Subsonic and Bullet Drop Question

[kmk1012]

Sorry mods if this is in the wrong section, please move accordingly.

So, will a 45gr 22lr bullet have the exact same drop at 100 yards, 200 yards, etc as say a 700gr 50 cal bullet? Let's assume that both bullets are traveling at 1050 fps each. All things the same, just weight I'd think they would have the same bullet drop at any distance. I'm looking to standardize a couple firearms with the same scopes and would like to know if every one can be adjusted and shot the exact same, regardless of caliber. As far as the question the 22 and 50 were examples but I have several in between.

Read More

 

[ORhutner]

Sorry mods if this is in the wrong section, please move accordingly.

So, will a 45gr 22lr bullet have the exact same drop at 100 yards, 200 yards, etc as say a 700gr 50 cal bullet? Let's assume that both bullets are traveling at 1050 fps each. All things the same, just weight I'd think they would have the same bullet drop at any distance. I'm looking to standardize a couple firearms with the same scopes and would like to know if every one can be adjusted and shot the exact same, regardless of caliber. As far as the question the 22 and 50 were examples but I have several in between.

Get a Ballistics Calculator app for your pocket super computer. Much cheaper and easier. A couple to look into would be Applied Ballistics and Strelok. In this scenario you have a profile for every gun/ammo combo you wish and you can adjust for that days conditions and location.

In theory you could get things figured out to match your scenario but you are looking at a lot of time and effort. I assume you are talking about reloading here to specifically tweak ballistics to mimic the same drop across a wide range of calibers. What you will run into though is that a single variable could throw all your work out the window on any given day. Temperature, case fill, angle of firearm related to case fill, atmospheric conditions, elevation, change from lot to lot of powder, primers, etc.... The list goes on and on.

 

[VinnieBoomBah]

ShootersCalculator.com | Ballistic Trajectory Calculator

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

shooterscalculator.com

 

[kmk1012]

ShootersCalculator.com | Ballistic Trajectory Calculator

Calculates the ballistic trajectory of a bullet fired from a rifle, handgun or other firearm. Produces a ballistic trajectory chart and table that shows the drop, velocity, kinetic energy, windage, and trajectory of a bullet.

shooterscalculator.com

That's exactly what I needed, thank you. High-school gravity lessons state that it should all be equal but I know that metplat and several other factors play a role. I'm just looking to find some common ground so I can standardize the scopes and practice.

 

[slimmer13]

Sorry mods if this is in the wrong section, please move accordingly.

So, will a 45gr 22lr bullet have the exact same drop at 100 yards, 200 yards, etc as say a 700gr 50 cal bullet? Let's assume that both bullets are traveling at 1050 fps each. All things the same, just weight I'd think they would have the same bullet drop at any distance. I'm looking to standardize a couple firearms with the same scopes and would like to know if every one can be adjusted and shot the exact same, regardless of caliber. As far as the question the 22 and 50 were examples but I have several in between.

They would be the same in a vacuum. In the real world, the external ballistics will be different which will change the POI.

 

[solv3nt]

Use calculus. You can calculate it with derivatives, or you could download an app. Either one.

 

[TTSX]

Ballistic coefficient changes everything, it's not just mass and speed. Those .50 bullets you're talking about have a BC of 1 which is extremely high, I'll be generous and give that .22 bullet a BC of .2 so no, they will not have the same or even similar drop at any speed unless in a vacuum

 

[VinnieBoomBah]

Ballistic coefficient changes everything, it's not just mass and speed. Those .50 bullets you're talking about have a BC of 1 which is extremely high, I'll be generous and give that .22 bullet a BC of .2 so no, they will not have the same or even similar drop at any speed unless in a vacuum

VERY generous!

.22 Rimfire Ballistic Coefficients - Sierra Bullets

www.sierrabullets.com

 

[Certaindeaf]

They would be the same in a vacuum. In the real world, the external ballistics will be different which will change the POI.

Eureka!







Lool

 

[kmk1012]

Ballistic coefficient changes everything, it's not just mass and speed. Those .50 bullets you're talking about have a BC of 1 which is extremely high, I'll be generous and give that .22 bullet a BC of .2 so no, they will not have the same or even similar drop at any speed unless in a vacuum

Ok, but in real world, would a 100 yard comparison be worth talking about? If they are within say an inch at 100 yards and grow further apart a person could use some on the fly hold over.

 

[VinnieBoomBah]

JMHO but if the idea is to use the 22 as an unfordable (and less panful!) understudy to whatever lobs a 700 gr 50 cal bullet 'close enough' should be fine. I really doubt that anything you smack with the 50 will notice the +/- POI

 

[Ginocide]

That's exactly what I needed, thank you. High-school gravity lessons state that it should all be equal but I know that metplat and several other factors play a role. I'm just looking to find some common ground so I can standardize the scopes and practice.

Correct. Your basic physics ballistics equation can give you a prediction on a perfect system, but in the real world the factors you mention, along with surface area, mass, cross sectional density, geometry, etc. all work together to make a difference. This is summarized in a item called the "ballistic coefficient" (BC) that summarizes and estimates how these factors work together to make the projectile less efficient in sliding through the air. There are also different BCs that perform better or worse at the flight at supersonic vs subsonic, etc. It's an interesting rabbit hole to go down and research. Ballistic calculators will frequently have some standard BCs of projectiles of a given weight and style, and any self-respecting manufacturer of reloading components will give you a BC on a given projectile as well.

Have fun!

Edit: Oh, and just to clarify, it's not impossible to make one projectile nearly ballistically identical to another. It has been a common (but now mostly outmoded) technique to use small guns with projectiles designed to imitate big projectiles fired from larger ordnance: https://en.wikipedia.org/wiki/Spotting_rifle

 

[kmk1012]

Correct. Your basic physics ballistics equation can give you a prediction on a perfect system, but in the real world the factors you mention, along with surface area, mass, cross sectional density, geometry, etc. all work together to make a difference. This is summarized in a item called the "ballistic coefficient" (BC) that summarizes and estimates how these factors work together to make the projectile less efficient in sliding through the air. There are also different BCs that perform better or worse at the flight at supersonic vs subsonic, etc. It's an interesting rabbit hole to go down and research. Ballistic calculators will frequently have some standard BCs of projectiles of a given weight and style, and any self-respecting manufacturer of reloading components will give you a BC on a given projectile as well.

Have fun!

Edit: Oh, and just to clarify, it's not impossible to make one projectile nearly ballistically identical to another. It has been a common (but now mostly outmoded) technique to use small guns with projectiles designed to imitate big projectiles fired from larger ordnance: https://en.wikipedia.org/wiki/Spotting_rifle

I have looked into all those factors and know what they mean. I was looking possibly for a real world person with experience. I have the ability to load subsonic in 22-50 calibers with several calibers in between but just need to buy a chronograph. I'm just looking for close enough is close enough here. I'd like to pick up on of several firearms that have the same optic with the same sight picture and regardless of cartridge have a similar impact.

 

[Ginocide]

Well specifically, to make this kind of thing work, you need to match the muzzle velocity and ballistic coefficient match. The standard ballistics equations apply, and the ballistic coefficient (I believe) is a essentially a calculated and repeated deviance from ideal. I'm leaving the depth of my understanding now, but if everything I've said until now is true that means to make sure two projectiles fly on the same path, they would need the same muzzle velocity and the same ballistic coefficient.

This is where you run into a problem. The .50 is a very powerful cartridge compared to the vast majority of other "small arms". The self-proclaimed fastest .22LR in the world, the CCI COPPER-22 is only 1,850 fps compared to Hornady's A-MAX Match 50 BMG at 2,820. .17HMR gets closer in the 2,600s. A 50 BMG though can have an excellent BC though, in fact trying to sort Hornady's loaded ammunition by BC seems to show essentially nothing in its class (which surprised me given many of the boutique calibers like .338 LM). Alternatively, if you are looking to do variable loading, you could underload the .50 and do something unusual like slightly blunt it, but this gets pretty esoteric pretty quick.

This echoes what others (including yourself I believe) have said, but as has been said, when you're looking at a specific range, this may not matter to you. Many NATO militaries used bullets made of wood and plastic because for the type of training and distance they were doing (familiarization under 100m) the difference was more or less negligible. Most rifle projectiles

So I guess I don't have a SPECIFIC answer. If you're looking to make several rifles with optics and projectiles calibrated to impact similarly at a single specific range, you can basically do this by zeroing all the guns' optics at that distance; problem solved. The problem though is they will only match at that specific distance, because the other factors don't match.

 

[kmk1012]

Well specifically, to make this kind of thing work, you need to match the muzzle velocity and ballistic coefficient match. The standard ballistics equations apply, and the ballistic coefficient (I believe) is a essentially a calculated and repeated deviance from ideal. I'm leaving the depth of my understanding now, but if everything I've said until now is true that means to make sure two projectiles fly on the same path, they would need the same muzzle velocity and the same ballistic coefficient.

This is where you run into a problem. The .50 is a very powerful cartridge compared to the vast majority of other "small arms". The self-proclaimed fastest .22LR in the world, the CCI COPPER-22 is only 1,850 fps compared to Hornady's A-MAX Match 50 BMG at 2,820. .17HMR gets closer in the 2,600s. A 50 BMG though can have an excellent BC though, in fact trying to sort Hornady's loaded ammunition by BC seems to show essentially nothing in its class (which surprised me given many of the boutique calibers like .338 LM). Alternatively, if you are looking to do variable loading, you could underload the .50 and do something unusual like slightly blunt it, but this gets pretty esoteric pretty quick.

This echoes what others (including yourself I believe) have said, but as has been said, when you're looking at a specific range, this may not matter to you. Many NATO militaries used bullets made of wood and plastic because for the type of training and distance they were doing (familiarization under 100m) the difference was more or less negligible. Most rifle projectiles

So I guess I don't have a SPECIFIC answer. If you're looking to make several rifles with optics and projectiles calibrated to impact similarly at a single specific range, you can basically do this by zeroing all the guns' optics at that distance; problem solved. The problem though is they will only match at that specific distance, because the other factors don't match.

As stated they are all at 1050 fps, only difference is weight and bc. I'm just looking for the real world drop.