[DarinHudson]

Hello,

I am working on a calculator, and I need to know what the relationship is between MPBR, MRD and GEE... The research I have done thus far indicates that the metrics of MRD and GEE and simular and MPBR is a metric unto itself.. Can anyone tell me if that is indeed the case?... Are some of these measurements simply metric based (opposed to english.. i.e. meters instead of yeard) measurements?..

Where can I find an actual forumula to calculate MRD/GEE when MPBR is known?.. or calculate MRD/GEE when BC,bullet weight and muzzle velocity are known?...

Specifically I am not looking for some place to go and make a calculation.. I am looking to actually see the forumula which needs to be used...

Any help greatly appreciated..

Darin
Grand Island, NE

 

[HarryS]

I think you are using the wrong definition of metric!!!!

These are positions on a ballistic trajectory. Most people paying for a sophisticated program would expect to have the program display these values.

Over my career I've written a number of ballistics software programs. It is just math, remembering that things like BC are just approximations. Even the military (Navy) doesn't have perfect ballistic software. Once you get the program to be close enough for your application, one stops. Bullets (projectiles) are not perfect in flight.

I think of MRD as just mathematically the second zero cross and my software just spits it out.

 

[F2G1D]

Here is the equation for the simple flat fire trajectory. Incorporate the line of sight equation and the desired deviation for MPBR.

Click on page 202 and scroll to equation 8.78.

 

[mr glo]

Welcome to the forum DarinHudson.

I am interested in knowing what kind of ballistics program you are writing. My math kinda sucks so I really can't follow anything you are saying. But it sounds interesting. Would you mine telling me what MPBR, MRD and GEE are or at least the full words. Not that I would be any smarter. But most of the time when I see GEE, some one is referring to me. As in, “Hay GEE ("G") how are you doing.”

Lots of real good information here. Again welcome.

 

[F2G1D]

I'm disappointed. I thought your handle stood for 'Musgo Real Glyce Lime Oil (MR GLO)'.

 

[mr glo]

I'm disappointed. I thought your handle stood for 'Musgo Real Glyce Lime Oil (MR GLO)'.

Say what

Oh too funny... I just googled it. No don't use the stuff I got a beard.

mr glo comes from the fact that glo as a handle wouldn't work here. glo is another nick name I have gotton over the years. I use glo on other forums. glo is short for my last name; Glover. glo is better than this nick name: G Lover.

 

[F2G1D]

MPBR = maximum point blank range

MRD = most recommended distance

GEE = günstigste Einschussentfernung, most favorable zeroing distance

These all basically refer to a distance over which the bullet does not deviate from the line of sight by a specific amount.

 

[DarinHudson]

So here is a question you guys should be able to tell me.. especially F2G1D...

Is GEE a metric version of MPBR?... or is MPBR an old english (i.e. feet & inches) version if GEE?... can you take one of these (either GEE or MPBR) and apply a mathmetic formula to find the other... such as you can take a length in meters multiplied by 1.09361 to get yards. or are MPBR and GEE.. not the same measurements using different units?... it appears as though the calculator I am working with (I inherted the code) tries to make these two numbers (GEE & MPBR) anagulous.

 

[F2G1D]

So here is a question you guys should be able to tell me.. especially F2G1D...

Is GEE a metric version of MPBR?... or is MPBR an old english (i.e. feet & inches) version if GEE?... can you take one of these (either GEE or MPBR) and apply a mathmetic formula to find the other... such as you can take a length in meters multiplied by 1.09361 to get yards. or are MPBR and GEE.. not the same measurements using different units?... it appears as though the calculator I am working with (I inherted the code) tries to make these two numbers (GEE & MPBR) anagulous.

The GEE, identical to MRD, is a metric number describing the range for which the bullet never rises to more than 4 centimeter above the line of sight.

The MPBR is an english number describing the range for which the bullet deviates by no more than 3 inches (not a firm definition) from the line of sight (above or below).

There is no reason that any of these couldn’t be expressed in other units.

 

[broom_jm]

Maximum PBR is the distance at which the projectile crosses more than "x" units of measure below line of sight, whereas the other two seem to be a recommended zeroing distance to obtain the above.

FWIW, most max PBR equations also come with a recommended zeroing distance, for that sight height equation. For example, one would sight in 3.24" high at 100 yards to obtain a 325 yard maximum PBR, for an 8" kill zone, with a 300 WhizBang, with a MV of...blah, blah, blah. These equations also recommend that you zero at a specific yardage, like 238 yards...like people really have some place where they are going to measure out exactly 238 yards and then zero at that range.

 

[F2G1D]

Maximum PBR is the distance at which the projectile crosses more than "x" units of measure below line of sight, whereas the other two seem to be a recommended zeroing distance to obtain the above.

FWIW, most max PBR equations also come with a recommended zeroing distance, for that sight height equation. For example, one would sight in 3.24" high at 100 yards to obtain a 325 yard maximum PBR, for an 8" kill zone, with a 300 WhizBang, with a MV of...blah, blah, blah. These equations also recommend that you zero at a specific yardage, like 238 yards...like people really have some place where they are going to measure out exactly 238 yards and then zero at that range.

Sellier & Bellot - Most recommended distance and shortcuts bottom of page

http://www.ruag.com/de/Ammotec/Hunting_Sports/RWS/RWS_Rifle_Cartridge_Broschure.pdf page 12

MPBR - Maximum Point Blank Range paragraph 2

Alternatively, they may give the 'amount high' at 100 yards.

 

[mr glo]

I guess knowing maximum point blank range (MPBR) is good thing. I would be curious to know how many hunters still use regular and duplex cross hairs for long range hunting.

To me anything over hundred yards for big game is long range. Anything over 300 yards for vermin is long range.

Maybe I'm different as I'm a bird hunter and target shooter, not a big game hunter. Seems to me most folks are buying and using scaled reticle scopes now (mill dot, MOA and the such...). Or using their elevation turret in conjunction with laser range finder. But maybe I'm just fooling myself or out of touch.

 

[F2G1D]

To me anything over hundred yards for big game is long range. Anything over 300 yards for vermin is long range.

Not if you use this!

Bullseye from 1,000 yards: Shooting the $17,000 Linux-powered rifle | Ars Technica

 

[broom_jm]

I guess knowing maximum point blank range (MPBR) is good thing. I would be curious to know how many hunters still use regular and duplex cross hairs for long range hunting.

To me anything over hundred yards for big game is long range. Anything over 300 yards for vermin is long range.

Maybe I'm different as I'm a bird hunter and target shooter, not a big game hunter. Seems to me most folks are buying and using scaled reticle scopes now (mill dot, MOA and the such...). Or using their elevation turret in conjunction with laser range finder. But maybe I'm just fooling myself or out of touch.

You aren't out of touch; your thoughts on Max PBR are totally in-line with the majority of big-game hunters in this country. Contrary to what a handful of shows are portraying, most folks look at this almost exactly the way you do. In fact, the average shot taken on big game animals in this country comes right around 100 yards, give or take a little. Out West it's more and in the thickets of the South and Northeast, it can be half that, but suffice to say that the percentage of big game taken beyond the MPBR of the firearm with which it was harvested is very small.

More and more guys are capable of it, and it's certainly a hot topic, but the truth of the matter is that the guys out there looking for long-range shot opportunities on big game are few and far between. Some might call them glory hounds, but I just say that they are introducing a challenge to make the hunt more interesting, to them. Be that as it may, most hunters take the first good shot they get on an animal that they will be happy with. By and large, those shots come at quite reasonable distances; usually well within Max PBR.

 

[F2G1D]

You aren't out of touch; your thoughts on Max PBR are totally in-line with the majority of big-game hunters in this country. Contrary to what a handful of shows are portraying, most folks look at this almost exactly the way you do. In fact, the average shot taken on big game animals in this country comes right around 100 yards, give or take a little. Out West it's more and in the thickets of the South and Northeast, it can be half that, but suffice to say that the percentage of big game taken beyond the MPBR of the firearm with which it was harvested is very small.

More and more guys are capable of it, and it's certainly a hot topic, but the truth of the matter is that the guys out there looking for long-range shot opportunities on big game are few and far between. Some might call them glory hounds, but I just say that they are introducing a challenge to make the hunt more interesting, to them. Be that as it may, most hunters take the first good shot they get on an animal that they will be happy with. By and large, those shots come at quite reasonable distances; usually well within Max PBR.

Don't forget that none of these definitions take group size into account. They are not guarantees of a successful shot.

 

[unclenick]

Jeff Cooper had us either zero at 200 yards or hit 2" high at 100 yards with all high power rifles. We just assumed about 230 yards to maximum. His point was that for combat that approach kept you in a 4" circle to MPBR if the gun and shooter performed perfectly. But you only needed to be able stay inside a 8" circle for a combat size kill zone, so that system actually allows the shooter and other error sources to add as much error as the trajectory path did. He then stayed with that system for hunting, too.

The software I have let's me specify the diameter of the MPBR in either inches or centimeters. It's how big it is that matters, not what units you measure that size in.

 

[broom_jm]

The software I use is actually called "PointBlank", and it prompts you to specify a sight height when determining a Max PBR.

 

[F2G1D]

The software I use is actually called "PointBlank", and it prompts you to specify a sight height when determining a Max PBR.

That is because the program needs to compute the trajectory with respect to the line of sight.

 

[broom_jm]

That is because the program needs to compute the trajectory with respect to the line of sight.

Ya don't say?

 

[F2G1D]

Ya don't say?

I am a master of the obvious!