600 yard Dope

[Iowashooter]

I went out to the farm yesterday to practice out to 600 as I hadn't shot past 300 and have a match coming up with 500 and 600 targets. I am shooting hornady 68 gr bthp match bullets over varget. my elevation marks were pretty much spot on in my burris xtr II 1.5-8x28 out to 500 but when I got to 600 my bullet impact was almost 3 feet low. Using my mark for 700 would put it almost right on.

Keep in mind I was shooting in iowa in 20 degree temps. My match will be in central misouri in 2 weeks so likely 50-65 degree temps day of the match.

My question is why the elevation difference between 500 and 600? And what velocity change can I likely expect with varget as it warms up? 18" nordic barrel.

[bwikel]

My experience has been that Varget is temperature insensitive. Do you feel confident in the velocity number you used for your hold overs? I am assuming you are using ballistic software to determine your holds?

[Shooter115]

Varget not very temp sensitive. If you were working up loads in -20 and were going to Phoenix to shoot a match it might make a small difference. In your case you got nothing to worry about. BDC reticles are tough to get right at distance, once you get out past 500 yards just the slightest change in velocity makes a huge difference.

[dauntedfuture]

I think you are saying that you dialed your scope for 500 and it was right on, then from 500-600 you were 36" low. 36" low is 6 MOA. I suspect that this is a combination of you not shooting the bullet that the scope is calibrated for and or a delta in velocity. I also suspect that you were shooting at steel and not an NRA type of target. The only way to know you were really 36" low would have been to keep holding center and come up 6 MOA. If you were holding on the 700 but hitting 600, its hard to know exactly how high/low etc you are. To keep things in perspective the bullet drops about as much from 300-500 as it does from 500-600. This is all to say, unless you know, you might have been hitting not quite 36" low, combine this with a bullet that drops faster than what the BDC is made for an a 100-200 FPS less load.

In general the BDCs are usually pretty close but they are not exact unless you are shooting the exact load the BDC is made for. There are also environmental factors that play into things. A headwind can make a 1MOA difference.

Of the 68-69g bullets out there the 68 has a far worse BC then a 69 SMK does. The Lapua is even better and now with the 69TMK, that bullet takes the cake when it comes to BC.

Also, unless you shot 300 and then to 600 on the same day at the same range your scope could have moved a little.

[Iowashooter]

I think you are saying that you dialed your scope for 500 and it was right on, then from 500-600 you were 36" low. 36" low is 6 MOA. I suspect that this is a combination of you not shooting the bullet that the scope is calibrated for and or a delta in velocity. I also suspect that you were shooting at steel and not an NRA type of target. The only way to know you were really 36" low would have been to keep holding center and come up 6 MOA. If you were holding on the 700 but hitting 600, its hard to know exactly how high/low etc you are. To keep things in perspective the bullet drops about as much from 300-500 as it does from 500-600. This is all to say, unless you know, you might have been hitting not quite 36" low, combine this with a bullet that drops faster than what the BDC is made for an a 100-200 FPS less load.

In general the BDCs are usually pretty close but they are not exact unless you are shooting the exact load the BDC is made for. There are also environmental factors that play into things. A headwind can make a 1MOA difference.

Of the 68-69g bullets out there the 68 has a far worse BC then a 69 SMK does. The Lapua is even better and now with the 69TMK, that bullet takes the cake when it comes to BC.

Also, unless you shot 300 and then to 600 on the same day at the same range your scope could have moved a little.

The bdc on the scope is for a 62 gr m855. all the bdc markings were dead on until 500. There was about a 12-15 full value wind from left to right. I was shooting at a pallet with cardboard covered in shoot'n'see. I never fired a shot holding on the 7. But from where I was holding with the 6 my impact was right where my seven is. I shot 5 round group then drove the wheeler out and taped the target. I didnt put a tape feom poa to poi but my eyeball guess was 36". All shots were fired on the same day.

[Fordfan485]

Here is the general rule of thumb to get on paper with a nra highpower rifle target(72x72in)

First line is the adjustment in MOA to come up in 100 yard increments

2-2-3-3-4-4-5-5-6-6 MOA

-100-200-300-400-500-600-700-800-900-1000 yards

Also I don't use less than 77 gr bullets for anything over 500 yds. hope this helps

Edited March 3, 2015 by Fordfan485

[bushmeat]

To the OP, a chrono and Strelock would probably answer your questions better than educated guesswork of anybody here.

Still since you actually shot at 600 and now know your poi, I would say you're in good shape.

[kuduman]

BDCs suck. They are always set up for someone else's gun. Their bullet BC, their velocity-- and their height-over-bore.

None of those matter much until 300 yards. All are critical by 500, which is what you are seeing.

They aren't allowed on my guns. Dial for distance, and tape a chart on your gun.

[michael1778]

I think you are saying that you dialed your scope for 500 and it was right on, then from 500-600 you were 36" low. 36" low is 6 MOA. I suspect that this is a combination of you not shooting the bullet that the scope is calibrated for and or a delta in velocity. I also suspect that you were shooting at steel and not an NRA type of target. The only way to know you were really 36" low would have been to keep holding center and come up 6 MOA. If you were holding on the 700 but hitting 600, its hard to know exactly how high/low etc you are. To keep things in perspective the bullet drops about as much from 300-500 as it does from 500-600. This is all to say, unless you know, you might have been hitting not quite 36" low, combine this with a bullet that drops faster than what the BDC is made for an a 100-200 FPS less load.

In general the BDCs are usually pretty close but they are not exact unless you are shooting the exact load the BDC is made for. There are also environmental factors that play into things. A headwind can make a 1MOA difference.

Of the 68-69g bullets out there the 68 has a far worse BC then a 69 SMK does. The Lapua is even better and now with the 69TMK, that bullet takes the cake when it comes to BC.

Also, unless you shot 300 and then to 600 on the same day at the same range your scope could have moved a little.

I had missed the memo on the new Tipped MatchKing. Wicked!!