Example of sighting in with "Maximum Point Blank"

[possumal]

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I have received lots of questions about sighting in varmint rifles for "Maximum point blank". It is a technique used for years by experienced long range shooters, both on varmints and big game. The idea is to take full advantage of the trajectory of your particular rifle to give you a "Point blank" aiming point out to a certain maximum distance. Here is the info for the Ruger 204 in case any of you fellows are interested. The ranges listed are from 100 yds out to 350 yds on this particular example.

100 yds. ---- 2.45+
150 yds. ---- 3.1+
200 yds. ---- 2.8+
250 yds. ---- 1.25+
275 yds. ---- + (dead on)
300 yds. ---- 1.6-
350 yds. ---- 6 -

As you can see, the highest the bullet is anywhere in this trajectory pattern is 3.1+ at 150 yds, the mid range, with the lowest at 300 yds being 1.6-. Taking into account dead center on a coyote's shoulder or chest at any range from 50 yds to 300 yds, you will hit him with a lethal hit. If a coyote is 100 yds, it is easy enough to hold your horizontal crosshair slightly below dead center but not really necessary to make a lethal shot. The big advantage is that you can still hold dead on at 300 yds without allowing anything for bullet drop. It has to get about 330 yds. or beyond to worry about the drop.

The figures change slightly from calibre to calibre, but can easily be figured with the proper page out of most reloading manuals.

Add a good range finder to your equipment, and you are ready to do some long range business. I find that most beginning coyote hunters make a tactical error sighting in their coyote gun not shooting high enough at 100 yds to take advantage of their trajectory to the fullest as the above

[FinsnFur]

If a coyote is 100 yds, it is easy enough to hold your horizontal crosshair slightly below dead center but not really necessary to make a lethal shot.

You forgot to mention that your example indicates where the shot will approximately hit, and not where the sights should be pointed. Because if you have your rifle zero'd in at 275 yards, and assuming your trajectory listing is accurate, why would you hold slightly lower at 100 yards, when you list as being just just under 2 1/2" high at 100yds.

[possumal]

All I was pointing out is that it is easy to hold slightly low at 100 yds if you have a narrow shooting opportunity like just the yote's head. The idea is to be able to hold dead center on any range up to 300 yds and the actual impact point will always be in the "Sweet circle" killing spot.  If your rifle is sighted in 1 inch high at 100 yds, your maximum point blank will be much less than 300 yds.  My particular point of emphasis is being able to kill coyotes by holding dead center up to 300 yds with a 204.  With my 243, the maximum point blank is about 330 with a similar sight in to the one I posted.  I don't mind it being a little high at 100 through the midrange point, as that is easy to judge if you hunt a lot.  300 yds, on the other hand, is a whole new ball game, and I think it is much easier to be able to hold dead center that to judge how high up on the yotes shoulder to hit him in the vitals.  Even if you have used your range finder at a particular setup, and know that it is 300 yds to the big oak, as an example, it is easier to hold dead on than to judge what is 3 inches above dead on and hold your horizontal crosshair higher to offset a rifle that is shooting 6 inches low at 300. 

[iahntr]

Just curious Al, what'd ya use to come up with that example?
Bullet weight, fps.....
Thanks, Scott

[RShaw]

Actually, a person needs to know three things. Bullet weight, bullet B.C., and bullet velocity.  A chronograph is esential and a good exterior ballsitics program is needed as well.

Randy

[Silencer]

My reloading manuals have all that data in them, of course thats for differnt powder/loads/bullets wts. /etc etc...
Factory ammo will be differ. 

Around the shooting ranges are all 100yds so everyone sights in at that distance.     I've always wondered why when your normal sweet spot is usually alot further and to be dead on at that range would throw the trajectory for a loop.

[possumal]

Fellows, the info is right in your reloading manuals.  That particular chart was made up by Paul Box, chief technician for Sierra Bullets. I did not have the 204 data in my manual as it is too new a calibre, so I requested the info from Paul for the particular load I am going to use on my new T/C 204.  You can bet your farm it is accurate.  I have never caught him wrong on anything about ballistics. To get similar results on my Browning Abolt 243, shooting the 70 grain Blitz King with the load I am using, I have to sight in 2.75 high at 100 yds for a maximum point blank of 330 yds.  This method might not be desirable for people who hunt areas where they seldom get a shot over 100 yds.  If I were hunting that kind of country, I'd want my rifle dead in at 100 yds.  It is all about what you want your rifle to do for the game you are hunting and the kind of country you hunt.  I have killed a bunch of coyotes from 250 yds to 350 yds and I like being able to hold dead on up to 330 yds.  If he shows up at 100 to 150 yds, which is the area where the trajectory has your bullet at its highest point, I can easily hold slightly low as I can judge that factor a lot better than I can a 300 to 350 yd shot. If you forget about the thickness of a coyote's fur on the top of his shoulder and at the bottom of his shoulder, you actually have about a 6 inch circle which represents a dead coyote if you hit him anywhere in that circle.  In my opinion, maximum point blank makes that much easier to do, much less to think about.  You have to give up something on the closer end to get the dead on hold at a further point.

[RShaw]

So...what was your velocity, bc, and bullet weight?  What was your target height used in the calculation?

Randy

[possumal]

Randy, that is not my calculation. It came from Paul Box at Sierra.  It is for a 39 grain Sierra Blitz King out of T/C Encore Pro Hunter 204, with the particular load cranking out about 3600 fps at muzzle.  The ballistic coefficient on that particular projectile is excellent and will hold up very well.  As I said before, the cartridge is not in my Sierra manual as it is too old, so I got the info from Paul.  The testing that Paul and the other technicians do at Sierra is light years ahead of anything I could do anyway.  All I am interested in is the performance.  If the particular load does not suit me, I will get back up with Paul and make a change or two.  The point of the thread is to inform anyone interested of the advantages of using the point blank method of sighting in.

[Rich]

Nprmal "Point Blank" charts were designed for deer sized game..The idea was to allow a hunter to hold dead on a deer at any distance not exceeding 300 yards. With most of the whiz-bang deer rifles of today will do that if you zero in a manner that never allows the bullet to rise more than three inches above line of sight at mid-range, and about three inches below point of aim at 300. Now the vital  chest height of a coyote coyote being less than 1/2  the height of  a deer's chest, a wise hunter will change his sight in technique a bit. With the rather flat shooting coyote rifles of today, I recommend a 100 yard zero of 1-1&1/2" high. This will allow a hunter to hold dead on a coyotes chest out to 250-275 yards.

[coyotehunter_1]

If anyone is interested, here is a link to a good Ballistics program. POINT BLANK, a 100% FREE down load from www.huntingnut.com

http://www.huntingnut.com/index.php?name=News&file=article&sid=3







(Quote from POINT BLANK) "The term "Point Blank Range" means the maximum range you shoot an animal while still holding the rifles sights directly on the center of the vitals. To calculate the user must enter in the diameter of the vitals for the type of animal he intends to shoot. If we assume a vitals area diameter of 6 inches, the calculator will determine a sight in distance where the maximum bullet arc is no higher than 3 inches, and compute the maximum range from this zero where the bullet is still higher than -3 inches."

For an estimation of "Point Blank Range" just click the button  "Calculate PBR", enter the diameter of the kill zone and... 

as an example, we'll use the .223 load above:
For a kill zone of 6.0"
Max. Point Blank Range is 279 yards
Sight in the rifle dead on @ 239 yards


BTW... If you have any questions or problems concerning the Point Blank software, the guy that created PB, DallanC., is also the owner of Hunting Nut. 

[possumal]

Rich's post is dead on about the subject, especially for deer hunters.  If you look at the original chart that Paul Box prepared for me for the .204, the trajectory falls within the parameters of the point blank sighting method.  This particular example puts more emphasis on the long range shot, with the impact point only being 1.6" low at 300. 3.1" high at the midrange of 150 is close enough to the 3" maximum high for me, with the reward being able to hold dead center at 300 instead of 250. A rifle that will perform to those standards is my preference, as I don't hunt deer anymore.  As I have stated before, I don't mind the impact point being 2.45" high at 100 yds and 3.1" high at 150 yds, as I have no trouble knowing those distances just by judgment.  An open shot at 75 to 150 yds on a coyote, standing still, is a simple shot, in my opinion. Most of us need all the help we can get at the longer ranges.  Heck, even marsupial eyes weaken with age!    Finally, a good range finder can be your most useful tool if you faithfully use it on new setups where you are not familiar with the distances to certain landmarks, i.e. the old barn, the big oak, the thick fencerow on the hill.

[RShaw]

Thanks Al. I see what you are saying.

My whole point was this. Whoever is figuring point blank range needs the three numbers I listed above. Also you need to know the velocity and that is only acquired accurately by using a chronograph. Then the numbers are plugged-in to a good exterior balistics program. I do not use the point blank method, but here are the results from the Tac 20. Basically the same thing as a 204. I quit using it for coyotes.

Bullet weight - 35 gr.
Velocity - 4020 fps.
BC -.191

Target Height         Sight-in       High     Low

2 in.                      209            132      237
4 in.                      255            153      292
6 in.                      290            170      333

These figures represent a scope mounted 1.5 inches above the bore.

Target height is critical if you plan on using it for coyotes. From your load data, it appears you have used a target height of 6 inches. Which means the bullet will never be more than 3 in. high or low  between the yardages mentioned.  I did not calculate any yardages for anything above an 8 inch target height as that would be pushing it on a coyote sized animal. Actually the 6 inch my be a little too tall.

Randy