I looked at both programs huntingnut and sst benchrest and the data on point blank range is different. Point blank 6" is the same as sst's 4". Why is that?

Marius

PBR, by definition, is the range at which you will sight-in a firearm so that the bullet's trajectory goes no higher nor lower than a specified distance.

Change any variable and the PBR changes.

Yes I understand that but have a look at the two. The info will look the same as this example.


Kill zone Zero distance Max dist
6" 290 yards 340 yards Point blank
4" 284 yards 329 yards sst

Marius,
you have just stumbled on the basics of the "what's the point" part of shooting... do a MPB on the 308 and 300 weatherby with 165 gr bullets.. load the 308 at 2600 and the 300 at 3200.... and use a 6"mpb (which is 6 UP and 6 DOWN)... and be floored at the little USEFUL difference, to the average hunter...

average hunter being defined as someone who thinks a long shot is 250 yards (is to me for a hunting rig)

jeffe

Ah yes Jeff, perhaps you have lighted a small candle in the vast darkness of velocity hype and trajectory bullshit.

PBR for +/- 2.5 inches for my most commonly used rifles:



.220 Swift, 50 grain Sierra Spitzer, 3906 FPS

Max Range 320, 100 yard sight-in 1.81, Point Blank Zero 280



.22-250, 52 grain Sierra HPBT, 3207 FPS

Max Range 310, 100 yard sight-in 1.91, Point Blank Zero 270



.22-250, 55 grain Sierra Spitzer Boat Tail, 3410 FPS

Max Range 290, 100 yard sight-in 1.94, Point Blank Zero 250



.243 Winchester, 87 grain Sierra HPBT, 3010 FPS

Max Range 260, 100 yard sight-in 2.18, Point Blank Zero 220



6mm Remington, 87 grain Sierra HPBT, 3128 FPS

Max Range 270, 100 yard sight-in 2.13, Point Blank Zero 230



.25-06 Remington, 120 grain Nosler Spitzer Boat Tail, 3076 FPS

Max Range 280, 100 yard sight-in 2.06, Point Blank Zero 240



.25-06 Remington, 120 grain Sierra HPBT, 2922 FPS

Max Range 260, 100 yard sight-in 2.26, Point Blank Zero 220



.25-06 Remington, 120 grain Nosler Spitzer Boat Tail, 2922 FPS

Max Range 280, 100 yard sight-in 2.06, Point Blank Zero 240



.264 Winchester Magnum, 140 grain Sierra HPBT, 3132 FPS

Max Range 280, 100 yard sight-in 1.94, Point Blank Zero 240



.270 Winchester, 140 grain Sierra HPBT, 2944 FPS

Max Range 260, 100 yard sight-in 2.04, Point Blank Zero 220



7mm Remington Magnum, 168 grain Sierra HPBT, 2943 FPS

Max Range 270, 100 yard sight-in 2.00, Point Blank Zero 230



7mm Remington Magnum, 175 grain Nosler Partition, 2903 FPS

Max Range 260, 100 yard sight-in 2.09, Point Blank Zero 220



.30 Carbine, 110 Grain Sierra Round Nose, 2136 FPS

Max Range 170, 100 yard sight-in 2.19, Point Blank Zero 150



.30-06 Remington, 168 grain Sierra HPBT, 2801 FPS

Max Range 250, 100 yard sight-in 2.18, Point Blank Zero 220



.30-06 Remington, 180 grain Sierra HPBT, 2705 FPS

Max Range 250, 100 yard sight-in 2.23, Point Blank Zero 210



.300 Winchester Magnum, 200 grain Sierra HPBT, 2986 FPS

Max Range 270, 100 yard sight-in 1.99, Point Blank Zero 230



8mm Remington Magnum, 220 grain Sierra Spitzer Boat Tail, 2823 FPS

Max Range 260, 100 yard sight-in 2.10, Point Blank Zero 220



.375 H&H Magnum, 300 Grain Sierra Spitzer Boat Tail, 2596 FPS

Max Range 240, 100 yard sight-in 2.27, Point Blank Zero 200



.44 Remington Magnum, 240 grain Sierra JHC, 1919 FPS

Max Range 160, 100 yard sight-in 2.28, Point Blank Zero 140



.45-70, 300 Grain Sierra Flat Nose Hollow Point, 2161 FPS

Max Range 160, 100 yard sight-in 1.98, Point Blank Zero 140



.45-70, 350 Grain Hornady Round Nose, 1924 FPS

Max Range 160, 100 yard sight-in 2.24, Point Blank Zero 140



.45-70, 400 Grain Speer Flat Nose, 1788 FPS

Max Range 150, 100 yard sight-in 1.80, Point Blank Zero 130



.45-70, 500 Grain Hornady Round Nose, 1657 FPS

Max Range 150, 100 yard sight-in 1.98, Point Blank Zero 130



.458 Winchester Magnum, 500 Grain Hornady Round Nose, 2173 FPS

Max Range 190, 100 yard sight-in 2.19, Point Blank Zero 160

Marius,



I know it doesn't answer the question but here is my personal observations on PBR.



1) A lot of people fudge by using the center of groups as the reference points when setting the PBR limits.

In reality, as Steve implied, the highest shot in the group at the near range has to be at or under the elevation limit while at the far elevation limit the LOWEST shot in the group has to be at or above that elevation limit.



2) In the field most scoped high-power rifles zeroed at 100yds will have a 6" PBR out to 220yds or so. This will allow "surgical" precision at close ranges without worrying about hold-under. This is especially valuable here in wooded and broken terrain when a shot may be confined to the neck because of foliage.



So I'm not a huge fan of PBR as range estimation without a range finder starts getting pretty dicey out at the ranges where PBR should be the greatest help but isn't because cartridges simply don't shoot flat enough. (Of course with a range-finder a memorized drop chart is all you need) To make it of even less value for me I am very conservative with my kill zone size- 6" for deer and 8" for elk.

Steve,

when you say very conservative, I bet you MEAN a 3" pbr (3 up and 3 down) on deer, which gives a 6" range... at elast quicktarget's calc for mpb is up/down(radis) not diameter

j

Yes I mean kill zone diameter. I use Pointblank and Ballistix for Windows.



I don't mean to imply PBR is not worth sighting-in for. I'm sure if I lived in more open country I might have more use for it.



It's just that out there past 300 yds any bullet drops through an 8 or 10" zone pretty fast yardage-wise, leaving little room for error in range estimation, which is by definition what it is supposed to alleviate.



Stubblejumper,



True. It would be interesting to see before and after shots of a shaved mountain goat but nobody seems to wants their taxidermist to shave their $5000 trophy.

Thanx,

I take my range findings and compare it to the ballistics, and also use my own findings on the range memorize it for hunting. It was just an interisting thing I saw and thank you for some light as I am a new comer to ballistic programs.

Marius

Jeff,

I believe you "mis-spoke" yourself when you wrote, '6"mpb range(+/- 6")' 6" mpb range would be +/- 3".


Everyone else,

The purpose of this manner of zeroing a rifle is to negate the need for range finding. If you are zeroed for 220 to 240, depending upon you caliber and bullet weight, you are inside the six inches circle from muzzle to about 260-280 yds. You hold on the animal's vital area (heart-lung zone) and pull.

When you look at the the cold hard facts, as Steve indicates, there isn't a lot of difference between most high powered rifles. With better powders and better bullets, the differences really become miniscule. You can drop back one bullet weight in a caliber, and drop from a magnum to a standard caliber. There is no practical difference between a hit in the zone with a 165 grain Nosler Partition vs. a 180gr Partition in most animals. One can really say today, in most circumstances, pick the rifle you can hit with reliably. Ku-dude

KD,



I could be wrong, and don't mind if I am. It's been my understanding that the inches in max point blank means the allowable travel ABOVE and BELOW LOS. So a 6" PBR/or MPB means it's allowed to travel 6 above and 6 below



here's what I said "I bet you MEAN a 3" pbr (3 up and 3 down) on deer, which gives a 6" range" which is how I understand max point blank range, that it's the RADIUS of a circle (due to grouping), or the +/- of elevation.



alot like the equations

c=pi*diameter

or

c=2pi*radius





jeffe

Jeff,

I went back and read my old Sierra manual where I was first exposed to the concept of MPB range. To tell you the truth, I think we are both wrong, or both right.

MPB Range is the distance at which a particular bullet and load will travel a linear distance without going above or below a stated number of inches. According my old manual, they used the term "vital area" to define the size of the entire circle, and spoke in terms of the bullet being the radius of that vital area above or below the line of sight.

Sierra used 10" vital area for big game hunting bullets, 12" for iron target shooting, and 5" for varmints. I use a six inch circle as standard because our native deer are so darn small and many of the antelopes I hunt in Africa are even smaller. If you are an elk hunter, I can see how a 12" vital area and +/-6" would be a workable vital area and allowable rise and fall respectively.

Seems as if we want to be clear, we'd have to state both the size of the vital zone and the +/- number we used to compute our maximum range figure. Just about the time I think that I've learned something, I find I did not know quite as much as I thought I did.

Although I "knew" it, it was rewarding to be reminded in siting in for MPB range, I must use the center of mass of my group as my aiming criteria such that the widest possible dispersion of my shots will still be inside my defined vital area. If my rifle is shooting a half inch group at 100yds, my max elevation at 100 yds 2.75" to stay within my 6" circle.

Good shooting. Ku-dude

KD,
I think you are right.. we are both both... we'll just say it as diameter and then add max rise/fall.. good idea.

or, you can go by the jeffe rule of rule...

2600+fps, 1" high at 100,means ~ 1" low at 200, 8 inchs low at 300

2400-fps 2' high at 100, 4" low at 200, don't shot 300.

Since i nearly never shoot past 150, 1"high at 100 with scoped rifles, and 1" high at 50 with iron sights means I can alway aim "at hair, not air" for the distances I am comfortable with...

as for small deer... i've seen labs FAR larger in weight than east texas deer

jeffe