Norinco is the civvy name for North China Industries, which are manufacters of many Chi-Com small arms in China, such as the SKS (Type-56 carbine, the AK Type-56 rifle and the AK with folding stock, the Type-56-1 rifle.
Your SKS sounds a civvy contract import, as all Chi-Com military rifles bear Chinese characters, and an arsenal stamp, usually marked inside a triange, and numbered say ‘66‘ etc.
On the SKS for example the Chinese characters mean ‘carbine‘, and this can be followed by a 56, as the SKS in China is called a Type 56 carbine.
Military SKS‘s that are Chi-Com have a cruiciform bayonet, and early Chi-Coms have a blade type, but Russian ones have a blade, and Soviet markings. Russian SKSs also have a liminated wood stock, and are all have machined solid stock housings.
Civvy imports too, can have the bayonet, and it can also be without it too.
Early Chi-Coms SKSs have milled housings and later ones are stamped steel.
SKSs normally have a 10rd no-detachabe mag and it was fed from 10rd stripper clips through the top (5rd pinned now with the Cdn gun laws).
Any added scopes is purly a civvy thing, and there is no scope mounts on the SKS.
These weapons are hand fitted, so the gas piston, gas tube, bolt, carrier, and body cover will have the serial number on it, and may be stamped or acid etched by hand. Have a look at the underside of your gas tube.
FYI the SKS was made by the fol countries:
Russia
Poland
Yugoslavia
Bulgaria
East Germany
China; and
North Korea, plus a few others.
Many countries has a slightly different version of the Russian one, say compare the Russian SKS to the Yugoslavian one.
The SKS has been in service since early 1945, and is still very common today in the arsenals of many 3rd world places.
Hope this info helps ya out.
BTW, back in Saskatchewan I used to own two. A Russian 1953, and a Chi-Com Viet Nam pickup with US capture papers (US War Trophy Registration, and South Viet Nam Customs export permit). Captured in 1967 from ‘Charlie‘, and brought back to the USA by a US Army soldier from Billings Montana. I got it from him in 1979.
I sold it to a collector in Regina, who still has it. An interesting rifle, with a shrapnel wound to the bayonet. If only it could talk.
Today, I examined 1 RPG7, 1 RPG2, 3 RPK LARs, and 15 AK rifles, all from Iraq, and out of the 14, 9 were Russian AK-47‘s, 1 was a Russian AKM, 2 were Romanian AKMs, 1 Chi-Com Type 56 rifle, and one Chi-Com Type 56-1, plus 2 Yugo RPKs, and 1 Romanian RPK, plus 1 Romanian PKM belt fed GPMG. All smothered in arabic characters, some rusty, some really nice.
All soon to be de-activated for museum display.
Cheers,
Wes