What is your opinion of a 37 grain bullet for the 204 Ruger?

[Bayou City Boy]

BCB - lol (on the writer's cramp)


It would be too much typing to provide the info....


I will let it be..........

Maybe just write down the mathematical formula. It can't be that long.... ....And any technical issue involving variables can be mathematically shown.... Or maybe an internet link.....?

Or better yet, come down to south Texas and I'll help you swage some 38 grain 20 caliber bullets with a jacket that is too long for the bullets to stabilize in a 12" twist 204 Ruger rifle - yours or mine. It's not a hard thing to do - I've done it. They'll be just a tad longer (a few thousands of an inch) than a 40 grain V-Max.

And then we'll shorten up the length of the bullet jacket and I'll let you build some 38 grain HP 20 caliber bullets (notice same weight) that will be very accurate in yours or my 204 Ruger rifles. We'll even fill up that same length bullet jacket with lead to the bullet jacket tip and find that they weigh about 42 grains and that they too shoot very well in a 12" twist 20 caliber barrel. (I've done that, too). We can even put a lead tip on the bullet which makes the entire bullet even a little bit longer and heavier (about 43.5 grains) and it too will stabilize in a 12'"twist barrel.

We'll even use the same bullet jacket length and let you build some 28-37 grain bullets and shoot them in our 12" twist barrels also so you can see that even though the length of the lead core changed significantly in relation to the jacket length, these bullets all were stabilized in a 12" twist barrel too.

And then we'll sit under a shade tree with a six pack of Shiner Bocks and you can 'splain to me how bullet weight affected which bullets would stabilize in a 12" twist barrel and which wouldn't. Let me know before hand so I can get the Shiner Bock on ice. It stays warm all year 'round down here...

-BCB

[Glen]

Could the difference of opinion be stemming from the fact that the bullet weight is printed on the boxes & not the bullet length?? Then add the fact that when folks ask " I have a 1/xx twist in my heavy barrel varminter so what would the appropriate bullet weight be for this rig?"

Just wondering out loud.

[Hotshot]

Thought we might have to take you boys out to the woodshed to settle this, but BCB's idea involving ice sounds like a great solution. Maybe you can agree to disagree untill then.

[Bayou City Boy]

Could the difference of opinion be stemming from the fact that the bullet weight is printed on the boxes & not the bullet length?? Then add the fact that when folks ask " I have a 1/xx twist in my heavy barrel varminter so what would the appropriate bullet weight be for this rig?"

Just wondering out loud.

[

Glen:

What you said is what I tried to say in my response to Rick. We as consumers are used to thinking of bullets in terms of bullet weight so the bullet makers bypass the math for us and equate weight to barrel twist to make things simpler for us.

In reality however, the math (formulas for barrel twist) clearly shows that bullet length and velocity are the two variables for choosing the correct bullet in any caliber for a certain barrel twist..... Bullet weight is not involved in the math at all.

Sorry if sticking to my guns offended anyone. I come from a technical/engineering background and in that realm all problems/issues involving variables can be solved mathematically. If there isn't a formula to solve an issue, any "solution" is just an incorrect guess or possibly folklore not based on factual data. In this case the common way to refer to bullets (by weight) just happens to lead some folks to believe that barrel twist is weight dependent when the math shows that is clearly not the mathematical, scientific, or physical (Physics) reality.

-BCB

[WrzWaldo]

In reality however, the math (formulas for barrel twist) clearly shows that bullet length and velocity are the two variables for choosing the correct bullet in any caliber for a certain barrel twist..... Bullet weight is not involved in the math at all.

Bingo! That's it in a nutshell folks.

[Glen]

OK. Just wondering.

[Grayfox]

BCB

Thanks for all the bullet forming information.

From your testing and knowledge of bullet makeing, could you explaine to us the perfect 38 gr bullet you would make to sell if you were a bullet company? What BC would it have? What demensions for lenght and bearing surface?

Please do not think I'm trying to put you on the hotseat. I'm only asking because you have been there and done it.

Grayfox

[Grayfox]

A couple months ago I called and talked to Hornady, Sierra, and Nosler about bringing out a 37 grain bullet. One of the interesting things we talked about was bullet stability. One of them told me to file about three grains off the bullet tip. An example is to make a 40 grain bullet weigh 37 grains after fileing the tip back. Then fire the rounds and see if accuracy improved. If you had an improvement then the bullets had stabilized better and matched your rifle twist better. Doing this only changes bullet lenght and weight. All other bullet dimensions stay the same.This changes the bullets the center of gravity and it's stability.

I was not able to try this because Wisconsin is very cold this time of year. When it warms up in March I will do some testing of the 40 V Max and 40 BT.

Grayfox

[acloco]

Could the difference of opinion be stemming from the fact that the bullet weight is printed on the boxes & not the bullet length?? Then add the fact that when folks ask " I have a 1/xx twist in my heavy barrel varminter so what would the appropriate bullet weight be for this rig?"

Just wondering out loud.

[

Glen:

What you said is what I tried to say in my response to Rick. We as consumers are used to thinking of bullets in terms of bullet weight so the bullet makers bypass the math for us and equate weight to barrel twist to make things simpler for us.

In reality however, the math (formulas for barrel twist) clearly shows that bullet length and velocity are the two variables for choosing the correct bullet in any caliber for a certain barrel twist..... Bullet weight is not involved in the math at all.

Sorry if sticking to my guns offended anyone. I come from a technical/engineering background and in that realm all problems/issues involving variables can be solved mathematically. If there isn't a formula to solve an issue, any "solution" is just an incorrect guess or possibly folklore not based on factual data. In this case the common way to refer to bullets (by weight) just happens to lead some folks to believe that barrel twist is weight dependent when the math shows that is clearly not the mathematical, scientific, or physical (Physics) reality.

-BCB

BCB - I AM an engineer.....

Believe I stated what you were arguing about many posts ago.....and just let it go. I should not have.

My post:

"Bullet weight is the indicator, because if you increase the bullet weight, the piece of lead that you cut off will be longer for a 40 gr bullet than a 32 gr....but all stuff neatly in the same jacket.

The "bearing surface length" should be the indicator of what twist rate is needed."

Yes....if you have the swaging equipment, you can create a bullet that is long in length and light in weight. The obverse is true as well.

[Bayou City Boy]

acloco:

Let's just agree on this; We obviously didn't graduate from the same College of Engineering.

I'm not an "AM" like you....I'm a "WAS" - I retired @ 4 years ago... But I feel pretty confident that the Laws of Physics and Dynamics - and the pertinent math - haven't changed since I was an "AM". I'm gonna stick with those things. And you of course can choose to believe whatever you want to believe.

Isn't America a great place.....?

PS: The offer on the Shiner Bock still stands....

-BCB

[acloco]

LOL!....we are actually agreeing on the theory...really.

Length of the bullet is what determines the twist rate needed.


Correct???

[Grayfox]

I went and measured the bullet lenght and bearing surface lenght of the Sierra 39gr Blitzking, Hornady 40gr V-max, and the Nosler 40gr Ballistic Tip.

Sierra 39gr: lenght .736" bearing surface .250"

Nosler 40gr: lenght .743" bearing surface .310"

Hornady 40gr: lenght .748" bearing surface .258"

Sierra has the shortest boattail.
Nosler's boattail is a little longer than the Sierra's.
Hornady's boattail is twice as long as Noslers.

Wayne Blackwells "Load from a Disk" computed a 37gr boattail bullet lenght of .665".
The bearing surfaces of the 32gr Sierra, the 32gr Hornady, and the 34gr dogtown bullets fall between .245"-.250". The 37gr with a small boattail and a bearing surface of .250" and .667" lenght should be ideal weight to stabilize in the 1-12" twist.

acloco, as an Engineer what is your opinion as to the ideal weight?

Thanks, Grayfox

[Glen]

How can a 37gr bullet kill my groundhogs any better than the 39gr BK load I'm using now?? All I'm asking is that if the 37gr bullet won't group in MY rifle as well as the 39's do then what would be the ideal bullet weight in the 204?? Just curious.

[Bayou City Boy]

Glen:

Your post is right on. There is no "ideal" bullet for any caliber. Maybe a more popular one, but not an ideal one. Much like the 130 grain bullet seems to be the more popular choice for a .270 Winchester for a lot of reasons... that's why I didn't try to answer a hypothetical question when Grayfox posed it...

Grayfox:

To answer your quote: "The 37gr with a small boattail and a bearing surface of .250" and .667" lenght should be ideal weight to stabilize in the 1-12" twist."

More correctly.... the 0.667" length would make any reasonable weight of bullet - that is well designed - stabilize well in a 12" twist barrel.

By using the term "well designed", I'm saying that the center of gravity of the bullet is in the proper place and the bullet itself is balanced so it will be aerodynamically stable in flight. If the bullet is not well designed, it won't be stable in flight after traveling through any rifle barrel no matter what the twist rate might be.

Any guesses as to why a 39 grain Sierra will stabilize in a 12" twist barrel and a 40 grain V-Max won't in the same barrel? Simply because its slightly shorter and the lengths of the factory 39-40 grain bullets are all on the marginal end (maximum length) for a 12" twist rifle.

Again....bullet bearing surface and weight has nothing to do with which bullet will stabilize in a 12" twist barrel and which one won't. Length is the only physical bullet characteristic that is important.

aclolo:

I was not debating a theory with anyone,. I was presenting a known fact:

T = Twist rate in 1 turn per inches.
L = Bullet length in inches.
V = Muzzle Velocity
D = Diameter of the bore grooves in inches.
Constant = 3.5

Find the optimum twist rate from velocity, bore size and bullet length:

T= ( 3.5 * SqRt( V ) * D² ) ÷ L

Again.....Notice there is no mention of bullet weight or bearing surface or any other things in the mathematical formula.... Also, if there is a mathematical formula to solve an issue as simple as this, its a known fact and not a theory.

I hope everyone has a Great Holiday Season...

-BCB

[Grayfox]

BCB

You have been very helpfull. Thanks for your input.

Glen

My idea of an ideal bullet in the 204 is this:
High BC for long shots.
Heavy enough to do the job on what I shoot with it.
It must be very accurate with many different powders.
Reasonable priced and avaliable to buy when I need them.

Right now I have only one bullet and load combination that will shoot very well out of all three of our rifles. That is the Sierra 39BK, Rel 10X Powder, GM 205 M Primers, and WW Brass. My options are very limited with the 39gr Sierra bullet.

A 37gr bullet should give us alot more choices of powders and other components. This means more fun at the reloading bench and rifle range. Nor should I forget to mention the 1000's of bullets needed to shoot PD's each year.

Grayfox