Gentlemen:
After quite a few years trying to find a pre 64 Winchester in 264 Win Mag, I finally found one. I was wondering if any of you have loaded Reloader 25 in the 264 with both a 120 and 140 gn bullet. I looked in Alliant's Loading Manual and no loads are listed for RL-25. it seems that RL-25 would be a "natural" for the 264 as with most of the older powders it was considered "overbore".
Thanks,
HOOT

John Barness did an article in Handloader on the 264 a little while ago.My conclusions from my handloading odessey,match his:Ramshot Magnum and Accurate Mag-pro.Find that magazine article and read it.

Rl-25 did not work for me,each shot in the string of three increased it's velocity.Likely from chamber heat.

Try a search at 24Hr,the 264 club meets there.

quote:

Originally posted by downwindtracker2:
John Barness did an article in Handloader on the 264 a little while ago.My conclusions from my handloading odessey,match his:Ramshot Magnum and Accurate Mag-pro.Find that magazine article and read it.

Rl-25 did not work for me,each shot in the string of three increased it's velocity.Likely from chamber heat.

Try a search at 24Hr,the 264 club meets there.

Thanks for your reply. I will try to find the Handloader Magazine. What or where is the 24hr? I am sorry, I've never heard of it.

Thanks again,
HOOT

140's:
RL-25 From 60.5 grains to 64.0 grains
Winchester WLR Primer

120's:
RL-25 is too slow...

My favorite load:
Bullet: 140 Grain Sierra HPBT
Powder: 73.0 grains of Hodgdon H-870
Primer: Winchester WLR
Case: Winchester
Firearm: Winchester Model 70
Optics: Leupold 3x9
Velocity: 3132 FPS @ 15' from muzzle
Accuracy: 5-shot, 200-yard, 1/2" to 3/4"

Although I haven't tried it, the information I've seen indicates that RL 25 is not slow enough for optimum performance in the .264 with 140 grain bullets.

H-870 (no longer available) was an excellent powder for the .264, as should be the presumably very similar AA8700. I now use surplus WC-872, which is significantly slower than H-870 (at least in the lot I have). A virtually full case (weight not specified due to the great variation in the amount of powder different rifles may safely digest) of this powder gives me velocities of 3150 fps with a Nosler Partition from 24 inch barrel.

If you try WC-872, start with H-870 loads and work up from there, but only do so if you have some experience at this process and have access to a chronograph to assist in verifying what you're doing.

I don't know much about some of the newer "extra-slow" burning powders like mentioned above, but I can advise that powders like 4831, IMR 7828, RL-22 and 25, are NOT slow enough for optimum .264 velocities unless you are dropping down to 120 grain and lighter bullets.

In your 26 inch M70 barrel (please tell me yours is not the 22" featherweight!) you should be able to meet or exceed the original advertized velocity of 3200 fps for a 140 grain bullet with the right slow powder. Incidentally, I chronographed some WW 140 factory loads (yellow box) in both a 24 and 26 inch barrel and got readings of 2800 fps and under.

RL 25 works nicely for me with the 100 gr and 120 gr ballistic tips . An easy 3600 and 3400 fps respectively , out of a 24 inch barrel .

You might consider trying Retumbo and H50BMG (and similar 50BMG powders).

quote:

RL 25 is not slow enough for optimum performance in the .264

RL-25 and H-870 (as well as AR-2214) have similar burning charasteristics.

quote:

Originally posted by ricciardelli:


RL-25 and H-870 (as well as AR-2214) have similar burning charasteristics.

You obviously speak theoretically, and not from experience.

In an earlier post you list a recommendation of 60.5 to 64 grains of RL-25 with a 140 grain bullet. A quick glance at any reference that lists H-870 will show you that recommendations run as much as 10 grains more than this. My old standard load with a Speer 140 using H-870 was 72 grains, and was not a "primer pocket blower". Powders that are 10 grains (in this case about 15% difference) hardly "have similar burning characteristics".

I'm in my 40th year of working with various .264's, 34 of those years with the benefit of a chronograph. I have used everything from (fastest) surplus 4831 to (slowest) WC-860 and WC-872. In-between powders I've used would include H-570, Norma 205 (two different lots, fast and slow), and H-5010. While I have never had occasion to use RL-25, fine powder though it may be, in anything, I am certain that a powder that maxes out at 64 grains in a case that has a powder capacity of around 80 grains is a powder that is TOO FAST for optimum velocities. My experience with powders close to RL-25's (apparent) burning range indicate that it would do quite well with anything under 120 grains in a .264. Sdgunslinger's comments seem to support that supposition.

Steve: on your own website you for the 140 gr in 264 you list

RL25 60.5 to 64 gr

H870 65.2 to 78.3 gr

doesn't sound like similar burning charactoristics to me....

I would be careful of MagPro in hot weather.

Yup...you guys are correct, I have absolutely NO experience!

The case capacity of the .264 Winchester Magnum is 82 grains of water.

You can fit 73.3 grains of H-870 in that area, or 69.8 grains of RL-25. This is without compression.

Now, although someone has a ton of years loading for a particular bullet diameter, but admittedly no experience whatsoever with the powder being discussed...well, what the hell can I say.

But what the hell do I know? As I have been told, I have no experience...unless you take into consideration that I have been reloading for the .264 since 1968...

The article in HANDLOADERS Mag. was in NOV/DEC 1975 by Bob Hagel.He listed 140 Gr. Nosler 78.0 gr H-870 at 3139 ft/sec.
I have loaded for 264.sinc 1971 but mostly with 100 gr. Sierra 68.5 gr.H-4831.for varmints. These loads were with the old surplus powder.Marlin

Try some of these:

169. N170 (Vihtavuori)
170. 24N41 (Vihtavuori)
171. 50 BMG (Hodgdon)
172. AR2218 (ADI)(Same as H50BMG)
173. 20N29 (Vihtavuori)

The article was in the Handloader # 223,Feburary-March 2005.

While others will say some of these powders work for them,the 264WM shines with a real slow lineal burning powder.IMR7828 is a well behaving powder.The long skinny 140 and the big case can lead to spikeyness.In the Hodgons manual ,H-1000 will max out below the cartridge's rated max pressure,read spike.R-25.much too heat sensistive in this cartridge.N-560 tops out well before 3200.Retumbo didn't give both the velocity and accuracy needed to make a 264 worthwhile.

Gentelemen:

Thank you for the information. I will try to find some H-870 powder. Looks like that might be a tough one to find.

No, Stonecreek, Mine is the 26 inch "Westerner"

Again, my thanks to all who replied for your help. I think I am going to have a great deal of fun with this rifle. I found the recent Handloader article and the author said that he deleted some loads because he did not want to burn out his barrel. Something to pay attention to when working up loads.

HOOT

Ahhh...no sense posting this...

RL 25 is about the only thing I'll be burning in my 264 as I am mostly interested in the lighter bullets . I have not noticed any unusual heating problems with this powder and in fact , got extremely uniform chrono readings when working up my loads .

I also have the old Hagel article , but H870 will not deliver nearly as good of speed with the 120 gr slugs in my rifle as RL25 , seems to be too slow for that weight bullet .

With 129 gr SST s , I could just reach 3200 fps with either H870 or RL25 , but it takes 9 grains more H870 to do it .

The real slow burners would take over with the 140 gr weights , I'm sure . Ramshot Magnum should make an acceptable replacement for H870 , though of course not in equal charge weights . Barsness certainly had good luck with Magnum , and hereabouts , the Ramshot powders are priced a little lower than the competition .

I have not found RL25 to work well with this bullet weight in my rifle. In my load developement work, I found it to be very "spikey".

On november 26 2001 my load testing with a 140 gr Partition gave these results:
66 gr of RL25 gave me 3090 fps.
69 gr of RL25 gave me 3045 fps for 1'st shot, 3188 fps for second shot, and 3309 fps with the third shot.

I have found H1000 to be much more predictable in this cartridge, with 140 gr bullets. It gives me very linear charge/velocity curves with low velocity deviations. H1000 gives good performance in my rifle up to about 3100 fps with 140 gr bullets.

I expect, from what I have read that Retumbo and Magnum will give good results in this application. I have not had the opportunity to try them yet.

I also use H1000 in my 264 with 140 Sierra SBT, 3100 fps avg. with great accuracy.
bigbull

quote:

RL-25 and H-870 (as well as AR-2214) have similar burning charasteristics

Steve: what does that mean?

quote:

Originally posted by olarmy:

quote:

RL-25 and H-870 (as well as AR-2214) have similar burning charasteristics

Steve: what does that mean?

olarmy:

I think he's gone away mad.

Maybe "similar burning characteristics" means "will burn in the absence of oxygen".

In the case of RL-25 and H-870, it sure as heck doesn't mean similar burning speeds.

Yep, doesn't look like he's going to answer.

BTW, what kind of terminal ballistic performance did you get from the 140gr Speer in your 264? Good penetration? Any problem with premature "blow up". Considering using them in a 264 for deer. Thanks.

I used the Speer years and years ago, and have long since switched to the Nosler Partition. However, this was for other reasons than terminal perfomance. I killed a number of whitetails with the Speer 140 and had no complaints about its terminal performance. I can't recall having used it on anything larger than whitetails and one mule deer, so I can't say how it might perform on larger game.

Hoot Murray

Case: Winchester
Primer: Federal 215

156 grains ( 10.1 gram)
Norma Oryx
C.O.L = 3.15 "/80 mm

Norma MRP
Max. 57.8, 2887 fps/ 880 m/s
Min. 55, 2759 fps/ 841 m/s


120 grains ( 7.8 gram)
Norma FMJ
C.O.L = 3.268 "/83 mm

Norma MRP
Max. 66.4 3356 fps/ 1023m/s
Min. 63 3209 fps/ 978m/s

Cheers
/JOHAN

I owned a pre 64, 264 When they first came on the market, I would have as soon had a mule kick me Oh I killed some big bucks but it was not worth the beating.I believe I paid $129 for it.I would not give you that today. It would sure shoot ,I think I killed more Bucks when I bought a 6 MM and I did not have the mule kicking. luck

My 264 still has the FN musketteer stock,a fast handling classic patern,not a Weatherby kind of stock,at all.It's easier shooting than the BDL 30-06.

In order to predict the rate of gas production from a burning propellant grain, we need to make some assumption about how the powder grain burns, both geometrically and thermodynamically. If the burning is a surface effect, the burn rate might be proportional to the number of molecules hitting the surface. This would mean it would be proportional to the pressure and temperature. The temperature of the burning is determined by the energy of combustion and the heat capacity of the products and would be constant. The burn rate could then be expressed as a rate constant relating how fast the flame front burns in a single dimension per unit pressure. A more general expression incorporates a pressure exponent parameter that need not be unity. Piobert postulated that the burning of a powder grain occurs in parallel layers from the surface to the interior. This has been shown to be a pretty good approximation by observation of partially burned grains of powder. The rate of gas production is then related to the surface area of the grain, the rate constant and pressure. The surface area may change with the burning depending on the geometry of the grain. If we designate the minimum burning dimension of the powder grain as "D" and "f" as the fraction of "D" that is left unburned, the reduction of the dimension "D" at any time is (1-f)*D. The burn rate is therefore -D*df/dt which is equal to the linear burn rate constant (beta) times the pressure (P).

-D*df/dt = beta*P (1)

The Form Function
Now the effect of the grain shape must be taken into account. The mass of gas produced will be equal to the mass of powder that has burned which would be proportional to the volume of the powder grain that has burned. If we say "z" is the mass or volume fraction of of the powder burned (or gas produced), then

z = (initial volume - vol. at time "t")/(initial volume)

Now "z" can be calculated as a function of "f" for various shapes. A tubular shape with wall thickness "D" and average radius "R", and length "L":

initial volume = 2*pi*R*D*L

at "t", the wall thickness is D-(1-f)*D = f*D

the length is L-(1-f)*D , so

vol at "t" = 2*pi*R*f*d*(L-(1-f)*D)

and

z = (1-f)(1+f*D/L)

This led to defining a general form function

z = (1-f)*(1+theta*f) (2)

where theta is the form factor and can range from -1 to +1. A form factor of 0 implies a constant area burn surface, such as with a tubular powder with a length much greater than the wall thickness. Long solid cylindrical stick powder such as cordite has a form factor of 1. Multiperforated powder actually increases in surface area with burning and has a negative form factor. Ball powder would follow the equation z = (1-f)^3 and is not easily modeled by the quadratic equation 2. Flake or disk powder has a cubic term but can be approximated by equation (2) with a theta of D/(L/2) where L is the diameter of the disk or length of the flake. The quadratic form of equation (2) allows the analytic solution of the model which would be much more difficult or impossible if we included a cubic term. There are more serious difficulties with modeling ball powders than the form function, however, such as the use of burn rate retardants.

Progressivity and Retardants
A progressive powder is one with a negative theta, that is the burning area increases with burn time. A degressive one is the opposite, like cordite or spherical powder, where the surface area decreases substantially with burn time. Retardants are additives that are diffused into the powder grain from the outer surface that reduce the initial burn rate of the powder. This is has the effect of rendering the powder more progressive, and is used especially with ball powders to make them less degressive. A progressive powder has the advantage of producing a higher average pressure to peak pressure ratio than degressive powders, thus giving higher bullet speeds for a given peak pressure. In order to model the action of the retardant it would be necessary to introduce "beta" as a function of "f" and solve the system numerically. Coppock's model cannot handle the effect of retardants except by adjusting the value of "theta" and "beta".

Analytic vs Numeric Solutions
One could point out that with the computer power available now, there is no reason to constrain our assumptions to those necessary to solve the equations analytically, and simply do them numerically with a step by step process. This is quite true, but the numeric solution has its own set of difficulties to overcome and a analytic solution is very useful in testing the convergence and accuracy of a numeric model. This analytic solution has been found to offer useful solutions and is a good starting point, so it has been presented here. It also has the advantage of being faster to compute so it can be programmed into a graphing pocket calculator, for example, which would be too slow with a numeric model.

The Equation of Motion
The equation of motion of the shot (bullet) can be written immediately:

Ps(x)*A = w*dv/dt (3)

The pressure at the base of the shot (as a function of x, the shot travel distance) times the area of the shot base would give the accelerating force which equals the mass (w) of the shot times the acceleration.

The Ideal Gas Equation
In freshman chemistry we learned the ideal gas equation:

PV=nRT

which relates pressure, temperature, volume and with the number of moles of gas "n" and the gas constant "R". The equation works best for small molecules at low pressures. Some correction is needed at the high pressures experienced in a gun, so we will add the "covolume" term (b), a simplified version of Van Der Waal's semi-empirical ideal gas corrected equation called the Alfred-Nobel equation:

P*(V-b) = nRT

If we divide both sides by the mass of the gas we get:

P*(V-b)/m = R*n/m*T

If V and b are in units of volume per unit mass of gas the equation becomes

P*(V-b) = R/mw*T

where mw is the molecular weight of the gases (mass per mole). The covolume can be thought of as a correction for the finite volume of the gas molecules.

The Force Constant
If the powder is burning at constant volume with no heat loss, the gas equation yields

P(V-b) = R/mw*T0

where T0 is the product gas temperature. The right hand side is a constant that depends on the molecular weight and the gas combustion temperature and is designated as the Force constant "F". This is also called Impetus by some powder companies.

F = R/mw*T0

and has units of energy per unit mass.

The Adiabatic Expansion
The term adiabatic implies a boundary which heat cannot cross. In other words all the energy of an adiabatic expansion is provided by or given to the gas, and results in the gas gaining or losing temperature according to the definition of heat capacity:

E = n * Cv * (T0 - T)

where E is the energy absorbed or provided by the gas, Cv is the heat capacity of the gas at constant volume ( the gas does no work at constant volume) times the temperature difference. "n" is the amount of gas so Cv would be heat capacity per unit amount of gas. The above equation written in differential form would be:

dE = n*Cv*dT

Since work is equal to force times distance or pressure times volume:

dE = P*dV

and n*Cv*dT = -P*dV

The minus sign indicates that the temperature must drop when doing the expansion work. Substituting the ideal gas equation gives:

n*Cv*dT = -nRT*dV/V which separating the variables gives

Cv*dT/T = -R*dV/V

It can be shown that for an ideal gas, Cp - Cv = R, where Cp is the heat capacity at constant pressure. If we apply heat to a gas at constant pressure, it must expand to keep the constant pressure, so it is doing pressure-volume work - which explains why Cp is greater than Cv. The ratio of Cp/Cv is commonly referred to as "gamma". Substituting gamma we have:

R/(gamma-1) = Cv

which is really the definition of gamma in the non-ideal gas case. After integrating we have:

ln(T2/T1) = -(gamma-1)*ln(V2/V1) or

T2/T1 = (V1/V2)(gamma-1) or from the ideal gas law

P1*V1gamma = P2*V2gamma

The above results are important when solving the internal ballistic problem after the powder is burnt, which is basically an adiabatic expansion case. Actually there is heat loss to the barrel, but that can be accounted for by adjusting gamma.

Energy of an adiabatic expansion.
The integral of P*dV is the energy of an expansion. From above

P = Pi*Vigamma * V(-gamma)

where P is the pressure at volume V and Vi, Pi represent the initial volume and pressure. Integrating P*dV from Vi to V gives the energy of expansion to volume V.

E = integral(Pi*Vigamma*V(-gamma)*dV ) from Vi to V

= Pi*Vi/(1-gamma)*[(V/Vi)(1-gamma) -1 ]

The Energy equation
The work done by the gas in the internal ballistic problem goes into heating the barrel, and doing pressure-volume expansion work, part of which results in the acceleration of the bullet. The work done by the gas can then be equated in terms of the heat capacity and temperature difference from above to the pressure volume work and heat loss:

C*z/mw*Cv*(T0-T) = A*integral(P*dx) + Eh

C is the powder charge, z is the mass fraction of gas, so C*z = m, the mass of gas.

m/mw = n.

This energy is equal to the pressure volume work done by the gas plus the heat lost to the barrel (Eh). The Pressure times area (A) is force, and the integral of force over the distance is work. Substituting our equation of state P*(V-b)=RT/mw, eliminating T.

C*z/mw*Cv*T0 = C*z*Cv*P*(V-b)/R + A*integral(P*dx) + Eh

substituting for Cv from:

(gamma-1) = R/Cv

C*z*R/mw*T0/(gamma-1) = C*z*P*(V-b)/(gamma-1) + A*integral(P*dx)+Eh

and introducing force constant F=R/mw*T0

F*C*z/(gamma-1) = P*C*z*(V-b)/(gamma-1) + A*integral(P*dx) + Eh

V is the volume per unit mass, so C*z*V is the total volume occupied by the gas, which is equal to the chamber volume "K" minus the volume of the solid propellant plus the volume of the bore behind the bullet A*x. So if "d" is the density of the propellant, then

C*z*V = K + A*x - C*(1-z)/d

So the energy balance equation becomes:

F*C*z/(gamma-1) = P/(gamma-1)*(K+A*x-C/d-C*z*(b-1/d))+A*int(P*dx)+Eh

Since K-C/d is the initial free space in the case, we can write

K-C/d = A*L, where L is the effective length of the free space

in the chamber as if it were the same cross sectional area as the bore. Then we can write:

F*C*z/(gamma-1) = P/(gamma-1)*(A*(x+L)-C*z*(b-1/d)) +
A*int(P*dx) + Eh

If the Eh is neglected and the pressure P in the expansion integral is assumed to be the pressure at the base of the shot, the resultant equation is known as Resal's equation.

The Lagrange Pressure Gradient
The pressure in Equation 4 should be taken as the average pressure since it was derived from the equation of state of the gases. We cannot equate this pressure with the pressure at the base of the shot to use with the equation of motion of the shot, since there will be a pressure gradient from the breech of the gun to the base of the shot due to the inertia of the powder gases. Lagrange solved this problem by considering a volume element at position "sigma" where sigma is a fraction of the distance from the breech to the shot base. In this manner the sigma (designated here as "s") is independent of time. If V is the volume at any moment between breech and shot base (the volume of the powder is ignored), then s*V will be the volume behind the cross section at "s". A volume element at "s" will have a mass of p*V*ds where p is the density (rho) of the gas. The velocity of the element will be s*v where v is the velocity of the shot. The momentum of the volume element is then s*v*p*V*ds. The time derivative of the momentum gives the inertial force which is equal to the force from the pressure on the section so:

d(p*V*v*s*ds)/dt = -A*dP/ds * ds or

s*d(p*V*v)/dt = -A*dP/ds

where P is the pressure. Integrating this from s at pressure P to the shot base at pressure Ps, s=1, gives:

A*(P-Ps) = integral( d(p*V*v)/dt *s*ds )

Now substitute the equation of motion A*Ps=w*dv/dt for dt

(P-Ps)/Ps = integral( d(p*V*v)/dv *s/w*ds)

Since the pressure gradient is small in proportion to the absolute pressure, the variation of the density "p" with s is neglected so p*V = C*z and integrating gives:

(P-Ps)/Ps = C/(2w)*d(z*v)/dv*(1-s^2)

If the above equation is solved for the breech pressure Pb, where s=0, and the result combined with the original equation:

P-Ps = (1-s^2)*(Pb-Ps)

The average pressure Pm is determined by the integral

Pm = integral( P*ds) from s=0 to s=1.

If this is done using P from the above equation, the result is:

Pm = 1/3*(2*Pb + Ps)

Also from above when solving for Pb at s=0 z=1 and v=0

Pb/Ps = (1-C/(2*w))

thus giving the relationship between average, breech and shot base pressure:

Ps = Pb/(1+C/(2*w)) = Pm/(1+C/(3*w))

This approximation neglects the fluid friction of the gas which may be important at high velocities, and also neglects the gas density variation, the powder volume and movement, and is really derived based on an all burnt charge. The extra friction towards the muzzle cancels the errors near the breach to some extent, so the net result of the approximation is pretty good. The kinetic energy of the gases can be found by integrating the kinetic energy of volume elements over s similar to what was done above so:

KEgas = integral( 1/2*p*V*s^2*v^2*ds ) from 0 to 1

which using p*V=C*z again gives:

KEgas = 1/6*C*z*v^2

Energy equation continued
Let us consider the expansion energy term in Equation 4. This energy represents the kinetic energy and rotational energy of the projectile, the frictional losses, the kinetic energy of the gas, losses due to recoil of the gun and even the strain energy in expanding the gun barrel. Another factor is the bullet engraving energy which may be appreciable especially in pistols compared to the available powder energy. Coppock's model assumes that of 5% of the energy of the bullet goes into friction and recoil (1 or 2 % effect). The other losses are very small. The rotational energy is about 0.5%, and the strain energy is less than a percent and are neglected. The friction is taken into account by increasing the mass of the bullet by the 5%. This implies that the friction is proportional to the force on the bullet base, which is not too good an assumption since there would be a component that would be fairly independent of the pressure or position of travel down the bore. The assumption is used since it makes the problem solvable analytically. The engrave force is not taken into account in this model and would be an important factor to include in a more advanced model. The kinetic energy of the powder gases was shown to be 1/6*C*v^2, (at all burnt) so combining these terms:

A*int(P*dx) = 1/2*(w*1.05)*v^2 + 1/6*C*v^2

These terms can be combined into a single kinetic energy term:

1/2*w1*v^2 , where w1 = 1.05*w + 1/3*C

Next, adding Eh, the heat loss to the barrel in Resal's equation:

F*C*z/(gamma-1) = P/(gamma-1)*(A*(x+L)-C*z*(b-1/d)) + 1/2*w1*v^2 + Eh

If we play a similar game with Eh, and write it as a fraction "k" of the kinetic energy term

Eh = k*1/2*w1*v^2

then

F*C*z = P*(A*(x+L)-C*z*(b-1/d)) + (gamma-1)*(1+k)*1/2*w1*v^2

Thus, if we define a new gamma, "gammap" that would be in essence the effective gamma, we could retain the original form of the Resal's equation if:

(gammap-1) = (gamma-1)*(1+k)

From above, k = Eh/Es where Es = 1/2*w1*v^2

Then

(4) F*C*z = P*(A*(x+L)-C*z*(b-1/d)) + (gammap-1)*1/2*w1*v^2

This manipulation implies that the heat loss at any instant is equal to a constant fraction (k) of the shot energy. This assumption has been shown to be good to around 20%. This does not imply that the error in calculating the velocities and pressures are this large, however, since the net energy balance might be quite good. The problem is that to compute

Es = 1/2*w1*v^2

we need to know the final bullet velocity "v". The program achieves this by iterating the calculation several times, using the computed final velocity as an estimate each time until convergence is achieved. The value of Eh, the total heat loss to the barrel is calculated using Thornhill's semi-empirical formula which is a function of the powder charge, (T-T0), and the bore dimensions. Thornhill's equation is the only empirical estimate used in this program.

Thornhill equation
Thornhill derived a formula based on test firings combined with theoretical results for the total heat lost to the barrel (cal) of a gun as:

Eh = 10.13*H*d*Vol/A

where H=.0127*T*sqrt(d)*R

and T is the maximum temperature of the barrel

d is the bore diameter (in)

A is the area of the bore (in^2)

Vol is the total volume of the gun (in^3)

R is a hydrodynamic roughness factor which ranges from 1.25 in big guns to 1.4 or more in small arms

T = (T0-300)/(1.7+0.38*d^.5*(d^2/C)^0.86)

where ambient is 300 deg K

C is the charge in lbs

This reduces to the following in ft*lbs units:

Eh = 0.397*d^(3/2)*Vol/A*T*R

Summary of the Equations
There are 4 basic equations that describe the system in Coppock's model:

1) The powder burn rate equation.

-D*df/dt = beta*Pb (1)

2) A powder form function that relates mass of gas produced to the linear fraction of the powder grain that has burned.

z = (1-f)*(1+theta*f) (2)

3) The equation of motion.

Ps(x)*A = w*dv/dt (3)

4) The equation of state or energy balance.

(4) F*C*z/(gammap-1) = Pm/(gammap-1)*(A*(x+L)-C*z*(b-1/d)) +

1/2*w1*v^2

The effect of covolume and powder density:
It is interesting to consider the effect of including these terms. Equation 4 contains the term (b-1/d). If b = 1/d then the whole term drops out and the equation is simplified considerably. Many early treatments of the problem have made this assumption. In reality, the covolume "b" is around .95 cc/g and 1/d is around 0.62 cc/g and its net effect would be to increase the effective force constant of a simplified equation by about 10%. Note that if one were to include the effect of the increase in volume due to the burning powder solid, and neglect covolume, that the result would be worse than neglecting both effects. The effect of the initial volume displaced by the solid powder is an important effect in either case.

Coppock's Solution
Equation 1 and 3 by substituting for Pb and Ps from the Lagrange relation and integrating yields:

(5) v = A*D*(1-f)/(beta*(w+1/2*C))

giving velocity as a function of fraction burned "f". At "all burnt", f=0 and the velocity can be read directly. The final velocity can be computed from the result of the following "adiabatic" expansion, but one needs to know the "x" value at all burnt in order to figure the expansion ratio from that point. The other 3 equations can be combined and simplified to a differential equation with unitless coefficients by defining the following:

b_av is the breech to average pressure ratio

b_av=(1+C/(2.*w*1.05))/(1+C/(3.*w*1.05))

M = A*A*D*D/(beta^2*b_av^2*w1*F*C)

theta1 = theta + 1/2(gammap-1)*M

Z = 1 - (gammap-1)*M/2 + theta1*f

B = (b-1/d)/(A*L)


This is the resultant diff. eq.

(6) Z*dx/df + M*(x+L) = M*B*L*z

Integrating this gives "x" as a function of "f", from which we get "x" at all burnt (f=0) or "xb".

Equation 4 and 5 give:

(7) A*Pm*(x + L*(1-Bz)) = C*F*Z*(1-f)

giving the pressure as a function of "x" and "f". Combining (6) and (7) and taking dP/df = 0 gives the maximum pressure, but this gets a bit involved. The details are not presented here, but the complete formulas are available in the Mathcad(TM) example. The only thing left is to compute the adiabatic expansion from the all burnt point. The adiabatic expansion equation gives:

P = Pb*(V/Vb)^(-gammap)

where V is the total volume behind the bullet and Vb is the volume at all burnt.

V/Vb = (x + L*(1-B))/(xb + L*(1-B))

and the final velocity is:

v^2 = C*F/w1*(M + Zb*Phi)

where Phi = 2/(gammap-1)*(1-(V/Vb)^(1-gammap)),

and Zb is Z at all burnt.

Well, all that is beyond my grasp of mathematics and internal ballistics, so, I will just post my results. I own a P-64 "Westerner" in nearly new condition and tried RE-22 in it with 125 and 140 NPs and obtained pressure signs with slow velocities. I went to IMR-7828 and with Win. brass and CCI 250 primers I use 65 grs-125 NP and 63 grs.-140 NP, the velocities over three different chronographs are 3350 and 3250 respectively and it shoots better than my 59 yr. old eyes can, this with a Leupy 3.5x10 HD, not really a target scope.

This will outdo any of the dozen .270s I have owned and shoots flatter than piss on a plate, I have a Micky G&H stock on it and it is a nice rifle that I almost never use. Downwind has seen this one and some of my others on our club range.

Steve....all that brings back fond memories of when I was a chemistry major (with minor in physics).

Anyways, I like 63.0 grs of Retumbo under 140s....not max, but very accurate in my 264s.

Lee Martin
http://www.singleactions.com

Ricciardelli,

Your last post would have more meaning to most of the members of this forum if it was concluded with a numeric ranking of the powders under discussion as to burn rate.

Those same members would also then be able to judge as to whether factual observations coincided with your mathematical predictions.

I have only burned a few pounds of H870 and RL25, but from my observations in the 264 Win mag with 140 gr bullets and 7mmSTW with 160 gr bullets, your definition of "similar burning characteristics" is far removed from mine.

Steve: What was your hypothesis, what is your conclusion? All I see is a bunch of formulae, without any basis. For those of us who might be a little slow on the uptake, what are you trying to say?

Does all your cutting and pasting prove that:

"RL-25 and H-870 (as well as AR-2214) have similar burning charasteristics"?

The following are three currently accepted burn rate charts for the slower burning powders - that is, according to published industry data. My experience with these powders is that this order is right on the mark, although H870 and the other 50BMG powders are significantly slower than Re25, Retumbo, and MRP-2.

I would love to hear what people's experience has been with Retumbo, MRP-2, Re25, AR2218, and N170. Do we have some Australian contributors who can testify to AR2218 ("H50BMG"), which according to QL is absolutely SPECTACULAR in big bore mags. Yet, at the same time, QL shows H50BMG as not being that great - what gives?

123. IMR 4350
124. Hodgdon H4350
125. Norma N204
126. Ramshot Hunter
127. Alliant RL19
128. Vihta Vuori N160
129. Vihta Vuori N560
130. IMR 4831
131. Scot Brig 4831
132. Norma N205
133. Accurate XMR 3100
134. Winchester WMR
135. Hodgdon H4831
136. Norma MRP
137. Alliant RL22
138. Winchester 785
139. Hodgdon H450
140. Accurate Mag Pro
141. Vihta Vuori N165
142. Winchester WXR
143. IMR 7828
144. Accurate 8700
145. Hodgdon H1000
146. Ramshot Magnum
147. Alliant RL25
148. Hodgdon Retumbo
149. Hodgdon H870
150. Vihta Vuori N170
151. Vihta Vuori 24N41
152. Hogdon 50 BMG
153. Vihta Vuori 20N29



152. H4831 (Hodgdon)
153. MRP (Norma)
154. Reloader 22 (Alliant)
155. 785 (Winchester)
156. H450 (Hodgdon)
157. Mag Pro (Accurate)
158. N165 (Vihtavuori)
159. WXR (Winchester)
160. 7828 (IMR)
161. 8700 (Accurate)
162 H1000 (Hodgdon)
163. AR2217 (ADI)
164. Magnum (Ramshot)
165. Reloader 25 (Alliant)
166. AR2225 (ADI)
167. Retumbo (Hodgdon)
168. H870 (Hodgdon)
169. N170 (Vihtavuori)
170. 24N41 (Vihtavuori)
171. 50 BMG (Hodgdon)
172. AR2218 (ADI)
173. 20N29 (Vihtavuori)



83. Accurate Arms 4350
84. NORMA 204
85. Vihtavuori N550
86. Alliant Reloder 19
87. IMR, Co IMR4831
88. Accurate Arms 3100
89. Vihtavuori N160
90. Hodgdon H4831 & H4831 SC
91. NORMA MRP
92. Alliant Reloder 22
93. Vihtavuori N165
94. IMR, Co IMR7828
95. Vihtavuori N170
96. Hodgdon H1000
97. Alliant Reloder 25
98. Hodgdon Retumbo
99. Accurate Arms 8700
100. Hodgdon H870
101. Vihtavuori 24N41
102. Hodgdon H50BMG
103. Vihtavuori 20N29

My order was RL-25,Retumbo,Mag-Pro,and the slowest, Magnum.That's with powder lots I had and My 264.

Yes I see that you have the powders listed from fastest to slowaest, similar to the charts supplied by many powder companies. But you do not show how much faster or slower.

Your chart shows H870 as being a faster powder than RL25. In my experience, H870 is far slower, and the reloading manuals show much larger charges for H870 in the cartridges with which I am familiar.

I am curious, was this chart totally mathematically derived from observed physical and chemical characteristics of the powders, or did the ranking also include test firing in various cartridges?

1 R-1 2 Bullseye 3 AP-30N 4 BA-10 5 P-803 6 S-121
7 N-310 8 AS 9 Competition 10 N-31 11 Nitro 100 12 Titewad
13 Red Dot 14 Clays 15 700-X 16 N-2010 17 N-312 18 Solo 1000
19 N-318 20 Promo 21 Titegroup 22 Trap 100 23 W-452 24 Zip
25 N-320 26 WST 27 American Select 28 MS-200 29 Royal Scot 30 W-231
31 International 32 Green Dot 33 PB 34 BA-9 35 N-321 36 P-805
37 Solo 1250 38 453 39 N-324 40 Silhouette 41 AA-2 42 HP-38
43 WSL 44 Unique 45 AO 46 N-325 47 SR-7625 48 N-330
49 A-1 50 Power Pistol 51 AA-1250 52 AL-5 53 Universal 54 AL-7
55 Base 56 D-20 57 MP-200 58 N-331 59 P-804 60 W-473
61 AA-5 62 WSF 63 Herco 64 SP-8 65 True Blue 66 N-340
67 Pearl Scot 68 800-X 69 AP-90N 70 HS-6 71 W-540 72 3N-37
73 SP-2 74 WAP 75 SR-4756 76 Solo 1500 77 AP-100N 78 HS-5
79 N-350 80 S-221 81 AA-7 82 HS-7 83 Blue Dot 84 N-105
85 W-571 86 Enforcer 87 Longshot 88 Steel 89 W-630 90 AA-9
91 2400 92 N-110 93 R-123 94 BA-6 95 Lil'Gun 96 P-806
97 H-110 98 W-296 99 IMR-4227 100 AA-4100 101 AR-2205 102 S-265
103 SR-4759 104 H-4227 105 AA-5744 106 SP-3 107 N-120 108 AA-1680
109 N-200 110 W-680 111 H-4198 112 IMR-4198 113 RL-7 114 AR-2207
115 N-125 116 S-321 117 TU-2000 118 N-201 119 H-322 120 AA-2200
121 N-130 122 Xterminator 123 AA-2015 124 N-132 125 N-133 126 Brigadier 4197
127 IMR-3031 128 Benchmark 1 129 S-335 130 SP-9 131 RL-10 132 IMR-4895
133 Benchmark 2 134 SP-7 135 AA-2230 136 H-335 137 N-134 138 R-902
139 TAC 140 Brigadier 3032 141 AA-2460 142 H-4895 143 N-135 144 SP-10
145 RL-12 146 AA-2495 147 IMR-4320 148 AR-2206 149 TU-3000 150 W-748
151 IMR-4064 152 Brigadier 4065 153 AA-2520 154 N-202 155 RL-15 156 AR-2208
157 N-140 158 R-903 159 S-341 160 TU-5000 161 Varget 162 BL-C(2)
163 N-540 164 Big Game 165 N-203 166 H-380 167 AA-4064 168 R-907
169 H-414 170 N-150 171 S-361 172 AA-2700 173 W-760 174 AR-2209
175 R-904 176 IMR-4350 177 H-4350 178 S-365 179 TU-7000 180 N-550
181 AA-4350 182 N-204 183 Brigadier 4351 184 RL-19 185 IMR-4831 186 AR-2213
187 H-450 188 Magnum 189 Magpro 190 R-905 191 W-785 192 N-160
193 H-4831 194 AA-3100 195 MRP 196 N-560 197 RL-22 198 S-385
199 TU-8000 200 WXR 201 N-165 202 IMR-7828 203 H-1000 204 AR-2217
205 MRP-2 206 S-371 207 WMR 208 N-170 209 Retumbo 210 H-870
211 AR-2214 212 RL-25 213 AA-8700 214 24N-41 215 20N-29 216 24N-21
217 H-50BMG 218 AR-2218 219 H-5010 220 W-870 What A Friggin' Mess!

Last Updated on 08/23/04
Again, these are approximate burning rates.

If this chart was derived without test firing of the powders, I am amazed at how closely it does comply with observed data.

The data in my chart is derived from actual firings.

And actually, as the notation at the bottom states, powders in the same color group have similiar burning properties...BUT ARE NOT IDENTICAL. RL-25 and H-870 are similar.

In addition to all this BS, there can be as much as a 5% difference in the burning characterists of the same powder, but a different lot number.

Placew a firecracker in your open hand and light it. When it goes bang, you may have a burned hand. However, place that same firecracker in a closed fist and light it...the results are totally different.

I think I`ll just stick to my old loading of 73.2/H-870 and the 140 Sierra Gameking. It has worked for me for over 30 years. H-870 is still found in gunshows, garage sales etc. I recently acquired a 8# container for 45.00. That`ll last me the rst of my life. Always gave me the good velocity and excellent accuracy in any of 7-10 264s I have had over the years. Been all over the world with this load and never had problems either. Just my .02.

Aloha, Mark

Aloha, Mark

quote:

Originally posted by Bohica:
I think I`ll just stick to my old loading of 73.2/H-870 and the 140 Sierra Gameking. It has worked for me for over 30 years. H-870 is still found in gunshows, garage sales etc. I recently acquired a 8# container for 45.00. That`ll last me the rst of my life. Always gave me the good velocity and excellent accuracy in any of 7-10 264s I have had over the years. Been all over the world with this load and never had problems either. Just my .02.

Aloha, Mark

Aloha, Mark

WOW! Someone finally agrees with me on something!!

My favorite load:
Bullet: 140 Grain Sierra HPBT
Powder: 73.0 grains of Hodgdon H-870
Primer: Winchester WLR
Case: Winchester
Firearm: Winchester Model 70
Optics: Leupold 3x9
Velocity: 3132 FPS @ 15' from muzzle
Accuracy: 5-shot, 200-yard, 1/2" to 3/4"