Why MPBR isn’t as good of an idea as it seems...

[Formidilosus]

Zeroing for maximum point blank range is quite often offered as a good way to zero to eliminate “thinking” when an animal steps out. Seems simple enough- zero a rifle at a range that the bullet doesn’t rise above a predetermined height, and when it falls below line of sight at that same distanc; that is your MPBR.

For instance-

300 Win Mag, 190gr Sierra, 2950fps MV.

Set for an 8” target (deer) we have a MPBR of 320’ish yards. Zeroed at 285yds, the bullet will be just under 3” high at 100, hit right at 4” high at 175 or so, dead on at 285, and 4” low at 320.


Sounds good, right? Aim in the middle and don’t worry about range from muzzle to past 300 yards.... Except when actually tested- misses happen. Quite often, actually. Now, there will be a bunch of people saying “works for me” or been doing it for 20 years”, and it does work. Usually. Of course most people tend to forget when they miss as well. But when actually taken to a range with a case of ammo and zeroed exactly as above and shot off a rest at random distances from contact to 320 yards; that setup above will have around a 70-75% hit rate on that 8 inch target. In other words- 25-30% of shots miss, especially between 150-200 yards and again 290’ish to 320 yards. This is reality, it’s been tested a lot.

Why? Well the major cause is group size. The trajectory calculations are for a point. Rifles don’t shoot to a “point”, they shoot in a “cone”. So our 4 inch high or low is to the center of the cone. What about the 50% of shots that are above and below the center of the cone? Combine group size with maximum ordinate (4”) and 4” of drop at 320, and you get quite a few misses.

In fact, between 150-200 yards and 300-320 yards you’ll have a 50% hit rate or less if you hold dead center.


Today we were working with AB Analytics on WEZ (weapon employment zone), I.e.- hit rates given a certain sets of parameters. Not to have a long conversation of how it works, but it “fires” a 1,000 shots randomly with those parameters and plots each one. It very accurately models reality.

A couple of us got to talking about MPBR as well as hunting so we ran the WEZ for it. Given standard conditions, good ammo, 2 MOA precision (which is realistic in the field) and the above combination (300WM, 190gr Sierra, 2,950fps) and an 8” zone-


MPBR results in just over a 70% hit rate.

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You can see in this graph why it’s happening. Right about 150 yards the hit rate starts dropping. The Max Ord and group size is beginning to hurt us.

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Now compare that with aiming dead on at 320 yards with the exact same rifle and conditions-

99.9%

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Should be pointed out that inside of 310 yards it is a 100% hit rate...

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I’ve stated before on the form that MPBR doesn’t work as well as people think, and have gotten into a couple heated discussions about it. Yes, you can kill a deer doing it. Maybe even a few. But if you shoot at enough of them, you will see misses that shouldn’t have happened. This is why.




* A couple of caveats- it’s not exact as the program wasn’t designed for specifically doing MPBR. However it is VERY close, as in- within a few percentage points on the low end. It also matches what I’ve/we’ve seen every time we’ve tested it.

 

[MT_Wyatt]

Very informative - thanks for sharing the results on here. I’ve never tried that method of rifle setup, and looks pretty clear there’s no reason to start.

 

[hodgeman]

Interesting write up...if MPBR is not an optimum way to set up a rifle, what is?

I've used the MPBR method for a number of years- well before laser rangefinders, BDC reticles and dial turrets were common...and never had near a 30% miss rate. Of course, i was pretty picky about shooting the far end of the scale.

 

[Outdoorsman12b]

Form this is good info. My experience with mpbr definitely reflects the model you have posted. Especially at the 150 range. I typically just zero at 200 now.

 

[Laelkhunter]

Excellent explanation !! Thanks for posting.

 

[wannakillabigbull]

I’ve always found MPBR to be an interesting topic from a logic standpoint. I totally agree with setting up a rifle to shoot in such a way that you’re no more than 4” high (in this example at 175 yards), then figure out where you’re ballistics are 4” low (in this example 320 yards). But then the concept of holding dead on throughout this range is what always gets me. If you know you’re in the high 100s then shoot a little low, if you know you’re about 300 then shoot a little high. If you know even roughly what ranges your trajectory is a little high or a little low then, at least for myself, it’s not that difficult to compensate a little so that you’re close to dead on. Even if you’re estimating range and estimating your trajectory it’ll bring your hit rate up significantly. But yet the whole concept of MPBR is to hold dead on throughout the range. Logically that's never made sense to me. Maybe it's a KISS (keep it simple stupid) thing where they don't want to over complicate it.

Good stuff Form.

 

[5MilesBack]

I would think that the option of sighting in at 100 or 200 and having to hold over for everything past that would be even less accurate......correct? Not everybody has dialing scopes to aim dead on at the exact yardage.

The last bull I shot with a rifle was at 25 yards. I had my gun set up for MPBR. You can imagine the thoughts running through my head while he's standing there at 25 yards, and I'm running trajectory charts through my head wondering where to aim. Along with scope height versus barrel at 25 yards etc........the next year and ever since I've had a bow in my hands instead.

 

[wind gypsy]

I would think that the option of sighting in at 100 or 200 and having to hold over for everything past that would be even less accurate......correct? Not everybody has dialing scopes to aim dead on at the exact yardage.

If sighted in at 200 yards your ballistics would never be more than 2" from POA until nearly 250 yards. At 300 you'd be 6 or 7 inches drop. I'd rather hold an estimated 7 inches at 300 and know i'm within 2" up to 240 or so.

If you want to be precise - 100 yard zeros aren't going to be influenced by atmospherics and will give you a good baseline for developing data beyond where MPRB would be.

 

[blutooth]

Great post (although I can’t see the charts for some reason).

I’ve never set a rifle up for MPBR because while I think I’m a good shooter I like to give myself the best chance possible.

If I aim dead center and my rig is set up for that distance I have a +/- 4” tolerance on my abilities (which I know I’ve used depending on my rest, setup, current heart rate etc).

Set up for MPBR, my tolerance changes to something less -0/+4” or reverse at the extremes - which is 1/2 as big as aiming for the distance. So as someone said you need to know your drops and adjust anyway to increase your tolerances.

Why not just zero in at 200 (or 100) yards (which is an easily marked distance at any range and done without any ballistic math) and know your drops anyway. That seems to be the real KISS method. Even if you know nothing about ballistics, cut out the back of your ammo box and tape it to your gun. Even with variations in barrel length, elevation, and temp/humidity you are probably going to have a bigger tolerance window than half of the distances in your MPBR range.

 

[Formidilosus]

Interesting write up...if MPBR is not an optimum way to set up a rifle, what is?

I've used the MPBR method for a number of years- well before laser rangefinders, BDC reticles and dial turrets were common...and never had near a 30% miss rate. Of course, i was pretty picky about shooting the far end of the scale.

Optimum is aiming in the middle, with the middle. We will always shoot better when the bullets fall behind the reticle and that is placed centered on the target. Now, anything past 100 yards is going to require dialing to do that, and it’s not always possible to dial (though it generally is). So the second best option is a consistent linear scale in the same increments as the turret to hold for drop; I.e.- mil reticle/mil turrets. If it’s inside 100 hold dead on. If you think it’s 150-200 hold for 200. If you think it’s past 250 but not farther than 300- hold for 300. Past that, and even inside of that, use a rangefinder. Doing it that way will more often put the center of your group, centered over the target vice MPBR.


With MPBR most of the misses happen in that 50 or so yards of Max Ord, and the last 30-40 yards. It’s easy to test. Zero your rifle for MPBR, set up a target at you Max Ord range and shoot ten shots holding center. Half of your shots will be above the target.

I’ve always found MPBR to be an interesting topic from a logic standpoint. I totally agree with setting up a rifle to shoot in such a way that you’re no more than 4” high (in this example at 175 yards), then figure out where you’re ballistics are 4” low (in this example 320 yards). But then the concept of holding dead on throughout this range is what always gets me. If you know you’re in the high 100s then shoot a little low, if you know you’re about 300 then shoot a little high. If you know even roughly what ranges your trajectory is a little high or a little low then, at least for myself, it’s not that difficult to compensate a little so that you’re close to dead on. Even if you’re estimating range and estimating your trajectory it’ll bring your hit rate up significantly. But yet the whole concept of MPBR is to hold dead on throughout the range. Logically that's never made sense to me. Maybe it's a KISS (keep it simple stupid) thing where they don't want to over complicate it.

Good stuff Form.

The issue with that is it is counterintuitive to aim low and humans have a problem doing it under stress. Quite a bit of research and testing has been done on this- aiming high is natural for distant objects, aiming low for distant objects is unnatural.

I would think that the option of sighting in at 100 or 200 and having to hold over for everything past that would be even less accurate......correct? Not everybody has dialing scopes to aim dead on at the exact yardage.

Nope. See my response to hodgeman.

 

[davsco]

while not easy to find ranges that let you do this, best thing is to actually shoot your rifle at 100, 200, 300, 400, 500 yds and see where it is actually hitting. then you know and aren't guessing. see if your mpbr data works and/or if your theoretical holds work. adjust accordingly. certainly not ethical towards the animal to be taking pot shots, and most of us prob don't want to blow what may be our only chance because our dope was off.

 

[backcountry_hunter]

Form,

While I've never set up a rifle for MPBR I understand the pro/cons and get why people do and why it's not always fool proof.

I would venture to guess most of the set-and-forget guys zero a rifle for 200 vs 100 and have a hybrid of MPBR/holdovers while still holding on vitals out to 400ish with most of the modern calibers. My question is, is there an advantage to setting your scope to 100 and knowing your holdover vs setting it to 200 and knowing the same? It seems like a blend of MPBR and 100 zero.... I have scopes that I spin but have a fair amount of set-and-forget yet with 200 yd zeros. Just honestly wondering what the benefit is between a 100 yd zero and 200 yd zero pending your fluent with holds and know your dope.

thanks in advance

 

[fightthenoise]

What about a hybrid of the two where you do MPBR for a smaller vital area, say 4-5”? Then you can still mindlessly aim dead on out to a set range, your max ord is lower in the middle ranges so you have some buffer built in, and anything beyond your MPBR is still far enough to give you time to range and dial? Seems like this method would take care of most of those misses at max ord.


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[howl]

I used to think that was obvious, but if you talk to many people you find it is not. The other thing is you'll usually run out of MPBR on windage before you get to MPBR on trajectory.

 

[Kraze]

Thanks for the informative post. I used to zero my hunting rifles according to MPBR, but have switched to zeroing dead on at 100. My corrections are easy enough to memorize out to 300, and I can dial them in or hold them in the reticle if I really need to take a quick shot. Anything farther than that and I'll be looking at my drop chart or running the numbers on my phone if there's enough time.

 

[rayporter]

group size can be a killer. as a group shooter I always notice this especially when adverse conditions show up.

 

[JWP58]

For me? Swfa ss + zero 200 + get dope + dial it up = win.

 

[N2TRKYS]

For my application, it works very well for me.

 

[5MilesBack]

At 300 you'd be 6 or 7 inches drop. I'd rather hold an estimated 7 inches at 300 and know i'm within 2" up to 240 or so.

IF you know your exact distance sure you can estimate holdovers and drops. But if you don't know your distance and are shooting for 200 yards at 300, you now have that 6, 7, or 8 inch drop along with any shooting errors.

 

[wind gypsy]

IF you know your exact distance sure you can estimate holdovers and drops. But if you don't know your distance and are shooting for 200 yards at 300, you now have that 6, 7, or 8 inch drop along with any shooting errors.

If you're not going to range and you are that bad at judging distance you shouldn't be taking those shots. If you think it's 300 and it's actually 350, you're off by 6" too.