As far as the Lucznik (Archer) 87 being a "military trainer," it's worth keeping in mind that this rather loose descriptor would include school-related pre-military service programs such as introduction to firearms and shooting. Canadian cadets use air rifles to introduce shooting skills, usually the Daisy 853C, a sub-500 fps single stroke pneumatic. If the Lucznik is a "military trainer," then so too is the Daisy.
It is possible to determine the date of manufacture of the Lucznik 87. After 1967, a letter was used before the serial number to indicate date of manufacture: A – 1967, B – 1968, C – 1969, D – 1970, E – 1971, F – 1972, G – 1973, H – 1974, I – 1975, J – 1976, K – 1977, L – 1978, M – 1979 and N – 1980. The absence of a letter would suggest a pre-1966 air rifle. The 87 model rifle was made from 1956 to 1972, after which it had a name change to Predom-Lucznik. Production ended in 1980.