13 November 2023

Practical Velocity - What Velocity Do You Actually Need and How Does Barrel Length Apply?

 I don't know if the phrase Practical Velocity exists in the world of firearms but it should. I've heard of practical accuracy but I've never heard practical velocity but I think it's a concept that we should talk about. The idea is pretty straight forward. I would like to start with a question. Do I need the absolute ragged edge of velocity I can get? No. I need to push my bullet to a velocity that works for what I am doing. 

In combination with barrel length, what velocity does your cartridge push the bullet when it exits your gun's barrel and what is the furthest that bullet is effective? I like to quantify effective as the bullet expands reliably as hollow points and soft points will lose enough velocity at some distance and won't expand. Past that point, they are about as useful as an FMJ. So from the hunting perspective, what is the distance I could hunt a deer and get reliable expansion on my JSP? From the self defense perspective, what is the distance your HP bullet will expand. If you land a hit on a mass shooter, will that bullet still be effective?  Let's dive in.

Distance is relative in this discussion as bullets are dependent on velocity to expand. Different bullets and different calibers need different velocities. A 9mm Speer Gold Dot hollow point bullet might only work correctly from 1050 fps to 1450 fps at the muzzle. A Remington 158 gr SJHP might work from between 1100 fps to 1800 fps at the muzzle. Depending on the velocity you get from your firearm, you can look at the bullet's velocity window and see about how far your bullet will likely still be effective. Your 9mm carry pistol pops that bullet at 1200 fps from the muzzle. That velocity might only be good for 45 yards with the bullet moving at 1050 fps at that point but if you switched to a longer barrel, now you get 50 yards. If you switched to a 16 inch barrel rifle and get 1450 fps, you might get 100 yards by the time the bullet drops to 1050 fps. Does it matter? Are you carrying that rifle everywhere you go? Are you taking defensive shots at 100 yards? Sometimes, maximum velocity isn't needed or practical. I've heard the FBI say most engagements happen at 7 yards. I don't know if that's true but your little carry gun covers that nicely. No need for the PCC with a 16 inch barrel on your day to day. Then again, the world is a little more scary these days. Maybe take a packable 5.56 rifle with you. 

If you need more velocity, switch to a longer barrel. If you don't need the extra velocity you could reduce barrel length to make the gun more handy or your powder charge and reduce recoil. Maybe even move to a smaller cartridge. 

Let me give you an example.

My Marlin 1894 with a 16 inch barrel chronographed around 1800 fps. I suspect that the bullet is still good to expand as low as 1100 fps. With a ballistic coefficient of 0.145 per Remington, the factory ammunition should still be effective to around 190 yards from my rifle. That ballistic calculator says the drop with a 100 yard zero is around 14.6 inches but hits the 3 inch mark around 130 yards. If you tinker with zeroing, I would argue that 1800 fps is more than enough to make the .357 Magnum Marlin a 150 yard rifle with the perfect zero. If I only ever hunt with distances of 100 yards and less, then why have enough velocity for 190 yards or fuss with setting up the rifle for 150 yards with a weird zero. Well, there are a few reasons to keep what I have and a few reasons we could make changes. I could shorten the barrel from 16 inches to say 14 inches making the rifle a little more handy and maneuverable. I could keep the barrel length I have and enjoy the flatter trajectory.

If I have a reduced velocity of 1600 fps from a shorter barrel, the velocity still covers my needs for a 100 yard hunting rifle. The ballistic calculator says that a 100 yard zero at that velocity gets me out to 125 yards with no problems. I'm happy to take that shorter barrel. 

Sticking with the .357 Magnum theme, I calculated that if all I ever hunted was under 75 yards from a deer stand, I found that my 4 inch barrel revolver could almost cover that at around 1240 fps. If I have a 6 inch barrel, the bump in velocity should just be enough to get me past the 75 yards. Why carry an 8 pound rifle which I can carry a much lighter revolver? A Thompson Center Contender could play that same game nicely. 

The AR-15 could be another great example. Let's take a look at that platform.

Many people who hunt deer with an AR-15 have used longer barrels in the 20 and 24 inch length for around 3200 fps with a 55 gr JSP. If your deer stand or blind only gives you a sub 150 yards and if the 24 inch barrel can easily get you to 250 yards, then trim that barrel down to say 18 inches or 16 inches and save some weight and length. If you changed ammo to something that doesn't require higher velocity, such as a solid copper hollow point, then we could trim that down even more. A 16 inch or 14.5 inch would make for a good woods rifle if the ammunition can work in your situation. Know where you're hunting and what you're hunting with.

I've been looking over the Barnes VOR-TX 62 grain factory load for a while. Some people have had success out to 200 yards with those TSX bullets. I have a 14.5 inch barrel pin-and-weld rifle as my Primary Rifle and while I don't think I have the velocity for 200 yards, the numbers I recorded with my chronograph might put me easily to 150 yards and still expand nicely. It might actually go further. More data is needed. Simply, why have the longer and heavier rifle if I don't need it?

What if I do need the higher velocity? What if I'm out West hunting elk at ranges such as 500 yards? Well, then you will likely need that longer barrel and a bigger powder charge. There is a reason that cartridges such as 7mm Remington Magnum exist. Higher velocity can also give you a longer distance MPBR or maximum point blank range which helps with unknown distance hunting. Package out your rifle and ammunition to get that bullet to the target. 

In the above examples, the rifles have differing ammunition choices and barrel lengths. The velocities are wildly different and the bullet construction is different. By understanding the ammunition, we can package out rifles and pistols that are tailored to our needs. Do you need the 24 inch barrel in .270 Winchester? Can we run a 20 inch barrel instead? If you've been hunting with a .300 Winchester Magnum with a 26 inch barrel, can you change calibers and choose a shorter barrel to something like a 18 inch barrel .308 Win?  Can you reduce your powder charge and save a few grains if you handload?Your shoulder and pocket book might thank you later.

I don't know if I have articulated my idea of Practical Velocity to you. If not, hit up the comments section below. 

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