How do I convert inches drop to holdover?

tpcollins · June 15, 2017, 07:13 AM

I apologize this is not a firearms question but I value the knowledge on this forum.

With a 30 yard zero on my crossbow, the drop at 40 yards is 5". (That does convert to about 12.5 MOA). If I use a holdover or Kentucky windage, would I aim 5" higher on the target to hit it at 40 yards? Sorry I'm just having a mental block.

tobnpr · June 15, 2017, 07:17 AM

Drop isn't linear, but if the dope is correct- yes, you would.

(You're stating that the drop over the 10 yards beyond your zero is 5", so you would hold 5" high). Always best to confirm this in the field for your bow- not a bow user, but you can't rely on "published" data to be correct as variables such as your arrow velocity can vary I'm sure.

PlatinumCore16 · June 15, 2017, 02:07 PM

So I used to bow hunt, haven't taken it out of the case in over a year

BUT yes, that is correct. The farther the distance the arrow, bullet, projectile has to fly, the higher you have to aim. Obviously you get to a point where you run out of elevation, but that's the idea. The thing about bow/crossbow hunting, especially, is that our projectile is a much slower object than firearms and has much greater wind resistance. So the drop will be much more exaggerated.

Had written more, but it was out of scope of your original question.

tpcollins · June 16, 2017, 06:47 AM

Thanks for the replies, I wasn't sure because I had MOA clicks up on the brain and was thinking shooting under 100 yards might be calculated different.

My .204 when zeroed at 100 yards has a 1.4" drop or .7 MOA at 200 yards. That's about 3 clicks up on my scope's turret to hit the target at 200 yards.

I was confused about any difference between moving the crosshair up via the elevation turret versus moving it up via holdover. I assume when using a holdover I would just aim 1.4" high as well?

I know the 3 clicks up is 1.4" at 200 yards, I was just trying to understand if it was on the same angle as the holdover. Thanks.

g.willikers · June 16, 2017, 08:56 AM

The best way to find the longer distance holdover with your equipment is just shoot it and see where it lands.
While the amount of holdover might be as expected,
There's only one way to find out exactly if there are any idiosyncrasies with your own particular setup and your style of shooting.

T. O'Heir · June 16, 2017, 11:35 AM

MOA isn't about trajectory. It's a measurement of group size.
"...aim 5" higher on the target to hit it at 40 yards..." It should, but there's arrow weight involved too. Heavier arrows drop less.
Mind you, most deer are about 36" from brisket to shoulder. And the heart is at the bottom behind the legs, side on. A 5" drop might not matter. Issue would become penetration though.

tpcollins · June 17, 2017, 01:29 PM

Quote:

Originally Posted by T. O'Heir

MOA isn't about trajectory. It's a measurement of group size.

Well that just confused me, I thought MOA was an angular measurement and a sub-MOA group size meant it was less than 1.047" at 100 yards.

Unconventional · June 20, 2017, 01:05 PM

You're correct, tpcollins; MOA (minute of angle) is a measure of angle. It can be used to measure group size. Just like the "inch" can measure a multitude of things, a minute of angle can be used for more than just group size - though it is often used for that purpose.

June 15, 2017, 07:13 AM	#1
tpcollins Senior Member Join Date: February 18, 2009 Location: SE Michigan Posts: 558	How do I convert inches drop to holdover? I apologize this is not a firearms question but I value the knowledge on this forum. With a 30 yard zero on my crossbow, the drop at 40 yards is 5". (That does convert to about 12.5 MOA). If I use a holdover or Kentucky windage, would I aim 5" higher on the target to hit it at 40 yards? Sorry I'm just having a mental block. __________________ What direction did that last shot at Kennedy come from?

June 15, 2017, 07:17 AM	#2
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	Drop isn't linear, but if the dope is correct- yes, you would. (You're stating that the drop over the 10 yards beyond your zero is 5", so you would hold 5" high). Always best to confirm this in the field for your bow- not a bow user, but you can't rely on "published" data to be correct as variables such as your arrow velocity can vary I'm sure. __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com Last edited by tobnpr; June 15, 2017 at 07:22 AM.

June 16, 2017, 06:47 AM	#4
tpcollins Senior Member Join Date: February 18, 2009 Location: SE Michigan Posts: 558	Thanks for the replies, I wasn't sure because I had MOA clicks up on the brain and was thinking shooting under 100 yards might be calculated different. My .204 when zeroed at 100 yards has a 1.4" drop or .7 MOA at 200 yards. That's about 3 clicks up on my scope's turret to hit the target at 200 yards. I was confused about any difference between moving the crosshair up via the elevation turret versus moving it up via holdover. I assume when using a holdover I would just aim 1.4" high as well? I know the 3 clicks up is 1.4" at 200 yards, I was just trying to understand if it was on the same angle as the holdover. Thanks. __________________ What direction did that last shot at Kennedy come from?

June 16, 2017, 08:56 AM	#5
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	The best way to find the longer distance holdover with your equipment is just shoot it and see where it lands. While the amount of holdover might be as expected, There's only one way to find out exactly if there are any idiosyncrasies with your own particular setup and your style of shooting. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

June 16, 2017, 11:35 AM	#6
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	MOA isn't about trajectory. It's a measurement of group size. "...aim 5" higher on the target to hit it at 40 yards..." It should, but there's arrow weight involved too. Heavier arrows drop less. Mind you, most deer are about 36" from brisket to shoulder. And the heart is at the bottom behind the legs, side on. A 5" drop might not matter. Issue would become penetration though. __________________ Spelling and grammar count!

June 15, 2017, 02:07 PM	#3
PlatinumCore16 Senior Member Join Date: February 23, 2017 Location: Colorado Posts: 424	So I used to bow hunt, haven't taken it out of the case in over a year BUT yes, that is correct. The farther the distance the arrow, bullet, projectile has to fly, the higher you have to aim. Obviously you get to a point where you run out of elevation, but that's the idea. The thing about bow/crossbow hunting, especially, is that our projectile is a much slower object than firearms and has much greater wind resistance. So the drop will be much more exaggerated. Had written more, but it was out of scope of your original question.

June 20, 2017, 01:05 PM	#8
Unconventional Member Join Date: February 27, 2017 Posts: 81	You're correct, tpcollins; MOA (minute of angle) is a measure of angle. It can be used to measure group size. Just like the "inch" can measure a multitude of things, a minute of angle can be used for more than just group size - though it is often used for that purpose. __________________ Unconventional