How to Calculate Down Range Effectiveness

[gtthorne]

Is there a formula for calculating FPS and FT Pounds at a certain distance? I have a chronograph that is giving me the muzzle velocity and ft lbs. Let's say I have a 25 gr slug that is leaving the barrel at 870 fps and 42 ft lbs. What would these figures be at 50 yards? I have an 18gr pellet that leaves the muzzle at 990 fps with 39 ft lbs. I'm wondering if at 50 yards this could cleanly put down a Rabbit, Squirrel, Head shot Woodchuck. Can this be calculated or do I need to put a chronograph at the point of impact?

 

[CTAirgunner]

Personally when I am setting up a rifle I use these two calculators to determine if my theoretical setup is going to perform remotely close to how I want it to in real time,

The first link will do what you want it to do

Ballistics Calculations

The second one I like to use to figure out what the rifle specs need to be in order to shoot the round I want to shoot.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

Also good job on trying to be aware on energy down range!

 

[gtthorne]

Thanks for the Ballistic Calculations link. This is interesting and I will play with it more. But this makes me feel a little more comfortable about taking a humane shot at least at 50 yards. Not sure I'll need to take shots further out but at least if I do, I'll know what my pellet should be doing and I would be comfortable with it. I'm not familiar with some of the info being requested in the twist rate calculator, but again I will play with this. Thanks for these useful utilities.

 

[CTAirgunner]

Thanks for the Ballistic Calculations link. This is interesting and I will play with it more. But this makes me feel a little more comfortable about taking a humane shot at least at 50 yards. Not sure I'll need to take shots further out but at least if I do, I'll know what my pellet should be doing and I would be comfortable with it. I'm not familiar with some of the info being requested in the twist rate calculator, but again I will play with this. Thanks for these useful utilities.

Thats how I learned, I played with the berger link for a couple days and boom now its second nature.

50 yards should be more than fine, I have taken a pigeon atop a silo at 60 yards with a 26 fpe muzzle energy rifle and even one at roughly 80.... @AirGunAddictsAnonymous was there and he took one at 82! he had a little more energy than I but roughly the same as you.

 

[PA_AirHead]

Thats how I learned, I played with the berger link for a couple days and boom now its second nature.

50 yards should be more than fine, I have taken a pigeon atop a silo at 60 yards with a 26 fpe muzzle energy rifle and even one at roughly 80.... @AirGunAddictsAnonymous was there and he took one at 82! he had a little more energy than I but roughly the same as you.

I use my Strelok Pro app that is no longer avail due to the political BS over their. In that app it gives the energy level expected based on FPS and the BC of the projectile. And that 82 yd shot was amazing to perform. That was out of my AEA Element R shooting the 25 gr Hades pellet.

 

[CTAirgunner]

I use my Strelok Pro app that is no longer avail due to the political BS over their. In that app it gives the energy level expected based on FPS and the BC of the projectile. And that 82 yd shot was amazing to perform. That was out of my AEA Element R shooting the 25 gr Hades pellet.

Looking forward to another day like that!

 

[PA_AirHead]

Looking forward to another day like that!

When it’s a little cooler out

 

[IRBent]

Personally when I am setting up a rifle I use these two calculators to determine if my theoretical setup is going to perform remotely close to how I want it to in real time,

The first link will do what you want it to do

Ballistics Calculations

The second one I like to use to figure out what the rifle specs need to be in order to shoot the round I want to shoot.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

Also good job on trying to be aware on energy down range!

I was looking at that Berger Twist rate calculator this weekend and was wondering how good it is for us airgunners. What I seem to recall was it was saying that I needed speeds on pellets for my 17.7 twist rate that exceed the typical known speed limits, in excess of 890, or even 1000fps. Like .22 cal JSB 18.13s at 990fps on a 17.7:1 twist rate is claiming to be marginally stable, but jack the speed up to 1100 fps and the calculator seems to like that better. In real life, does this calculator actually work for pellets?

 

[CTAirgunner]

I was looking at that Berger Twist rate calculator this weekend and was wondering how good it is for us airgunners. What I seem to recall was it was saying that I needed speeds on pellets for my 17.7 twist rate that exceed the typical known speed limits, in excess of 890, or even 1000fps. Like .22 cal JSB 18.13s at 990fps on a 17.7:1 twist rate is claiming to be marginally stable, but jack the speed up to 1100 fps and the calculator seems to like that better. In real life, does this calculator actually work for pellets?

It works for slugs. That's as far as I know.