Randy,
I down loaded the free trail version and started to play with it. They use something called a C1 drag model. This ballistic model is in none of my ballistic books.
You cannot changed drag models as it only uses a C1 drag model. Therefore the ballistic calculations treat all bullets regardless of type, shape or design the same.
I took their example ballistic data and ran my own numbers. They are simply using Mayevski Ingalls G1 drag model. The Mayevski Ingalls drag model is based on a 100+ year-old calculation using a 1 inch 1 pound round nose projectile as its basis. So what Horus is really saying…. any type of bullet regardless of shape can be calculated using the same mathematical model.
So if I have a two different bullets with very close BC's, say a 600 grain .458 barnes round nose spire point bullet with a published G1 BC of .454 and a 160 grain .284 cal sierra spitzer BT with a published G1 of .455, both leaving the muzzle at 2600 per second they are going to have the same aerodynamic flight characteristics. I think not! That's not rocket science!
I've run into many shooters who have evaluated the Horus system in some of the tactical competitions I've competed in. Bottom line from their perspective, it sucks. Out to 400 yards it works fine, but beyond that it's a crapshoot and doesn't work as advertised.
I've been able to use Pejsa's program to match my actual data on my loads very accurately. You just have to play with the retardation coefficient on his program, which is pretty simple and straightforward.
Hope it helps
