Major Change in Sighted In Yardage

[rkittine]

Not sure where this should be posted, but here goes. Probably a simple answer that I should know as a graduate engineer, but I though people here could help me quicker that I could figure it out. I am a newbie to all of this.

New Rifles
6.5x47L
6mmBR Norma
.308

All started with 0 MOA bases

All bore sighted for 100 yards and then sighted in at 100 yards.

Now changing to 20 MOA (I believe that is what I need) on one rifle and I have Burris Signature Z Rings with inserts on the others.

What procedure do I use now to get on paper at 1,000 yards?

Thanks, Bob

 

[mac86951]

Simple answer, sight in at 1000.

Better answer, assuming no changes and unlimited adjustment, a scope on a 0 rail will just need vertical adjustment. How much? Use a ballistic calc, feed in your bullet and velocity and done, you're on paper.

Add a 20minute rail, and you'll have to re sight in. Distance change from bore axis means 100y zero shifted (ideally it would be 20Min adjustment, but there are other factors too). All the 20MOA rail does is to give you an extra 20MOA in elevation.

I'm leaving out a ton of details, I'd suggest you do a search. FYI, this is far simpler that you think. As an engineer you'll know that degrees of angle are subdivided into minutes, seconds, ... all were talking about here are minutes of angle (MOA).

-Mac

 

[savagedasher]

Simple answer, sight in at 1000.

Better answer, assuming no changes and unlimited adjustment, a scope on a 0 rail will just need vertical adjustment. How much? Use a ballistic calc, feed in your bullet and velocity and done, you're on paper.

Add a 20minute rail, and you'll have to re sight in. Distance change from bore axis means 100y zero shifted (ideally it would be 20Min adjustment, but there are other factors too). All the 20MOA rail does is to give you an extra 20MOA in elevation.

I'm leaving out a ton of details, I'd suggest you do a search. FYI, this is far simpler that you think. As an engineer you'll know that degrees of angle are subdivided into minutes, seconds, ... all were talking about here are minutes of angle (MOA).

-Mac

Zero at 100 Your guns will need 32to 36'' of inches of bullet rise above the point of aim .
Larry

 

[Tim Singleton]

Hopefully there is a sandy berm behind your 1000 yd target
The elevation is just checking velocity with the bullet used
Windage can be the bite. If the bases are out just a bit it's hard to find your hit. Have a spotter to help

 

[savagedasher]

Hopefully there is a sandy berm behind your 1000 yd target
The elevation is just checking velocity with the bullet used
Windage can be the bite. If the bases are out just a bit it's hard to find your hit. Have a spotter to help

My gun shoots flatter when I sight in for1000 with a 100 I keep the aim at 100 and move the crosshairs Down to a 27" mark below the hundred yard . You will 30 to 32 " . Larry

 

[hogpatrol]

I would get a good ballistics program. I have the Applied Ballistics one and with exact inputs, it works very well out to 1000.

 

[rkittine]

A friend ran it for me on his JBM Software. Looks like for my current loads for 100 yards, I will need 27.35 MOA increase to get into the ballpark.

Bob

 

[6MMsteve]

with a 308 Baer shooting 220SMKs my zero was 26.5in for 1022 yards when I shot at Penn 1000yd Bench club, vel 2950 84.5 grs 7828 30 or so inches should put u on paper 308 lot more maybe depends on bullet wt. Penn 1000 is a few yards longer 1022

 

[6MMsteve]

I would start at 27in and go from there, but you will need 1000yds measured exact if you want to be sure, don't do like we did and step it off then go to Penn 1000 club and not shoot on Saturday and can't get on paper sunday, We went directly to our range when we got home and done some lookin and measuring what we thought was 1000 but it was like 890, of course everything has changed since then, computers and the lot, plus light & heavy gun but we made up for it the next time up.

 

[6MMsteve]

Have fun

 

[rkittine]

Gives me something to do with all my free time. Now if I could just retire!

I will do this at Williamsport where I am a member. The berm is 1,040 and the target holders are at 1,000.

Bob

 

[HTSmith]

Bob, I'll tell you what I did, but I'm certainly not a rocket surgeon. I only had access to a 100 yard range prior to going to my first 1000 yard match. I used the JBM calculator that is free on line. A key variable is the height of your sights above the bore. My method was using a tight fitting bore guide, dial calipers and measuring outside to outside the distance from the bottom of the bore guide to the top of the scope bell. Then subtract half the diameter of the bore guide and scope bell to get a center to center measurement. I had to guestimate my muzzle velocity, but I ended up being real close. (Obviously a real chrono'd measurement is best). Set the zero distance to 1000 and it will give you your come up from 100 yds in moa. For sanity check the number will should be in the range others have suggested-- 25 to 35 MOA

My number for my 6BR calculated 31 MOA. My first sighter shot was a 9 high. I didn't even to expect to hit the target. I came down 1 to 30 MOA and was dead on for elevation in the 10 ring. (From this start I went on to prove I had no clue about the wind, but it sure was fun). It could have all been dumb luck but I would recommend starting with comeups from this model.

I used the offset Burris inserts and they worked great.

BTW you sure have some nice hardware. I'm jealous.

 

[XTR]

I can't speak to the others, but with the 308 depending on bullet and muzzle velocity you will need 32 to 36 MOA to get to 1000 yards.

If you are using factory ammo, figure the 36MOA number, the 32MOA number is closer to what experienced F-TR shooters with 30" barrels and warmish loads running high BC bullets need.

 

[rkittine]

I think as long as I have a spotter and start out on the low side to be safe and not overshoot, I should be able to talk it in.

Bob

 

[XTR]

I can tell you what the USMC spotters do at Camp Perry, they have you take 6 or 12 MOA off and watch in the scope for the dirt splash, then they dial you in. They get guys on paper pretty quickly.

The other thing to do is to have a spotter with a good scope with you to watch the trace.