Chronograph and other questions?

[chasethomas]

I am going to be picking up a chronograph and getting the average velocity my rifle shoots my 280ai so I can input that info into a ballistics calculator. I have 2 questions on this.

1. I know altitude affects a lot of things with ballistics but does it effect the intial velocity to the point I need to check my velocity at 9k feet hunting elevation if my range is only 1k feet elevation?

2. What is everyone's favorite ballistics calculator? I do not handload but my rifle loves hornady 162 eldx's I am getting 1/2" groupings with them.

 

[Pickettpuncher]

Question1, yes, it affects it.

Question 2, strelok and I think the other is ballistic advantage? I use strelok, not the ballistic app

 

[mxgsfmdpx]

Be sure to field verify hits at ranges before just putting data in an app and shooting at animals. Very important step that many seem to forget.

 

[JFK]

Altitude doesn’t impact MUZZLE velocity in a meaningful way. Temperature can and will impact powder burn and muzzle velocity. Altitude will impact down range bullet flight as the air is thinner with less resistance as you go up. POI will typically be higher as you go up in altitude if temp is comparable to where you developed the load. Lower temps can create lower muzzle velocity but I’ve never noticed anything drastic and this will largely be dependent on the powder. If you have the time on your hunt by all means bring a chrono and get an updated velocity. I develop loads at lower elevations, adjust temp and altitude in the app as a starting point, then shoot to verify zero and drops at higher altitude. Long story short, you have to verify everything when you go up in elevation.

I have strelok, shooter and the ballistic app. They all work, and I’ll actually use two sometimes to see if they match.

 

[Harvey_NW]

I use Strelok also. Couple things to note, even with a chrono you'll have to tune your calculator at distance. With factory ammo just use the box velocity and BC, shoot one at 300 and 600 and adjust velocity until they match POI, take it out to 1,000 and adjust velocity and BC accordingly.

Second, you can set a temp sensitivity factor in Strelok. You'll have to physically shoot at the 2 different temperatures, or simulate by throwing a few rounds in a sandwich bag and a cooler with ice, and a couple in your pocket, single feed and shoot each quickly without letting it stabilize or cook in the chamber, record the avg's in the app.

 

[seand]

I am going to be picking up a chronograph and getting the average velocity my rifle shoots my 280ai so I can input that info into a ballistics calculator. I have 2 questions on this.

1. I know altitude affects a lot of things with ballistics but does it effect the intial velocity to the point I need to check my velocity at 9k feet hunting elevation if my range is only 1k feet elevation?

2. What is everyone's favorite ballistics calculator? I do not handload but my rifle loves hornady 162 eldx's I am getting 1/2" groupings with them.

1. No your powder charge isn’t changing so muzzle velocity is the same

2. JBM ballistics online. You won’t be ready to shoot any father than a paper printout will get you - Assuming you aren’t doing ELR with factory ammo and not a lot of experience.

Your initial velocity isn’t critical to build a dope card. Zero at 100, get your dope at 500 or 600 by shooting. Plug into JBM using the elev/temp you shot when getting dope. Tweak velocity in JBM until it matches your dope. Change elev/temp to what you expect in your hunt, and print dope card.