An SPR is a Special Purpose Rifle. SPRs are multi-role rifles that can be used for direct combat engagements and CQB, while also being capable of long range accuracy for expedient sniper/counter sniper operation. SPRs are chambered in a main combat caliber like 5.56mm, have an intermediate/mid-range scope (1.1-8x, 1.5-6x, 1.8-10x, 2.5-8x, 2.5-10x, 3.5-10x, you get the idea..) designed to be used at intermediate ranges of 500-800yds, have a tight twist barrel (1:7 is best, but 1:8 works), and a free-float barrel to help with accuracy. The barrel will ideally be 18", but 16-20" is acceptable. The rifle must be 1MOA or sub-MOA capable. It fills the gap between a standard combat rifle and a dedicated sniper rifle. An example of this rifle is the US Navy Mk12.
standard carbine (top
Mk 12 SPR variant (bottom- note the longer barrel and scope)
A PDW is a Personal Defense Weapon. These are usually smaller submachine guns like the MP5K/MP5K-PDW, KAC-PDW, H&K MP7A1 (
). They have very short barrels and are designed to be compact, concealable, and able to be used inside of very tight quarters, like inside a vehicle. My concept for my PDW is actually going to be a PSD (protective security detail) concept. The rifle will maneuver and feel like a submachine gun. The shorter barrel, high magazine capacity, short sight radius (if I use the Back Up Iron Sights (BUIS) ), lighter weight, and highly maneuverable for use in a vehicle or when clearing rooms in very confined CQB (close-quarter battle) situations.
Knight Arms Co. KAC-PDW