is MOA proportional to distance?

[gphil]

I've always thought that MOA was proportional to the distance, for instance if your shooting 1MOA consistantly at 100 yards then you will shoot 1MOA at 500 yards which would be 5 inch groups. A guy told be this isnt neccessarily the case the other day and i was wondering if i could get some more opinions.

 

[Oliveralan]

MOA is minute of angle with is a degree measurement and therefore proportional to distance. However a rifle that shoots 1 moa at 100yards, does not mean it will shoot 1 moa at 500 in real world conditions. This is because factor such as wind, velocity spread, etc become more significant.

 

[gphil]

so if im shooting 1 MOA at 100yds consistently with no wind will my best achieveable group at 500yds be 5 inches?

 

[huntinco]

You could still get lucky and shoot a 5" group @ 500 as your velocity spreads are just strating to annoy you at that distance. Now take that out to 1000+ and velocity spreads will become your worst enemie. Now take what I call the G curve ball a velocity that plus or minus 30 fps of your standard deviation with a misjudgment of 5mph cross wind at distances beyond 1000 and you have a total miss and a bunch of cuss words!!!!

 

[Scot E]

There are a lot of answers to that question and they are going to take you both ways. For example, if you shoot BT bullets then you may find that you groups actually shrink at 200 yards and beyond compared to your 100 yards groups. Most boat tail bullets take some time to stabilize and one usually finds best groups at or past 200 yards.

When you start to extend things out past 5-600 yards then you start to see other issues show up like velocity variances from shot to shot that will begin to open up those groups if you don't have your reloads really dialed in.

Barrel twist can also affect things as well as other issues.

Scot E.

 

[charles bonner]

In the online store they sell a very good book-Applied Ballistics For Long-Range Shooting by Bryan Litz.In the book he goes into great detail that Explain how bullets can be expected to perform under many conditions.The mathmatics are beyond my comprehension;but the bullet BC information and program are worth the price of admission.
Some shooters myself included have rifles that seem better(MOA) at longer ranges.I've heard this described as the bullet going to sleep(stabilizing) at longer ranges.Fact or wives tale I do not Know.I think for me this book was a good investment.I'm leaving in the morning for some long range coyote shooting and the book will be my light reading around the camp fire.Maybe I'll get smarter the second time I read it.

 

[gphil]

alrlight thanks for the help everyone and goodluck yote hunting! Ill look into that book and ill hopefully get to do some shooting this weekend myself!

 

[LRSickle]

There are a lot of answers to that question and they are going to take you both ways. For example, if you shoot BT bullets then you may find that you groups actually shrink at 200 yards and beyond compared to your 100 yards groups. Most boat tail bullets take some time to stabilize and one usually finds best groups at or past 200 yards.

When you start to extend things out past 5-600 yards then you start to see other issues show up like velocity variances from shot to shot that will begin to open up those groups if you don't have your reloads really dialed in.

Barrel twist can also affect things as well as other issues.

Scot E.

I think Scot summed this up perfectly. I've seen this many times with boatails.

 

[Sully2]

I've always thought that MOA was proportional to the distance, for instance if your shooting 1MOA consistantly at 100 yards then you will shoot 1MOA at 500 yards which would be 5 inch groups. A guy told be this isnt neccessarily the case the other day and i was wondering if i could get some more opinions.

Shooting consistency and visual MOA are two separate "critters". MOA is most defiantly proportional...meaning..1" @ 100 yds will be 5" @ 500 yds...BUT...what you and your rifle can shoot is entirely different. You might be able to shoot 1" at 100 yds...but for various reasons you shoot 24" groups at 500 yds!!!

 

[Long Time Long Ranger]

Like others stated many factors come into play. MOA obviously is proportional. If it wasn't dialing the proper MOA to your long distance target wouldn't work. As far as groups it is a different story. If you have a good rifle the groups will actually shrink proportionaly as the range increases to a certain point where velocity spreads, etc factor in. When a bullet leaves the muzzle it travels in an eliptical orbit around the centerline of your bore. To visualize this understand your rifle is not throwing a bullet left, then right, then low and then high of the others to produce a group. Your group is the bullets printing at different points along this elliptical orbit around the center of your bore. When it hits the paper it will always be somewhere within this predictable orbit. That is your group size if you take out shooter error and a few other variables. Now this orbit will shrink as the range increases to the point this orbit will become proportionally very small in relation to distance. That is why my baby 338-378 rarely shoots under 1" groups at 100 yards but will shoot 7.5" at 1000 yards. Considering velocity spreads and operator error that means the bullet is stabilizing around the centerline of the bore.

Unfortunately as the distance to target increase and time of flight increases as your bullet slows exposing it to the elements of atmospheric conditions and gravity along with velocity spreads causing bullets to drop at different rates your groups begin to spread disproportionately. Then take into effect spin drift, correolis effect, case and bullet differences in weight and capacity, BC not exact, angle to target, etc, etc and you begin to wonder how in the hell did I make that shot at a mile.

These are the reasons I draw the line between long range shooting and long range hunting. Animals are very precious to me and I have deep respect for them I guess coming from my Indian heritage. So I draw the line on shooting at something to see if I can hit it versus shooting at something I am 99% sure I will kill it. That range varies with conditions but rarely exceeds 1000 yards. That is why most of my rifles are set up with components making them the best they can be to a half mile because usually I can stalk to within that. Sometimes I can't and this year hit some 900-1100 yard one shot kills when the conditions allowed me to be certain of those shots.

 

[gphil]

ok thaks that makes sense to me and answers my question perfectly. I just got my gun sighted in well today and chronographed so ill have to start testing my skills. My setup isnt capable of 100yd shots by any means but i would be happy if i could shoot MOA to 600yards repeatibly. thanks again for the guidance that throroughly answered my question.