Why do we 'need' speed?

[JamieC]

I was out at the range today testing some new loads, brought the chronograph with me. I had some loads, (.223 AR, 1:9 twist, 16" barrel), the first was Win 748, 24.8 gr, Everglades Ammo, 55gr fmj. They had been pretty accurate out of some of the different amounts of 748 powder, (yeah, I know 55gr fmj ain't the best for accuracy), anyway, the chronograph said 2674fps average. I had just bought some TAC, heard good things about it, finally found some. Using the same 55gr bullets, 24.3gr of TAC averaged 2657fps, 24.9gr averaged 2763fps, 25.5gr averaged 2806fps. I had some PPU, (Privi Partisan), 55gr fmj, they averaged 3043fps. One of my best groups was the starting load of TAC, 24.3gr. Question, when is speed important? If my accuracy is good, the gun cycles, why would I go for more speed? I plan on testing some more using the TAC, from what I've read, the Ramshot loads are very conservative. If my most accurate load is the slowest, should I use that for range work? Kinda seems like I answered my own question. Now if SD is part of the equation, NOW how does speed factor in? If I'm loading soft point ammo, hollow point ammo, do you go for more speed for better 'knock down', better long range accuracy? I tried some 75gr BTHP bullets, real accurate, right around 2500fps, seems slow to me. I know it's a gun thing, car thing, etc., more speed is better...or is it?

 

[splattergun]

Velocity is part of the terminal energy formula, along with mass. Higher velocity, greater terminal energy. In the .223, the speed is important because there is such a light projectile. Speed is what makes the .223 deadly.

If accuracy, not terminal energy, is your goal, then stick with your most accurate velocity.

 

[higgite]

Besides what splattergun pointed out, the slower the bullet is, the longer the wind has to push it off course.

 

[Sam1911]

To some degree, it isn't. You've got "X" cartridge and that cartridge develops approximately "Y" velocity (+/- 150 fps or so) with bullets of weigh "Z." Squeezing 20 or 30 or 50 or even 100 fps more out of it is a bit of a juvenile* quest, if the load is accurate and the bullet will do what you want it to do at the ranges you'll ask it to do that thing.

Now, if you're afraid you might be on the edge of cycling reliability because the charge is low, that would be a fine reason to try and find another, higher, velocity/pressure node that produces good accuracy. Then when the gun is dirty and sluggish, that extra oomph might keep things ticking a little longer.

If you're afraid that at the distances you shoot the bullet might not behave properly because ballistic charts tell you it will have dropped below the bullet maker's lower threshold for expansion, that would be a very important reason to push on and find a higher velocity load.

And something you should ask yourself is what does "most accurate" mean to you, and why? Accuracy is always a primary goal in creating handloads, but does accuracy for the sake of a tighter group become "THE" goal? What do you need this rifle to do? Shoot 12" steel gongs at 300 yds? Shoot big 3-gun practical targets on the move at distances from 3-50 yds? Shoot prairie dogs at unknown distances out past 500 yds? Shoot the CMP "highpower" match course with the Masters?

The very best accuracy you can get MIGHT be the right thing to go with. Or it might be just as much a self-serving exercise in tail-chasing as the velocity quest can be.







* - By "juvenile" I simply mean that it isn't a very educated, enlightened, goal, but rather a brutish largely futile one. Seeking a bigger number for the sake of the simplistic thinking that more is better than less: number chasing, machismo, bragging rights, etc.

 

[JamieC]

Sam1911, well put!

 

[jmorris]

We don't always need more speed, if you want more energy just use more mass and a better trajectory doesn't automatically equal more accuracy.

 

[choppinlow]

Who cares about speed or velocity or energy if you can't hit the target consistently or you beat your shoulder to death? Not to detract from your question, but I think accuracy is first then consider the others.

It is like the old racer mindset: I don't care how fast you can go, if you don't cross the finish line you will never be the winner.

 

[JimKirk]

If you want to say.... hunt elk .... do you pickup a sling shot shooting a 500 gr ball bearing at maybe 100 fps or do you pickup the the .30/06 that slings a 180 gr bullet at 2900 fps...

I know that is a drastic comparison ... but it also shows the need for speed ... but you also don't need a .30/378 Wby to kill an Elk either...

Speed is important, but so is accuracy ... that is my goal with my reloading ... get as much speed as I can safely and also be accurate as well ... sometimes the two don't meet and you have to pick the most important to you....

 

[ColoradoShooter77]

My goal with 5.56 was to match the velocity of factory XM-193 ammo from a 16" barrel. The 193 rounds chorno'd right at 3000 fps.

My 55 grain FMJ loads with 26 grain AA-2460, magnum primer and L-C case....chrono'd right at 3000 fps.

I do all of my shooting off-hand at 50 yards with my AR.....I don't think I'll notice a huge accuracy difference with different loads. They all print about 4" groups at 50 yards.

 

[Rule3]

"Speed kills"

Comparing regular 223 loads to service loads.

Bullet kinetic energy which does not have diddly to do with accuracy.

http://www.shooterscalculator.com/bullet-kinetic-energy.php

If you "had" to be shot with a 40 grain bullet would you rather be hit with a 22lr or a 223/556?

 

[jmorris]

If you had to be shot by a bullet going 3000 fps would you want it to be a 40gn or 650gn?

 

[JamieC]

If we compare "regular 223 loads to service loads", an XM-193 is loaded to achieve approx 3,000fps, why? Is that the most accurate speed for that load? Was 3,000fps specified for knock down power? Was that speed needed to kill out to a specific range? Most factory ammo, 55gr fmj, seems to be loaded to achieve 3,000fps. If I'm just looking for the most accurate ammo to shoot at the range, speed doesn't matter. If I use less powder, I can load more. Thinking SD, when the war comes, the zombie apocalypse, etc., my neighbor across the street, their front door is about 45 yards from mine, neighbors on either side of that house, about 75 yards to their front door, two houses down, either way, about 100 yards. My point, in my neighbor hood, I don't much need to be able to shoot beyond 200 yards. That's as far as the range I normally go has. If I find a reason to shoot to kill 200 yards and beyond, THEN maybe speed becomes a bigger factor, right?

 

[Rule3]

If the "threat" is 200 yards away you do not need to be shooting at it

A 2000 fps or a 3000 fps bullet is still going to do it's job. The Service loads are just that for full power Scotty.

Load the most accurate for your rifle whatever the FPS may be.

 

[buck460XVR]

Now if SD is part of the equation, NOW how does speed factor in?

It only factors in when it comes to terminal performance. For SD, one does not have to worry about wind deflection, ballistics and the bullet losing velocity downrange. If the muzzle velocity is in the parameters of what the bullet itself is designed for, then accuracy and reliability are the primary concerns. There is a myriad of expectations from ammo and most of them are relative to usage. Punching holes in paper @ 1000 yards is much different than trying to drop a 250# BG at 3 feet.

 

[jmorris]

Thinking SD, when the war comes, the zombie apocalypse,

No need to chronograph video games.

 

[blarby]

The largest "speed" factor for me is bullet terminal performance.

This varies tremendously on the rifle and it's purpose, of course.

With a .223 FMJ, a hole is a hole, at some point...

With a 30 caliber Hornady Interbond, for example, 300fps difference at 450 yards is a tremendous difference in bullet deployment on target.

Matching your bullet, impact velocity at expected ranges of engagement, game type, AND shot placement are all significant factors in hunting load development. Ignoring one for another is a significant handicap in the field, and can lead to some interesting carcass finding around the witching hour ! Ever watched a muley literally jump off a cliff after a 150 yards Sprint just as it's getting dark ??? A worst case scenario, for certain, but bullet effect cannot be discounted for accuracy. You need all the factors for a clean kill, or to hedge against subpar "buck fever" shooting.

In the case of AR'S, speed is one thing...gas volume for CORRECT cycling is another. While they are connected, one does not necessarily drive the other.

Chasing a unicorn speed result at the expense of a weapons' reliability and longevity because of overgassing is not an uncommon failing of the platform for handloaders, but it is a totally preventable one.

 

[spitballer]

when is speed important? If my accuracy is good, the gun cycles, why would I...

Just speaking as a bolt man it seems to me that an autoloader is complicated in the same way that modern automotive systems are complicated. Firearms are designed differently for different uses, and an AR15/M16 is designed to get a lot of bullets downrange fast with a minimum of fuss. If it can bust a steel pot at 500 yards it doesn't matter how much velocity it has. It is a remarkably accurate platform for it's size and personally I was glad to have the M16 and not the AK47 when I was in the service. But my suspicion is that, like a modern car, when you fool with one specification (like chamber pressure or rate of fouling) it affects the entire system. Therefore I would be inclined to use ammo that's as close to mil-spec as possible because the military has already done the hard work insofar as optimizing the ammo for that rifle. I'm not a rocket scientist like some of the other guys on this site but yes, I think higher velocity may limit exposure to crosswinds for certain types of shooting but I'll take accuracy over velocity any day for any given rifle

 

[jmr40]

Speed at the muzzle isn't nearly as important as speed at impact. The 55 gr bullets will start faster, but the much better aerodynamics of the 75 gr bullet means it will be almost as fast at 100 yards in addition to being 20 gr heavier. By the time you get 500 yards the 75 gr bullet is almost 400 fps faster than the 55 gr bullet even though it left the barrel 250 fps slower.

Using your chronograph numbers and looking up BC's for Hornady 55 gr and 75 gr bullets I got the following numbers.

55 gr .243 BC

Muzzle-2750 fps
100 yards-2388
200-2054
300-1750
400-1482
500-1260

75 gr .435 BC

Muzzle-2500 fps
100-2305
200-2119
300-1942
400-1774
500-1618

Even with the fastest load you tested, 55 gr @ 3043 the 75 gr bullet will be faster at 300 yards, about 200 fps faster at 500 yards. And this with a 20 gr heavier bullet.

Muzzle 3050
100-2663
200-2309
300-1982
400-1685
500-1420

 

[JamieC]

Hmmm, hadn't given the BC differences in bullet weights much thought. Good stuff, thank you, thanks to all, I got a lot of good info from this thread!

 

[ColoradoShooter77]

The reason I load 55's are because they are dirt cheap, like 8 cents/round. I could shoot 69 grain HP's with my 1:9 twist AR, but they are around 20 cents/peice. For punching paper at 100 yards....not worth it.

 

[345 DeSoto]

"If the "threat" is 200 yards away you do not need to be shooting at it."

What HE said^^^^^^^

 

[Arkansas Paul]

For SD situations, it doesn't IMO.
If it will cycle your gun, its enough.

Even for hunting, I don't give a rat's derrier about it. I don't own a chronograph and have no plans to buy one. I load within the manual's specifications and I've never yet had a deer look at me and walk away.

 

[DocUSMCRetired]

As others have hit on, speed is not everything.

A higher BC bullet, moving a little slower, will in fact have better performance down range. While you might have more upfront speed, the lower BC bullet will lose velocity, and energy at a faster rate.

So sometimes it is more advantageous to run a better BC bullet at a lower velocity. Another thing to consider is transonic stability at long range. For instance the Berger 185 Juggernaut which got its nick name for its transonic stability. You could try to push a 168 grain bullet out faster so it stay super sonic longer, or you could use a bullet that is transonic stable and not worry about it.

 

[mdi]

I've read through most of the posts and I don't agree with many about a "need for speed". Perhaps it's in the same mode of thinking to "need" a 350-400 horse power engine that will power a car to 150 MPH (when most speed limits are waaaaay below that). I have always figgered if my 30-06 ain't powerful enough I'll go with a 300 Win. Mag. rather than load up the '06 (same with my handguns, if 357 is too light, I'll go with my .44 Mag.).

Jes an old guys thoughts...

 

[cougar1717]

My deer is definitely deader with that extra 200 fps

But really...
It's about matching velocity, bullet construction, accuracy, and cycling (for semi-autos).

For 223 varmint bullets, extra velocity helps them shatter on impact, however, that wouldn't be a concern for FMJBT's.
Guys who push .308 diameter accubond bullets to 3400+fps with magnums can have them shatter on an elk. It's not that it isn't a good bullet, just outside its' usable expansion range.

Loads aren't useful if they aren't reasonably accurate or they don't cycle your rifle.

IMHO velocity is important, but only to a certain extent. To put them in order, I would first want cycling, then accuracy, then bullet expansion/velocity. If it was too slow to reliably expand, then I would give up some accuracy for terminal performance.