specweldtom
Well-Known Member
What is the standard (or most widely used) window size for determining maximum point blank range? I would like to know if I'm doing it right.
Thanks, Tom
Thanks, Tom
Max point blank range
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ss7mm
Well-Known Member
That would depend on what you're shooting and what you'll accept as the maximum allowable distance for a hit above and below your point of aim. Theoretically an elk would allow you to have a much greater point blank range than a rabbit.
If you've determined that you will accept a hit anywhere in a 10" circle then you will accept a hit from 5" above to 5" below your point of aim and that would let you figure "your" acceptable point blank range. Do your ballistics figures and see at what ranges you will never be more than 5" above, or below your point of aim, and that will give you your maximum point blank range.
This is one of the reasons I sight all of my big game rifles in to be zeroed at 300 yards instead of 100 yards. If I'm presented with a quick shot out to may maximum point blank range then I can take that shot without sight adjustments and know where it will hit.
My thoughts are that even though some people may say that an animal may have a "kill zone" of a certain size, I never use that in figuring my pbr. I've heard people say that an elk has a kill zone of anywhere from 18-24" and I would never use those numbers for my pbr.
On my 7mm AM I figure my pbr on a 6" (+- 3") circle for big game. That gets me out to almost 500 yards. However, given the time to do so, I'd still dial for anything if I could. I've killed 4 big game animals so far with my 7mm AM and all have been dialed, even though I could have used my pbr on one.
If you've determined that you will accept a hit anywhere in a 10" circle then you will accept a hit from 5" above to 5" below your point of aim and that would let you figure "your" acceptable point blank range. Do your ballistics figures and see at what ranges you will never be more than 5" above, or below your point of aim, and that will give you your maximum point blank range.
This is one of the reasons I sight all of my big game rifles in to be zeroed at 300 yards instead of 100 yards. If I'm presented with a quick shot out to may maximum point blank range then I can take that shot without sight adjustments and know where it will hit.
My thoughts are that even though some people may say that an animal may have a "kill zone" of a certain size, I never use that in figuring my pbr. I've heard people say that an elk has a kill zone of anywhere from 18-24" and I would never use those numbers for my pbr.
On my 7mm AM I figure my pbr on a 6" (+- 3") circle for big game. That gets me out to almost 500 yards. However, given the time to do so, I'd still dial for anything if I could. I've killed 4 big game animals so far with my 7mm AM and all have been dialed, even though I could have used my pbr on one.
specweldtom
Well-Known Member
ss; thanks, makes more sense than just picking a number. My go-to hunting rifle is a .30 x .378. I need to get in some range time and verify the external ballistics of my pet load, a 190 gr smkhp, then decide on what size window I'm comfortable with.
Thanks again, Tom
Thanks again, Tom
crowsniper
Well-Known Member
have you tried these websites External Ballistics Calculator JBM - Calculations - Trajectory (Basic)
ss7mm,
I like the way you do that, it surely works.
Mine is very similar. I zero at 100, verify impact point at different ranges, the PBR for my 300 RUM 210 Bergers', the distance is 265 yards zero, for a 6 inch diameter which is good to 315 yards. So from 0 to 315 I don't have to worry, here's the difference, though I was originally zeroed for 100 yards, my turret is set for 2.1 MOA which is zero at 265, and I hunt like that. If I have to shoot at 500 yards, with a 100 yards zero I need 5.0 MOA; but since the turret is already at 2.1 (very visible) I just continue to 5.0. Man I hope I made any sense of that! Sure is nice having them flat shooting Allen Mags.
I like the way you do that, it surely works.
Mine is very similar. I zero at 100, verify impact point at different ranges, the PBR for my 300 RUM 210 Bergers', the distance is 265 yards zero, for a 6 inch diameter which is good to 315 yards. So from 0 to 315 I don't have to worry, here's the difference, though I was originally zeroed for 100 yards, my turret is set for 2.1 MOA which is zero at 265, and I hunt like that. If I have to shoot at 500 yards, with a 100 yards zero I need 5.0 MOA; but since the turret is already at 2.1 (very visible) I just continue to 5.0. Man I hope I made any sense of that!
Sure is nice having them flat shooting Allen Mags.silvertip-co
Well-Known Member
PBR is junk science(junk balllistics) created by gun magazine guys. It means nothing. Point blank is 1" from the end of your barrel. I've read hundreds of articles about PBR and it's all marketing crapola. Just go by any good ballistics chart or make your own.
ss7mm
Well-Known Member
"au contraire mon ami". Created by gun magazine guys.......quite possible. I have no idea who first coined the phrase.
It means nothing..........Actually, because it is a phrase used by many, that has a definition related to shooting, it does mean something. See usually accepted definitions above. Unfortunately your definition is different from almost everyone else's definition.
it's all marketing crapola.......most advertising and marketing stuff is a form of crapola but, in all reality, to the majority of shooters in the good ol USA it does mean something. And by "the majority of shooters in the good ol USA" I mean those that might shoot half a box of shells a year and have no idea what a turret is nor do they even know that downrange ballistics even exist.
For the average, shoot it once and then go hunting in the fall person, if they understand the concept and where the bullet strikes in the dreaded PBR then they at least have one small bit of information they might not have otherwise.
Is it the best way to hunt.....nope, never said it was. Does it have any usefullness in the hunting field.......sure does if used properly.
Do I use it.......read the above post and you'll see that I dial for everything I possibly can. But, if presented with an ethical shot under conditions that will allow me to take the shot, then I will use the data and info contained within the confines of the PBR and make that shot.
Just go by any good ballistics chart or make your own......I have more charts, drop sheets, field test data and Palm help than I can pack at one time. But, whether you coined the phrase or some dim-witted writer of some $.25 gun rag did, it's out there so I say if somebody has a question about it then I'm gonna give them as much info as possible so they might understand what happens when they pull the trigger. If I just told them it's crap then how did I help them? And yes, if they ask about PBR I'd also bring up the basics of long range stuff and provide any help I could.
Why do you think 'ol Jack O'Connor sighted his venerable 270 in a little high at 100 yards? Regardless of what he called it, he was taking advantage of what is known today as the PBR of his gun and load. He didn't dial for anything but he knew where the bullet hit. Again, it hit somewhere in the worthless PBR.
specweldtom
Well-Known Member
Boys. it's only a month until rifle season opens, and I'm confused. Does the term "point blank" really mean the same as "maximum point blank range"? And who originated the term "point blank" anyhow (was it the military?) and does it really mean 1" from the muzzle? Am I going to have to get 1" from my game to shoot 'em at maximum point blank range? Hell, I might as well just bayonet 'em. Is that illegal? Maybe there's a license. Man, huntin' gets harder and harder!
Help me, Help me, I've fallen and cain't get up! Tom
Help me, Help me, I've fallen and cain't get up! Tom
Yes, "point blank" and "point blank range" or "maximum point blank range" or "PBR" or "MPBR" it all reffers to the same thing.
Here's a quote from ballistics Explorer:
The easiest way for me to explain it is like this:
Let's say you have a 6" paper plate that you want to able to hit every time by aiming dead center regardless of the distance; so you ask me, at what distance should I zero my rifle to do this and what would be the Maximum distance that I can place the 6" paper plate to still be able to hit it?
I would get all the info about your weapon, the conditions etc. plug it into one of my programs and tell it that the vital Zone (VZ) is 6" inches. Then the program tells me where I need to zero Example 260 yards and where would be my maximum distance. Example 315 yards. So anything from the muzzle all the way to 315 yards, all you have to do is aim dead center of the target without making any corrections and if you do your job you will hit the paper plate some where inside the vitals.
From the muzzle to 315 yards, the bullet will not go higher then 3 inches, nor it will go lower than 3 inches.
MPBR - Exists
All I can say about this is I have owned my 7MMRM for 18 plus years and I have proven this through actual shooting that it does work. I'm zeroed out bullseye shot @ 336 yards and MPBR is 370 yards with a 12 " hold over and adjusting properly for the wind I will hit @436 yards and with 30" hold over and adjusting properly for the wind I can hit @550 yards. All I can say about this is I have done it. PERIOD talking and reading is one thing - GO OUT AND PROVE IT. I HAVE. (This is with Roll your own rounds)
One month is probably not long enough to insure a good MPBR with a hunting season just coming up.
It takes time, practice and shooting.
I would insure that you can hit effectively @100 and 200 yards for this years hunting season.
All I can say about this is I have owned my 7MMRM for 18 plus years and I have proven this through actual shooting that it does work. I'm zeroed out bullseye shot @ 336 yards and MPBR is 370 yards with a 12 " hold over and adjusting properly for the wind I will hit @436 yards and with 30" hold over and adjusting properly for the wind I can hit @550 yards. All I can say about this is I have done it. PERIOD talking and reading is one thing - GO OUT AND PROVE IT. I HAVE. (This is with Roll your own rounds)
One month is probably not long enough to insure a good MPBR with a hunting season just coming up.
It takes time, practice and shooting.
I would insure that you can hit effectively @100 and 200 yards for this years hunting season.
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specweldtom
Well-Known Member
Not to worry. My last post was pretty lame humor. I was jist funnin' ya'll.
I don't really give a crap who came up with either phrase, I've been using mpbr for years, just asked if there was a widely accepted window size for determining it. I was using 4"--2 up and 2 down. That works with a 200yd zero, but does limit mpbr even with a 30 x 378. On the plus side, that small of a window shortens mpbr enough to pretty much take wind drift out of consideration, particularly with the 30 by. ss7 made a lot of sense. Mpbr should be determined more by the size of the vital area of game than an arbitrary number, but as you allow a bigger window, mpbr shots get longer and you have to start doping wind. He also said that if you have time, to heck with mpbr, dial the shot in.
I got some good answers to a reasonable question.
on edit: The doctors say that I'm much better now, and soon will be able to eat oatmeal all by myself.
Thanks to all. Tom
I don't really give a crap who came up with either phrase, I've been using mpbr for years, just asked if there was a widely accepted window size for determining it. I was using 4"--2 up and 2 down. That works with a 200yd zero, but does limit mpbr even with a 30 x 378. On the plus side, that small of a window shortens mpbr enough to pretty much take wind drift out of consideration, particularly with the 30 by. ss7 made a lot of sense. Mpbr should be determined more by the size of the vital area of game than an arbitrary number, but as you allow a bigger window, mpbr shots get longer and you have to start doping wind. He also said that if you have time, to heck with mpbr, dial the shot in.
I got some good answers to a reasonable question.
on edit: The doctors say that I'm much better now, and soon will be able to eat oatmeal all by myself.
Thanks to all. Tom
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That's the reason some good willed people that want to help others stop doing it because of ill lame humor like that; you never know when will be the next time someone else tries to make an idiot out of you and you don't help someone that really needs the help thinking that it's again some garbage like that!
urbaneruralite
Active Member
- Joined
- Nov 20, 2005
- Messages
- 43
The one factor that seems to be absent from discussions on mpbr is that most folks miss every time they shoot an animal. By missing I mean that you don't hit your exact point of aim on an animal. Often, the cross hair isn't even exactly on the poa when the trigger breaks.
If a hunter ,certainly not one on lrh, but a hunter, uses a calculated MPBR of 4" radius and can only hold within an inch of an intended POA, then the actual radius is 5" and the calculations are invalid. The same goes for the size of rifle groups. If a rifle shoots 2 MOA, then an MOA must be added to the MPBR radius.
The MPBR calculated radius should be smaller that the vital size of an animal. When hunting in cover, it should be smaller than the likely size holes in cover that you may shoot through.
If a hunter ,certainly not one on lrh, but a hunter, uses a calculated MPBR of 4" radius and can only hold within an inch of an intended POA, then the actual radius is 5" and the calculations are invalid. The same goes for the size of rifle groups. If a rifle shoots 2 MOA, then an MOA must be added to the MPBR radius.
The MPBR calculated radius should be smaller that the vital size of an animal. When hunting in cover, it should be smaller than the likely size holes in cover that you may shoot through.
