The plastic Poly Vinyl Chloride is commonly abbreviated to PVC. UPVC is Unplasticised Poly Vinyl Chloride and is a rigid form of PVC often used in the building industry as a low-maintenance material.
Well the m stands for model. So its whole meaning is Model 16 Military Rifle. So the 16 is just a model number. So the M4 is a Model 4 Military Rifle and so on and so forth for other rifles. The...