I know twist rate but, what about velocity?

[IAM Rand]

Okay, so here is my dilemma, reloading some 223 Remington. I have looked up twist rate for bullet weight. What about velocity. I think I may already know the answer but, thought I would throw it out here.

I am sure that it will have to be one of those things where I just try out different velocities to see what works best in my carbine but thought that it might be nice if there were some formula where you could punch in barrel length, bullet weight, twist, and velocity and Volia', you have the most accurate load.

I know, I am probably dreaming but, hey, a guy can dream can't he!?!?!

 

[oldman10mm]

Yes, you are dreaming !
223 in what firearm and what is its' twist rate ?
Powder burn rate ( fast, medium, slow), type of powder (ball or extruded), bullet seating depth (close to lands and far from lands), barrel harmonics/vibration all contribute to good load/bad load.

Remington and Federal both make match grade 223 ammo, with Federal seemingly have the best results in a variety of rifles.

 

[DWalt]

Okay, so here is my dilemma, reloading some 223 Remington. I have looked up twist rate for bullet weight. What about velocity. I think I may already know the answer but, thought I would throw it out here.

I am sure that it will have to be one of those things where I just try out different velocities to see what works best in my carbine but thought that it might be nice if there were some formula where you could punch in barrel length, bullet weight, twist, and velocity and Volia', you have the most accurate load.

I know, I am probably dreaming but, hey, a guy can dream can't he!?!?!

There is a twist rate stability equation, but bullet stability does not necessarily correlate closely with grouping performance (accuracy is a somewhat different concept).

 

[Nevada Ed]

Some bullets will take a high fps;

while some will come apart, due to their make up.

Match the speed to the bullet, being used, for best results and accuracy.

 

[Ivan the Butcher]

Think of a matched set: Bullet Weight, Bullet Velocity and Refiling.

Heavier bullets can only go so fast safely, and they use a faster twist rate to stabilize. You can push the boundaries to a small degree. If you are using a detachable magazine, you are locked into a maximum cartridge length. You are still locked into a maximum length by other factors too, But seating bullets over maximum "Factory" length allows more sspace to put more powder in safely, and that lets you fudge the velocity up a little bit.

The whole of the ratio between Weight/Velocity/Twist is you end up at the "Golden RPM" of spinning bullet. The PhD Ballistic gurus claim this RPM is around 140,000 to 150,000 RPM.

Example: I have a very good bolt gun with a 1:9 twist in 223. Standard length won't allow enough powder to get sufficient velocity with a 75 grain bullet. But I can seat the bullet out enough to over stuff Varget in the case that I can get velocity and good groups at 1000 yards. I can't use this load in the other three 223 rifles I own. So I never try shooting them at 1000 Yards.

Ivan

 

[DWalt]

This is probably the most comprehensive source for external ballistics calculations available anywhere. Even the ammunition manufacturers and the U.S. military use it. It also contains a bullet gyroscopic stability calculator. JBM - Calculations

 

[Skeet 028]

I've always understood that the longer and heavier a bullet the faster it must spin as velocity will be less with the heavier bullet in the same caliber. I know there are ways around it...more powder etc etc seating depth blah blah blah...I know there will be exceptions. But for the most part isn't that true?? I have a M-4 clone that will shoot 55 gr bullets ok...but the Bushmaster Varminter has a 9 inch twist and shoots most weights well as opposed to the 7 inch twist. The 9inch even shoots the 40 gr plastic tipped bullets pretty good. The 7 inch starts to gain accuracy with the mid 60 gr bullets and up

 

[rwsmith]

All I know is that.....

...heavier bullets for the caliber are usually the most accurate and it takes a higher twist rate to stabilize heavier bullets (Plus some length of barrel. I have no experience with short barrels in .223). That's why I stick with >/= 55 grain out of my 1:7" barrels. Sometimes I load 65 grain projectiles. The match grade that most ammo brands put out have 69 to 77 grain projectiles. I'd be comfortable that my 16" 1:7" twist barrels would stablize the heavier bullets, but I hardly ever shoot far enough to make a difference so I can't say for sure. I can say that I get good round .22 sized holes with no ovals or keyholing.