The more I learn the more I remember what I've forgotten.
I just remembered ...
The effect on midrange trajectory (MRT)and maximum point-blank range (MPBR, 5" in this case) by line of sight (LOS) distance over line of bore (LOB)
Definition of terms
midrange trajectory (MRT) Highest point of travel over line of sight (LOS)
maximum point blank range (MPBR) 5" in this case. No more than 2.5" over or under line of sight (LOS) for a total of 5" .
line of bore (LOB) bore of the rifle.
Zero, distance in yards the rifle is zeroed at.
Near field zero (NFZ) Where line of sight first crosses bullet trajectory. More on this handy number later
Sighting in a rifle to maximize the effective range where a dead hold will place an impact no more than 2.5" above or below line of sight is a 5" MPBR. Others may use the term differently or choose a different MPBR depending on size of target, game, or ego.
308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 1.5" over bore, 2650 F/Sec
NFZ 25 yards, MRT @ 119 yards, Zero 210 yards, MPBR 246 yards
308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 3" over bore, 2650 F/Sec
NFZ 46 yards, MRT @ 138 yards, Zero 227 yards, MPBR 259 yards
I'll supply data on request as it's commonly available. It's just numbers, far too many to post here.
I just wanted to show raw data to support the notion that the distance between LOS and LOB does make a difference when calculating MPBR.
Also keep in mind that these numbers are derived from a computer model and real-world results will vary noticeably but it's still a good baseline.
NFZ comes in handy when you don't have a range where you can set a target an arbitrary distance like 227, etc. For me it's just a way to avoid wasting ammunition.
The 308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 1.5" over bore, @ 2650 F/Sec having a NFZ of 25 yards is purely coincidental.
The 308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 3" over bore, @ 2650 F/Sec having an NFZ 46 yards is kind of inconvenient so use 1.3" low at 25 yards (It's in the data)
I was just overthinking ballistics again and thought I'd share. Again, I do not solve unsmooth integrals in my head. I just get into some nerdy crap on occasion.
I just remembered ...
The effect on midrange trajectory (MRT)and maximum point-blank range (MPBR, 5" in this case) by line of sight (LOS) distance over line of bore (LOB)
Definition of terms
midrange trajectory (MRT) Highest point of travel over line of sight (LOS)
maximum point blank range (MPBR) 5" in this case. No more than 2.5" over or under line of sight (LOS) for a total of 5" .
line of bore (LOB) bore of the rifle.
Zero, distance in yards the rifle is zeroed at.
Near field zero (NFZ) Where line of sight first crosses bullet trajectory. More on this handy number later
Sighting in a rifle to maximize the effective range where a dead hold will place an impact no more than 2.5" above or below line of sight is a 5" MPBR. Others may use the term differently or choose a different MPBR depending on size of target, game, or ego.
308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 1.5" over bore, 2650 F/Sec
NFZ 25 yards, MRT @ 119 yards, Zero 210 yards, MPBR 246 yards
308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 3" over bore, 2650 F/Sec
NFZ 46 yards, MRT @ 138 yards, Zero 227 yards, MPBR 259 yards
I'll supply data on request as it's commonly available. It's just numbers, far too many to post here.
I just wanted to show raw data to support the notion that the distance between LOS and LOB does make a difference when calculating MPBR.
Also keep in mind that these numbers are derived from a computer model and real-world results will vary noticeably but it's still a good baseline.
NFZ comes in handy when you don't have a range where you can set a target an arbitrary distance like 227, etc. For me it's just a way to avoid wasting ammunition.
The 308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 1.5" over bore, @ 2650 F/Sec having a NFZ of 25 yards is purely coincidental.
The 308 Winchester (7.62mm NATO), Federal Sierra MatchKing BTHP, 168gr 3" over bore, @ 2650 F/Sec having an NFZ 46 yards is kind of inconvenient so use 1.3" low at 25 yards (It's in the data)
I was just overthinking ballistics again and thought I'd share. Again, I do not solve unsmooth integrals in my head. I just get into some nerdy crap on occasion.
