening cuts, what if it's a reliability measure. Maybe just simple physics... it takes X amount of force to move X amount of weight, just a small amount, a few grams could change the force or pressure needed to cycle it and affect the speed at which it cycles. Also, a few grams less weight could help the recoil spring live a little longer after numerous rounds.  I'm sure there is quite a bit of variance in recoil spring pressures between new, used and whooped, and probably even country of origin. Different base spring materials, temper, and heat treatment, I'm sure no one made exactly the same spring.

[running-man]

Just to throw it out, like carrier and bolt lightening cuts, what if it's a reliability measure. Maybe just simple physics... it takes X amount of force to move X amount of weight, just a small amount, a few grams could change the force or pressure needed to cycle it and affect the speed at which it cycles. Also, a few grams less weight could help the recoil spring live a little longer after numerous rounds.  I'm sure there is quite a bit of variance in recoil spring pressures between new, used and whooped, and probably even country of origin. Different base spring materials, temper, and heat treatment, I'm sure no one made exactly the same spring.

This was always my line of thought, though Justin has a good point with it possibly being some kind of ease of manufacturability feature.  The cuts themselves are certainly crudely machined, so I always assumed it was simply to get that material out of there.   

Honestly though, I don't think anyone has really ever put a great deal of effort into figuring out what those are truly for.  Maybe the term 'lightening cuts' is a misnomer since those cuts could easily be 'friction reducing cuts', 'ease of manufacturability cuts', or 'increased reliability cuts'. 

[Greatguns]

Just to throw it out, like carrier and bolt lightening cuts, what if it's a reliability measure. Maybe just simple physics... it takes X amount of force to move X amount of weight, just a small amount, a few grams could change the force or pressure needed to cycle it and affect the speed at which it cycles. Also, a few grams less weight could help the recoil spring live a little longer after numerous rounds.  I'm sure there is quite a bit of variance in recoil spring pressures between new, used and whooped, and probably even country of origin. Different base spring materials, temper, and heat treatment, I'm sure no one made exactly the same spring.

This was always my line of thought, though Justin has a good point with it possibly being some kind of ease of manufacturability feature.  The cuts themselves are certainly crudely machined, so I always assumed it was simply to get that material out of there.   

Honestly though, I don't think anyone has really ever put a great deal of effort into figuring out what those are truly for.  Maybe the term 'lightening cuts' is a misnomer since those cuts could easily be 'friction reducing cuts', 'ease of manufacturability cuts', or 'increased reliability cuts'. 

I would agree that it is more than likely an engineering thing more than a weight or save metal thing. If weight was in play then it was probably more on the line of reducing friction than lightening the firearm.

[firstchoice]

Just a thought after reading the thread, was there a weight requirement from "whatever Russian government agency" that required the firearm to be under a certain weight? And how close under that weight did the SKS come in it's original debut? Maybe it was an original design, because of that requirement, that was repeated for all those years because no one dared to change it? Sounds dumb, but then so do a lot of things in history.   

Not saying with any confidence that this is the actual reason. Just saying it could be something mundane like that that was repeated and reasoning was lost to history? Just a crazy thought from an old geezer...

firstchoice

[Bubbazinetti]

I'm thinking more along the lines of reliability,such as in the field under muddy conditions or to help in subartic conditions to prevent the action from freezing up solid.Dunno for sure though but I've seen features in other weapons that were similar.

[firstchoice]

After thinking more on my weight guess, I don't see how the lightening cuts add up to being enough to make any appreciable difference on overall weight. It may have been done as a goal for removing weight to begin with but surely they figured it out later on. Too much machine time and hassle for any reduced weight benefit. 

Bubbazinetti, you may have something on the surface area on the bolt carrier. Less surface to contact for freezing up problems in the cold areas like Siberia. I have no idea about the FSB cuts other than the tooling ideas already mentioned. I thought about pin length, (to be able to use the same length pin for both pins needed on the FSB), but the cuts don't seem to make any difference on pin length.  x2 

firstchoice

[Boris Badinov]

It may have had nothing to do with removing weight. Most of the Chinese guns dont have the carrier cuts, afterall.

The oblong machine cuts on the carriers may have been braze-on location or somehow functional in lathing or machining the carriers themselves- similar to suggestions about the holes in the receiver covers.