... The results were a Ka Boom that destroyed the rifle. This SKS had never been used for surplus ammo to my knowledge. I had purchased it new when the first Chinese commercial offerings came into Canada from International Firearms.
These loads were developing close to 60,000 psi. The SKS should have been tested to that range with a blue pill pressure round. Maybe it was or wasn't. Still, the rifle came apart.
...
IMHO the SKS is a fine rifle whose pressures should be limited to original design specs. Once changes are made to the basic components, just about anything can and will go awry.
60k psi is probably too much. All other things being equal a standard issue Russian sks would most probably have survived this pressure without a hiccup. Early Chinese commercial sks rifles were notorious for being all over the map as far as quality was concerned.
Here is an excerpt from an old article by Butch Thompson on Chinese SKS (appeared in 1996 compilation "Practical Gunsmithing"
" It also helps to understand how the guns are made. There are seven manufacturing facilities in China that “make” SKS rifles, but in reality, they are little more than assembly points. Most of their parts come from hundreds of small shops all over China, and almost all have to be fitted at the point of assembly. Good parts are mixed with bad. Some rifles will have good barrels but bad receivers, or it may be the other way around. This is true of all the parts in the rifles.
There is also a lack of uniformity on chrome-lined barrels, ranging from the merely inconsistent to a point that the linings have come out of the rifles. We have even been told of a threaded barrel that was driven into a non-threaded receiver and pinned in place.
The SKS rifles are not only inconsistent in the way they are assembled, the metal used for the parts varies widely, too. Cheap Chinese steel is made the way we did it 100 years ago. China also makes a top-quality steel, but it obviously will not be used in rifles they sell us for $37. To illustrate this point further, we took seven Rockwell hardness tests up and down the same barrel and got seven different readings. I’ve had the same experience with receivers. As we go along, we’ll go a little deeper into the metallurgy of the different parts and how it affects what you’ll be doing to the rifles.
Soft metal is to blame for a majority of problems you will encounter with the SKSs—most commonly, broken extractors followed closely by feeding and ejection failures. Your biggest problem won’t be mechanical—it will be justifying the high cost of professional repairs when you didn’t pay much for the gun.
Your major problem will be getting parts. I have found—and other gunsmiths confirm this—that the ones you will get actually fit less than 20 percent of the time. They can be made to fit only about 70 percent of the time. For this reason, the SKS will show who is a gunsmith and who is a parts exchanger."
Needless to say that none of these problems are present in the Russki rifle