Determining "Recoil Efficiency"

solarshooter

Lil-Rokslider
Joined
Jan 17, 2023
Messages
249
Location
WA
I have shown some calcs in the past where I've done point assessments of certain cartridges/bullets/rifles to try and determine what is the lowest recoil way to get a certain wind number. Today I decided to elaborate on this a bit and assess recoil and wind number as a function of MV and caliber.

First, I created a reference bullet for each caliber which has a weight and BC representative of the highest performing bullets in that caliber.
1736628403826.png

I then estimated powder charges needed to get that bullet to the given MV in a roughly 20" barrel. This is cartridge agnostic, and may not be perfect. I use this in conjunction with bullet momentum to calculate total recoil.
1736628455741.png

I then calculate recoil in a 9lb rifle, run the bullet at the given speed to determine the wind number, and finally calculate wind# per recoil.
1736628543106.png

The way I would use this chart is to narrow in on what bullet at what speed gives you your desired performance and what the "recoil efficiency" of that combination would be. You could then pick your barrel length and cartridge to get you that performance target. For instance, if you ask what is the minimum recoil way to get an 8mph wind number gun, the answer is a 6mm bullet at 3200fps or so, aka a 6UM. It also shows you the recoil INefficiency of larger calibers - moving up in weight is almost always less recoil efficient than going faster.
 

KyleR1985

WKR
Joined
Jul 28, 2019
Messages
731
For the ballistically challenged, a wind number is:

Bullet X moving at Y speed gives you ______________ performance in Z mph wind.

Can you fill in the blank, or correct the back of class guy?
 

wind gypsy

"DADDY"
Joined
Dec 30, 2014
Messages
10,099
For the ballistically challenged, a wind number is:

Bullet X moving at Y speed gives you ______________ performance in Z mph wind.

Can you fill in the blank, or correct the back of class guy?

Its the wind speed at which a wind hold correlates 0.1 mil per 100 yards.

EX: 5 MPH gun or 5 MPH wind # with a 90 degree 5 MPH wind would have the following wind holds

300 yds - 0.3 mil
400 yds - 0.4 mil
500 yds - 0.5 mil
600 yds - 0.6 mil

Doesn't typically go to infinity but is a good quick way to figure wind corrections at reasonable distances.
 

KyleR1985

WKR
Joined
Jul 28, 2019
Messages
731
Its the wind speed at which a wind hold correlates 0.1 mil per 100 yards.

EX: 5 MPH gun or 5 MPH wind # with a 90 degree 5 MPH wind would have the following wind holds

300 yds - 0.3 mil
400 yds - 0.4 mil
500 yds - 0.5 mil
600 yds - 0.6 mil

Doesn't typically go to infinity but is a good quick way to figure wind corrections at reasonable distances.

Awesome thanks.
 
Joined
Mar 25, 2013
Messages
689
Location
Alberta
excellent, what about another look (and it maybe it overlays this efficiency?) of 'most bc per gr of bullet weight' efficiency, and what diameter that generally lands on?

we might be able to finally find the end of this lrh road to the perfect most efficient choice lol (of what is most efficient blend of copper/lead bullets currently available, maybe it will help drive future development paths?)
 
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