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FINALLY

I finally got the rifle dialed in yesterday at the range. 3" high at 100 yrds. It still needs tweeked a little, but it's good enough for now.

So how do I figure out where to zero it at? I'm thinkin at setting it at 250 yrds.
What variables do I need to keep in mind? Im not reloading yet so I have to use factory ammo (I spent over $90 yesterday shooting= 26 rounds). YIKES!!!

I get custom dials from Leupold, so can I just pick a bullet weight and go from there.

Where can I get similar data that coincides with my specific rifle?

Oh. I was shooting 250 gr. Federal ammo.

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Or!

Or even another thread someone has.

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There are a few thing that

There are a few thing that you are going to have to find out to be able to figure out the ballistics of a bullet. One is the ballistic coefficient of the bullet that you are shooting. That along with the velocity of the bullet as it leaves the barrel of your rifle. If you find published data for the velocity of the round that you are shooting you can usually subtract a hundred feet per second from it to find out what it actually is doing. But different rifles will have slight variations of velocity shooting the same round. Different bullets are going to have different ballistic coefficients and leave the barrel at different speeds so you would need a set up for each and every round that you are shooting.

I personally do not mess around with turret knobs to change the point of impact for different distances on my hunting rifles. I zero them in for dead on at 200 yards and that usually puts them good out to 400 yards and then you need to start elevating the barrel and for 99% of any and all hunting situations 400 yards is a real long shot but not uncommon.

You have to figure that if you are going to adjust a knob to get to your point of aim you are going to have to have a range finder and range the animal, then you need to play around with the knob to get it set to where the range is. All the while that you are doing this the animal is usually moving while it is feeding, so in the time that it takes for you to get a reading and adjust the sight picture the animal has walked behind a tree or rock to be gone for ever.

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I use the MPBR methiod of

I use the MPBR methiod of zero at an 6" target. It keeps the bullet no more than 3" high or low out to MPBR. It's useable out to 300yds with every rifle I have. If you don't know the velocity and get what the manufacturer claims and don't have the BC of the bullet, it's still possible to sight in at MPBR and 200yds. Get the advertised range and the bullet weight. I can use the weight of the bullet from another similar bullet to come up with a BC and I'll just use the advertised velocity. Feed that through my cronograph's ballistic program ant it will get you close. Next thing would be for you to sight in which ever way you want and then fire at indicated ranges. By doing that and adjusting, you won't know the exact velocity or BC but it won't matter as you'll have shot the load to see where it hit's at different ranges. It will be as close as you can get without real velocity and BC and more than adequate.

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So the BC of a bullet listed

So the BC of a bullet listed by the manufacturer doesn't change from one load to the next....but the velocity can vary depending on what the bullet is shot from? Example: case load, length of barrel, current temp. and so on. Does that make sense?

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Of course it does

PapaSzakal wrote:
So the BC of a bullet listed by the manufacturer doesn't change from one load to the next....but the velocity can vary depending on what the bullet is shot from? Example: case load, length of barrel, current temp. and so on. Does that make sense?

 

Of course it does. Thung is fairly large change's in BC don't amount to a whole lot in trajectory. I discovered that some years back when I compared the trajectory of two different bullets of the same weight but different BC's. I was stunned that the higher BC bullet didn't fly a whole lot flatter, but they don't. All nyou really need to do is establist a trajectory at the zero point and then shoot against the data provided. You'll find there is not a lot of difference between same style and weight bullet's. I haven't looked it up but I'd bet that there isn't a fast cartridge made that can zero at 200yds and not need some hold over at 400yds that is suitable for big game.

And the 500yd+ shot's we always hear about are not all that common inthe first place. Generally if you get a shot that far away, you are looking for it, and, guy's do look for it and much farther. But the bullet that may work in one form or another may well blow up at much more normal ranges. So if you want a bullet that will act better at 500yds+ you'd probably be better off to pass on the 100-150yd shots!

To get what is considered flat at even 400yds, will require at least some hold over. The scopes with mil dots in them. You need to use a bullet that will come very close to what the dot's are tuned for. But very close is subjective. You drop down to use the longer range dot and your really raising the path of the bullet. There is no such thing as flat, it's simply a term used to describe the path of a bullet from one style to another.

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The BC's of different

The BC's of different manufacture bullets are not always the same. Here are some from the reloading manuals that I have for a 250 grain flat base spitzer bullet:

Barnes .521

Nosler Partition .473

Hornady .431

Speer .458 So as you can see they are quite different.

What I would do if I was you is to actually zero my rifle at 200 yards. Not 2 or 3 inches high at 100 but actual shoot a target at 200 yards. Then extend the range to 300 yards and fire 3 shots and record the bullet drop, then to 400 yards and do the same and then if possible extend the range to 500 or 600 yards and record the information. This way you will know what the drop actually is along with finding out how hard it is to shoot a good group at those ranges.

If you can't get those ranges I am going to take some guesses at what is going on. I am going to presume that you are shooting Federal .338 Win. Mag with a 250 grain Nosler Partition with a published velosity of 2660 fps. So to make things easier for me I'll raise the velosity to 2700 fps. With a 200 yard zero you should be 2" high at 100 yards,8.5" low at 300 yards, 24.5" low at 400 yards, and 48.8" low at 500 yards.

Now if your velosity is down to 2600 fps and a 200 yard zero here is what the bullet will do. 9.2" low at 300 yards, 26.3" low at 400 yards, and 53.3" low at 500 yards.

For a reference I got the bullet velosity from the Federal Premium Ammunition web site. http://www.federalpremium.com/products/rifle.aspx

and the bullet performance from my Nosler #3 Reloading Manual

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Ok

Thanks Don for the input.

Critter. I live in southwest Ohio. The closet long distance range is about 3 hours in any direction. There's a place called Thunder Valley southeast of Columbus, OH. i've been wanting to go to since I bought the rifle. The guy that owns it is friendly and helpful. I think that the first target starts at 300 yards. But then there is another place I've heard about just south of Fort Wayne, IN. i'de like to check out too. The point is... I'll take those longer shots and record them like you said hopefully this summer.

I'de also like to compare some other bullets with the 250 gr. Federal Partion I've been shooting. I really don't plan on goin any lower than a 250 gr. So it narrows my selection down a little. That's ok I guess.

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Just for a thought for you.

Just for a thought for you. In my .340 Weatherby I have tried just about all the bullets out there. I have settled on two of them. One is the Barnes 185 grain XLC boat tail at 3400 fps they have discontinued this bullet and I am hording my last 200 of them. The round that I now do most of my hunting with out of the Weatherby is the Barnes 225 grain TSX bullet at 3000 fps. That bullet and my Weatherby is a match made in heaven.

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Everything everyone has said

Everything everyone has said is all spot on. Being able to shoot all planned distances and seeing real world results is the best thing. If you can't you really need to chronograph the load your using to accurately punch in data. I've been using one all summer and advertised velocities have been off by over a hundred fps in both directions depending on loads. The best bullet I've found in numerous calibers has been the Barnes TSX and the TTSX. After multiple others in factory and handloads it's the only bullet that will shoot an inch in my 35 Whelen. Most are far worse. But unlike the other guys I use the Leupold CDS system on 3 rifles and turn turrets a lot. Fast and accurate I've taken animals from 100 to over 500 yards in the last year.

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I have a Pact Mk IV

I have a Pact Mk IV cronograph with a trajectory function. I have checked it for accuracy against Hornady calculations and it is exactly on. I used Hornady because that the bullet's I use to hunt when I do.

The difference in BC's is not near so dramatic as anyone thinks in shooting long range. I have taken the BC's that were posted, used a 200 yd sight in with zero off set at 200 yds. Have a very old Speer manual I got a velocity for a 250gr bullet from a 338 win mag and here's how it looks.

 

BC.521

100yds            +2.0"

200yds            +/-o"

300 yds           -8.1"

400yds            -23.5"

500 yds            - 47.0"

 

BC .473

100yds            +2.1"

200yds            +/-0"

300yds            -8.4"

400yds            -24.2"

500 yds            -48.9"

 

BC .458

100yds            +2.1"

200yds            +/-0"

300yds            -8.5"

400yds            -24.6"

500yds            -49.7"

At this point the difference between the high BC of .521 and the BC of .458 only has a difference in drop at 500yds of 2.7". Well less than minute of angle. The velocity favor's the .521 BC at 1907.6 fps vrs .458 at 1811.2 fps. less than 100fps at 500yds. Going on to the .431 BC.

,431 BC

100yds            +2.2

200yds             +/-0"

300 yds            -8.7"

400yds            -25.1"

500yds            -51.0"

 

So from the high BC of ,521 to the low BC of .431 there is still less that one min of angle difference. And less than 150 fps in velocity. Even though the BC's seem to say one thing, they are not so dramatic as they seem! When I first discovered this it blew my mind. How could it be no more different than that? Do the math and the difference is only .09, that's not a hell of a lot when looked at that way. High BC's sell bullets that are all but equal in most every other way.

Here's another little bit that might be hard to accept. The difference in rise at mid range.

rise at mid range, 250yds

.521            -3.2"          remaining vel  2284.9 fps

.473            -3.3"                              2245.0 fps

.458            -3.3"                              2230.8 fps

.431            -3.4"                              2202.7 fpws

Difference in velocity of only 82.2 fps. That is not a whole lot of advantage to a bullet with what seem's to be a lot higher BC. It's because of that I can take th BC of a different but similar bullet, work up the data and shoot for the true trajectory. I did these up in 50 yds increment's from 50 yds to 500 yds. My system will take it down to 1 yd increments I think. I've only taken it to 25yd increments. Point is don't be overly impressed with high BC. 

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