Maximum point blank range


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drjay9051
November 4, 2011, 12:32 PM
Need some help here. A buddy was talking about MPBR when he goes shooting. As I understand it this is the maximum range at which you need not adjust your elevation to allow for bullet drop. Is this correct. In essence it eliminates hold over out to a given distance depending on the particular round. Am I on the right track??
So the question is why do I see people calculating for bullet drop at even short distances? I have seen guys shoot at say 150 yards and allow for an inch or two of drop. I would think this would be applicable for a .22 long but for a 22-250?



In the military when they use optics such as Eotech is the "dot" an indication of MPBR, in other words just put the dot on center of mass and its good to go be the distance 50 yds or 100 yards?

I'm not clear on the application of MPBR and if it is a good gague why all the fussing with calculating drop etc unless of course I'm a sniper trying to take out a target at 600 yards.

Thanks

J

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hipoint
November 4, 2011, 12:38 PM
sounds like those guys are either excellent shots, or it's overkill... but that's just an opinion from a guy with hi point as a screen name:rolleyes:

Loosedhorse
November 4, 2011, 12:43 PM
So the question is why do I see people calculating for bullet drop at even short distances?The military has a goal of causing a casualty. Almost any centerline hit will do that, as will some limb hits.

A target shooter has a goal of hitting the X-ring. A hunter, of getting a clean, fast kill. These goals demand more accuracy than causing a casualty.

If I'm zeroed at 200 hundred, I know how low I'm hitting at 10 yards, at what range I get to zero before 200, what my max above zero is (and at what range), and how low I hit at 250 and 300.

MachIVshooter
November 4, 2011, 12:51 PM
As I understand it this is the maximum range at which you need not adjust your elevation to allow for bullet drop. Is this correct. In essence it eliminates hold over out to a given distance depending on the particular round. Am I on the right track??

Basically, yes.

MPBR will vary based on the target, especially when hunting. A deer has a smaller vital region than a moose.

If your game animal has an 8" vital zone, you're MPBR is whatever distance that bullet has not dropped more than 4" (assuming it never went more than 4" above POA).

So if your .270 is zeroed at 200 yards, shoots a maximum 2.2" high at 125 and drops 4" below POA at 257 yards, 257 yards is your MPBR, because any further than that, you have to hold high to be inside that 8" circle.

henschman
November 4, 2011, 01:14 PM
MPBR is what I was taught to call "Battle Sight Zero," at least in the context of shooting man-sized targets. Yeah, military rifles usually use a 250 or 300m battle sight zero, which is good enough to get a hit on a man-sized target anywhere from point blank to 350m. Well, a man-sized upper torso is about 20"x20"... and usually all you care about in that situation is getting a hit somewhere on his body. It doesn't matter whether it is an arm, shoulder, or gut shot, or whether it is a "clean kill" double lung or head shot. So with a 250m BSZ on a 7.62 rifle or a 300m BSZ on a 5.56 rifle, the maximum height above POA the bullet reaches is about 12", and by 350m it is about 12" low. Good enough for putting a dude out of a fight, but some applications call for more precision, and you will want to use a BSZ/MPBR that has less deviation from the POA... meaning a shorter range zero, all else being equal. That's why a lot of times you see hunters zeroing for 100 or 200 yards, so within their zero range they are guaranteed a hit within the lung/heart vital area of the target if they do their part.

The whole point of BSZ/MPBR is to allow the shooter to take a shot quickly within a certain range without having to worry about adjusting his sights for elevation. But when you're on the target range and are just punching paper, you usually know the exact distance to your target and have the time to dial in your actual elevation correction for that distance. If you have the time to do it, there is really no reason why you shouldn't use a true zero. BSZ/MPBR is all about sacrificing a little precision to allow for a quick hit when seconds count.

mshootnit
November 4, 2011, 02:08 PM
take whatever the book says your maximum point blank range is, and add 100 yds at least and that is your real-world point blank range.

MachIVshooter
November 4, 2011, 02:27 PM
take whatever the book says your maximum point blank range is, and add 100 yds at least and that is your real-world point blank range.

Upon what facts do you base such ridiculous advise? Your words suggest that you really have no idea what MPBR is and how to calculate it (even though myself and others have clearly explained how to do so)

Dr.Rob
November 4, 2011, 03:31 PM
About 250 yards on my .30-06. At 300 it starts dropping enough to have to think about holding high. Most ballistic charts show the old 1-2" high at 100= dead on at 200, 2" inch low at 250 for many centerfire rifle cartridges. The idea is that to 0-250 yards that means you can hold on a deer's heart and HIT it without making any adjustment to your scope at all.

With my 5.56 MPBR the range at which M193 will reliably fracture from a 16 barrel. More like 150 yards. The cartridge shoots very flat but it loses a lot of punch at range.

drjay9051
November 4, 2011, 03:33 PM
"take whatever the book says your maximum point blank range is, and add 100 yds at least and that is your real-world point blank range."

This is THR forum. Please review it's purpose. Advice like yours I do not appreciate. Unless you are serious which I doubt.

To all others, thank you. So essentially MPBR for a "hit" although maybe not a "clean kill" Yes I see it's purpose in battle. Hoever for hunting which I believe necessitates a clean kill as well as target the MPBR is really not precise enough.

Again, many thanks.

BTW: Anybody know of a reference that contains tables with MPBR for various calibers/loads.

rcmodel
November 4, 2011, 03:40 PM
Download the Free Remington Shoot program.
http://www.remington.com/pages/news-and-resources/downloads/remington-shoot-software.aspx

It gives you the option of letting it figure the optimum PBR sight setting for any common load with several different kill zone sizes.

for hunting which I believe necessitates a clean kill as well as target the MPBR is really not precise enough.Not true.

I have used that sighting-in method for most of my life.
Never oowned a Tackycool scope with tall dials you fiddle & diddle with every shot.
Most game animals will be in the next county while you are still counting "clicks".

It has worked for me on coyotes at 500+ yards, crows at 400+, and deer as far as anyone should be shooting at them from a field position in the first place.

It is as precise & humain as your ability to estime range, remember your trajectory, and hold accordlingly.

rc

robinkevin
November 4, 2011, 03:41 PM
It all depends on where you are sighted in for. I as just a hunter I set my rifles for 100 yards because then I am pretty much dead on the cross hairs up to 50 yards. I then on a rare shot (Longest I have made being 250 yards) I aim a few inches high. Its about knowing you bullet drop. My 30-06 will drop 2.5 inches (if I remember correctly) from 100-200 yards... Bullet drop is pretty easy to guess once you know what the round drops. Cross winds is what I can't wrap my head around... lucky I don't think they come in to play till around the 1000 meter range.

drjay9051
November 4, 2011, 03:59 PM
QUOTE:
Not true.

I have used that sighting-in method for most of my life.
Never oowned a Tackycool scope with tall dials you fiddle & diddle with every shot.
Most game animals will be in the next county while you are still counting "clicks".

It has worked for me on coyotes at 500+ yards, crows at 400+, and deer as far as anyone should be shooting at them from a field position in the first place.

It is as precise & humain as your ability to estime range, remember your trajectory, and hold accordlingly.

rc

I don't follow, RC. Using MPBR for a crow at 400 yards??
I would think the vital organs in a crow are what 4-5 in. diameter. So at 400 yards what in the world kind of rounds has a 3- inch drop. Not looking to flame, just learn. i'm pretty new to this and have not yet looked at ballistic tables. I would think even a very flat trajectory round drops at least 3-4 inches at 400 yards. Am i mistaken?

Haxby
November 4, 2011, 04:12 PM
exteriorballistics.com has information on this. It's Sierra Bullets' site.

rcmodel
November 4, 2011, 04:16 PM
I don't follow, RC. Using MPBR for a crow at 400 yards??

What I meant was, I sight in my rifles for MPBR, then shoot at all ranges to figure the exact drop in 100 yard increments.

I know the rifle is shooting to MPBR zero at 250 yards.
I know the bullet will never be more or less then 3" off the line of sight to 300.
I know it drops a set amount at longer ranges then that.

As an example:
The trajectory chart taped to the ammo box reminds me my 22-250, 55 grain load:
100 = +1.75".
200 = +1.67".
250 = 0.
300 = -2.9".
400 = -13.6".
500 = -32.7.

For a standing crow size target in calm wind, a center hold will hit it from 0 to 300 yards.
Holding one crow high will hit it at 400.
Holding 3 crows high at 500 will hit it.

And I never counted a scope click or touched a dial.

It is also closer them most anyone can estimate long ranges without using a range finder unless they shoot long range all the time.

Years ago when I hunted varmints almost daily on the Kansas plains, and shot for 5th Army AMU?
I could hit it as far as I could see it.
Not so much anymore that I am 67 years old though!

rc

MachIVshooter
November 4, 2011, 05:31 PM
Hoever for hunting which I believe necessitates a clean kill as well as target the MPBR is really not precise enough.

It is so long as you're accounting for vtial zone size. Like I said, if you have an 8" vital zone, that's a 4" radius, so any bullet that will not go above or below POA by more than 4" inside of a given range means that you don't need to hold over (or under) inside that MPBR distance for a clean kill.

No, we can't use battlesight zero and MPBR numbers for hunting for the reasons mentioned above; We're looking for a clean kill, not a casualty, so our MPBR as hunters is only the vital zone, not entire 15"x20" torso + abdomen.

drjay9051
November 4, 2011, 05:37 PM
RC:

Got it. So you estimate ranges without finder? I suppose practice is key. I like the MPBR idea. I have buddies who do not shoot bullseye just fun and they get crazy with their estimates, holdovers, bullet drifts etc. One guy has a wind meter I think it is called a kestral to calculate drift.

Funny thing is he is a very good shot!!

I think they like to play sniper on the weekends.

J

rcmodel
November 4, 2011, 05:54 PM
Yea I know people like that too.

But like I said before, if you hunt medium size varments, the game will be in the next county while you are fiddling around with all those gadgets & making scope adjustments getting ready for the shot.

Sighting in MPBR, knowing the trajectory, and hold-over is the fastest way there is to get off an accurate long range shot on coyotes, crows, etc.

rc

JimKirk
November 4, 2011, 08:30 PM
Folks tend to forget that MPBR has a "target" size ... it can be any "size" you want/need. The so called average whitetail is said to have a 16" kill zone up/down... so you would think an 16" MPBR would work ... but you have to factor in the average "shooter" (SF)... so maybe a 8" target size would be better... that way the SF+ MPBR would get most folks into the 16" kill zone. That means the bullet would be no higher or lower than 4" above or below the line of sight...

Base the MPBR target size on your game size and shooting abilities...

Here is a link that "if" you input all the required accurate data ... it will be pretty darn close to real world findings(speaking from my experiance)...

http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

Jimmy K

jmr40
November 4, 2011, 08:50 PM
If I hunted where 300+ yard shots were the norm I MIGHT consider using this method. I've tried it and didn't care for it. For me it is much simpler to just zero at 100 yards and know where I'm hitting at longer ranges. I don't think it really helps much. With all of my rifles I'm around 3" low at 200, and around 12" low at 300. (I'd still be 7" low at 300 with a 200 yard zero). I can hold on hair all the way out to 300 yards with either method.

Beyond 300 yards most folks are better off with a range finder and a scope with long range dots. Don't care for turning dials either, but the dots are fast and work well.

MachIVshooter
November 4, 2011, 09:10 PM
Beyond 300 yards most folks are better off with a range finder and a scope with long range dots.

Range finders are important, period.

You have no scale with objects of known size from which to make range estimations as you would in a settled area, so it's very easy to make egregious miscalculations. The first year I had my rangefinder out with me, I discovered just how far off one's guestimation can be; We were all looking at a rock and trying to guess. Of the four of us, I was closest, and was still off by 160 yards. I had said 350, the rangefinder said 513. My .25-06 is zeroed at 200 yards. With 117 gr. BT bullets with a B.C. of .438 leaving the muzzle at 3,195 FPS, my MPBR is 280 yards for an 8" kill zone, so I'd have held just a little high for 350; If it had been an animal, I'd have missed completely by well over a foot at 513 yards. And that's with a very flat shooting cartridge. Imagine with a .308.....

rcmodel
November 4, 2011, 09:33 PM
I guess I had a leg up judging distance most of the time growing up here in Kansas cattle & farm country.

Sections of land (mile sq / 640 acre / 1760 yards sq) are generally divided into 1/4's, or 160 acres.
With gravel or dirt roads crossing every mile.

Farm fields and range land are often divided further into 80 acre fields.
So each 1/4 section line fence is 880 yards.
Each 80 acre line fence is 440 yards.

So if a coyote runs to the next line fence from where you are and stops to look back?
You get to know very well how big they look at various distances while going about your normal business farming and chasing cows around trying to get them to do your bidding.

It's then pretty easy to estimate the range close enough for Goober-Mint work with a 22-250 or .220 Swift!!

Not so easy in the mountains or desert with no known distance landmarks.

rc

Omnivore
November 4, 2011, 11:17 PM
Should start with the basic-- The clinical definition of PBR is; that range at which the bullet has dropped below the line of sight by the same amount that it rose above the line of sight. That will change by caliber, load, sight height over the bore, and it'll change a lot with zero. The Point Blank Target Size (the rise above LOS x 2) will also naturally also change with those variables.

I see it's unsefullness mostly as a means of selecting a caliber or load for precision, long-range shooting. Otherwise, practice works better than crunching numbers, but it is good to look at the numbers just to help understand what's happening when you change some part of the setup, i.e. use this zero or that zero.

"Maximum" PBR has no meaning for me. Shooting and seeing where the bullets hit does.

2zulu1
November 4, 2011, 11:34 PM
Basically, yes.

MPBR will vary based on the target, especially when hunting. A deer has a smaller vital region than a moose.

If your game animal has an 8" vital zone, you're MPBR is whatever distance that bullet has not dropped more than 4" (assuming it never went more than 4" above POA).

So if your .270 is zeroed at 200 yards, shoots a maximum 2.2" high at 125 and drops 4" below POA at 257 yards, 257 yards is your MPBR, because any further than that, you have to hold high to be inside that 8" circle.
+1

This time of year I carry a M29 Mountain at my place. 200gr XTPs/1500fps have a PBR of 140yds with a 113yd zero/6" target.

That means, with sights adjusted for a 113 yard zero, the bullet will stay within 3" hi/low out to 140 yards.

waidmann
November 4, 2011, 11:48 PM
drjay, I suggest battlesight zero, maximum point blank range etc. are confusing the issue. Take the givens, the gun, optics, loaded cartridge and an acceptable impact area. The target whether it is one, two or six inch diameter is based on all the variables you decide just as you decided all the other givens.

Now imagine that diameter is that of a length of pipe. Your line-of-sight is down the center of the pipe. Your desire is for the bullet to fly the maximum distance in the pipe without leaving it. The trajectory of the bullet will cross the line-of-sight in two places one rather close (25 yds ?) the other at extreme range. The bullet will after having achieved its second "zero" fall fairly quickly through the bottom of the imaginary pipe.

You can get some fair ideas from the commercial ballistic charts. You will know it by firing at multiple ranges to confirm what is truly happening. Your level of skill is a very real part of this mix.

I completely associate myself with all the comments regarding the desire to humanely harvest game. In my area 100 yds is a long shot. I haven't felt the need wring 300+ yds out of a rifle in many years.

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