So bear with me this is kind of a weird/different question. A 308 win can't push a 168gr bullet as fast as a 30-06 just as a 30-06 can't push a 168gr bullet as fast as a 300 win mag because of case capacity with current powders. So my question is why couldn't there be a powder that say could produce 30-06 pressures in a 308 case size or even 300 win mag pressures in a 308 case size. I guess what I am really wondering is the barrels are really the same just the chamber being reamed for what ever cartridge correct? Is it because of the time it takes to make the pressure? I know this is a very different kind of question. Just the kind of shit I think about when I am at church.....lol
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Gunsmithing Could a "super powder" be used to push a bullet faster without blowing up barrel?
- Thread starter Steel+Killer
- Start date
The pressures are relatively close to the same for those cartridges, it is the volume of gas that maintains a higher pressure with the bullet further down the muzzle, but the peak pressures are about the same.
Incredibly complex topic. I only know enough to be dangerous. That said, we're talking transfer of chemical potential energy into kinetic energy. In short, a 300 win mag has more chemical potential to turn into kinetic energy.
Each powder is chemically different and reacts differently, and differently still under various temp/pressure conditions. Never mind all of the flash retardant and other additives present. Then there is efficiency of the transfer. Two cases with different geometry but the same volume and caliber will produce different velocities with the same type/amount of powder... there's also losses to heat transfer to the barrel and air.
It's not as simple as more pressure equals more velocity... You see that very quickly loading a 308 with pistol powder (don't do it). You get massive overpressure and garbage velocity.
About the closest thing to what you're talking about would be to try to stack progressively faster burning higher energy powders in the case in hopes of maintaining a higher energy transfer rate longer throughout the length of the barrel. Voodoo.
Bear in mind a lot of this has to be throttled to keep jackets from shearing or melting etc... Like you could maybe use a 12" barrel and alloy steel cases and c4 for propellant and get the same or better velocity, but the bullet has to live through the greater acceleration and pressures on the ass end.
Each powder is chemically different and reacts differently, and differently still under various temp/pressure conditions. Never mind all of the flash retardant and other additives present. Then there is efficiency of the transfer. Two cases with different geometry but the same volume and caliber will produce different velocities with the same type/amount of powder... there's also losses to heat transfer to the barrel and air.
It's not as simple as more pressure equals more velocity... You see that very quickly loading a 308 with pistol powder (don't do it). You get massive overpressure and garbage velocity.
About the closest thing to what you're talking about would be to try to stack progressively faster burning higher energy powders in the case in hopes of maintaining a higher energy transfer rate longer throughout the length of the barrel. Voodoo.
Bear in mind a lot of this has to be throttled to keep jackets from shearing or melting etc... Like you could maybe use a 12" barrel and alloy steel cases and c4 for propellant and get the same or better velocity, but the bullet has to live through the greater acceleration and pressures on the ass end.
Sounds like what Hornady attempted with their Superformance line. Again, there a lot of factors that come in to play...but roughly a 100-200fps gain was the goal.
https://www.loaddata.com/Article/Ben...nce-Powder/140
https://www.loaddata.com/Article/Ben...nce-Powder/140
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Duplex an triplex powder loads were tried long ago to maintain peak pressure an they worked well, although the correct timing delays had to be used an placed properly. There was no forgiveness if you hosed up the recipe.
If you compare today’s velocities with those of early smokeless loads in the same cartridge, the newest powders are doing some pretty awesome things. Powders like reloder 17 and 26(there are others of course) produce high average pressures without exceeding maximum pressures. A perfect powder would go instantaneously to peak pressure, then stay there until the bullet exited. If you google around for pressure traces you’ll see just how short the pressures at at or near peak.
Interesting read, with some graphs
http://www.accuracy-tech.com/wp-content/uploads/2016/03/Powder-Burn-Rate-Effect.gif
Interesting read, with some graphs
http://www.accuracy-tech.com/wp-content/uploads/2016/03/Powder-Burn-Rate-Effect.gif
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The physics of your logic are flawed (as someone else already pointed out), but the thought is good.
So good, in fact, that Hornady beat you to it: https://www.hornady.com/ammunition/superformance#!/
It's a cubic inches = horsepower thing.
Case size and powder weight plus bore size = velocity potential based on bullet weight and shape.
Compare equal cases with different neck diameters and you can see where what you are asking cannot apply.
243 Winchester
260 Remington
7mm-08 Remington
308 Winchester
358 Winchester
If you could find a common bullet weight to use in each case, their maximum velocity won't be the same. That's the expansion ratio controlling pressure and velocity.
In your question, you're asking if a 308 could operate at 30-06 pressure. In fact a 308 operates at a higher pressure than the '06. So does the 300 WM.
There's no way to get the VELOCITY you're wanting from the smaller case. To even attempt it would be extremely dangerous.
You're looking at approximately 60,000 psi right in front of your face. 60k psi is the normal operating pressure.
I've worked with pressure test barrels and have seen the results of trying to do more with less.
It's fucking dangerous as hell.
Proof loads are used to test the safety margin of the firearm. They are dangerously high, yet safe for firing one or two cartridges. (To test the structural safety only, not for any routine use.)
Some people believe their loads are safe as long as they eject easily. Their primers are flattened, the case web expands, and primer pockets last three or four firings.
These same people wonder why they have difficult extraction and hard bolt lift.
The simplicity to all of this is:
If you have a caliber, bullet weight and velocity combination that will suit your hunting or target needs, buy a gun that shoots that combination with ease.
Don't try and turn a Toyota Tercel into a 1/4 mile dragster. It won't work and you'll break it trying to do so.
Case size and powder weight plus bore size = velocity potential based on bullet weight and shape.
Compare equal cases with different neck diameters and you can see where what you are asking cannot apply.
243 Winchester
260 Remington
7mm-08 Remington
308 Winchester
358 Winchester
If you could find a common bullet weight to use in each case, their maximum velocity won't be the same. That's the expansion ratio controlling pressure and velocity.
In your question, you're asking if a 308 could operate at 30-06 pressure. In fact a 308 operates at a higher pressure than the '06. So does the 300 WM.
There's no way to get the VELOCITY you're wanting from the smaller case. To even attempt it would be extremely dangerous.
You're looking at approximately 60,000 psi right in front of your face. 60k psi is the normal operating pressure.
I've worked with pressure test barrels and have seen the results of trying to do more with less.
It's fucking dangerous as hell.
Proof loads are used to test the safety margin of the firearm. They are dangerously high, yet safe for firing one or two cartridges. (To test the structural safety only, not for any routine use.)
Some people believe their loads are safe as long as they eject easily. Their primers are flattened, the case web expands, and primer pockets last three or four firings.
These same people wonder why they have difficult extraction and hard bolt lift.
The simplicity to all of this is:
If you have a caliber, bullet weight and velocity combination that will suit your hunting or target needs, buy a gun that shoots that combination with ease.
Don't try and turn a Toyota Tercel into a 1/4 mile dragster. It won't work and you'll break it trying to do so.
The key to obtaining higher velocities is not to improve the existing technology but to develop a new technology. We can achieve superior long range accuracy by looking at what has already been done with tank munitions. There is no reason why we can't develop a smooth bore or shallow rifled longarm shooting a discarding sabot, fin stabilized projectile. There would be challenges in recoil management and also possibly legality (for military and hunting). Civilian manufacturer's have no desire to do this because there is a limited interest in the civilian market. There has been some work done on this by the military.
Rick,
have you ever used sabots to shoot 22 bullets out of 30 cal barrels?
I've wondered about the feasibility of using 6.5 or 30 cal out of a 338 or 35 cal barrel using a larger sabot.
Flechettes would be a hoot on varmints
have you ever used sabots to shoot 22 bullets out of 30 cal barrels?
I've wondered about the feasibility of using 6.5 or 30 cal out of a 338 or 35 cal barrel using a larger sabot.
Flechettes would be a hoot on varmints
Mike, my only experience has been with tank munitions. The muzzle loading community has already embraced the sabot for the higher velocity and bullet choices the technology makes available. Here are some experimental rifle sabot rounds.
"However, this concept in the context of military small arms has been experimented with for well over the past 50 years, and hasn’t yet reached production status, which indicates that serious downsides exist. Typically, sabots significantly reduce the accuracy of the gun, as clean, repeatable separation of a small-caliber sabot from the projectile is very difficult to achieve. As a result, the dimensional tolerances of the sabot and projectile both need to be kept very small, which increases the cost of ammunition."
"However, this concept in the context of military small arms has been experimented with for well over the past 50 years, and hasn’t yet reached production status, which indicates that serious downsides exist. Typically, sabots significantly reduce the accuracy of the gun, as clean, repeatable separation of a small-caliber sabot from the projectile is very difficult to achieve. As a result, the dimensional tolerances of the sabot and projectile both need to be kept very small, which increases the cost of ammunition."
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While on the technical side, I deal with solid rocket propellants more than smokeless gunpowder, they are pretty similar. It has to do with gas volume vs pressure and keeping away from the "knee". If you look at one propellant (call it A) that produces 1 volume of gas at say 40Kpsi with a fast rise, but a flat curve as the baseline, you then look at B that produces 110% of the gas volume, but has a peak that is at 45Kpsi and C that produces 120% of the gas volume with a knee, that when you hit 46Kpsi goes from deflagration to explosion (the remainder of the gas volume is essentially produced instantly) and a peak of say 150Kpsi...you have found your failure limit. The goal is the largest area under the curve without the knee. We use bomb calorimeters to get total energy and gas volume (easy) and then it gets complicated measuring pressures. We use very small amounts, but start off in vessels that are pressurized before the propellant is ignited. Energy released is the same, it is how that energy is released that is harder to predict, and control. That "reloaders" are prone to hot rod likely keeps some propellants and loads from being available due to the liability that having a "knee" will produce.
Changes in propellants have given us better efficiency in the last 50, then 20 years, but there is only so much there chemically with the current technology. Are there other technologies chemically and mechanically? Sure. Will they be driven to the consumer markets? I doubt it.
Changes in propellants have given us better efficiency in the last 50, then 20 years, but there is only so much there chemically with the current technology. Are there other technologies chemically and mechanically? Sure. Will they be driven to the consumer markets? I doubt it.
Mark,
when you say "knee" are you referring to the rapid rise and rapid drop in pressure that some powders experience when used for cartridges they weren't designed for?
when you say "knee" are you referring to the rapid rise and rapid drop in pressure that some powders experience when used for cartridges they weren't designed for?
I guess this is where my thought is......logically it just seems (to my untrained mind) that more pressure would equal more velocity. So having a bigger case means that there is more time for the pressure to act on the bullet without blowing up the barrel? Thanks to every one for their input I appreciate it.
First, you have to understand the basic principle of smokeless powder. The burn speed was determined by the size of the kernel, or ball. The nitrocellulose used burns at the same speed, but how much of it burns at a time was dampened by thickness and length of the kernels or ball. Nitrocellulose alone is called single based powder. Then we get to double based powders, where nitroglycerin was added. This adds pressure. All ball powder is double based, i.e. Win 748 and 760, but there are "extruded" double based powders, i.e. Alliant Re-10/12/15/17/19 etc. Double based powders burn a little slower but since they produce more pressure, they SORT OF equivalate to extruded single based powders. But, because of pressure differences, they DO NOT convert straight across. Interpolation can be used as a means to find a starting load if you cannot find data to work up from. But, you have to understand the comparisons of different cartridges and the powders you are comparing in them to find the minimum load to work up from for your bullet/powder/cartridge combination.
That said, You've already seen the first generations of "super powders". If you were to take the old IMR and Hodgdon powders (made by DuPont, who owned IMR) they were like metering boulders through the powder measures. The size of the kernel was how they determined burn speed. Then, along came the Hodgdon Extreme line-up and you would see a HUGE difference. The kernels are roughly half the size. The kernels are spray coated with a burn retardant to slow the burn. They are pretty much all new powders. But, to avoid too much confusion, (continueum marketing) they maintained the old ID numbers as that is what they were chemically formulated to duplicate.
The "even newer" generation of powders does basically the same thing, but they mix the burn retardant integrally (RE-17 & IMR 8208 XBR). Spraying on the burn retardant gave a good replication of the intended powder, but burned off quickly. Mixing the powder throughout the kernel/ball has made the chemical breakdown, or rapid oxidation of the burn retardant much smoother. Both of these tend to give what I call a "soft pressure ceiling". Burn retardant is basically inert chemical that won't react until it hits a certain pressure or temperature. Then that molecule "cracks" and free radicals go off to join other free radicals and make a new molecule. One example of this is molecules heavy with hydrogen, which combines well with carbon, and oxygen (think rust, feris oxide). Once temp/pressure get high enough then the hydrocarbons and oxy-whatever molecules break up. Hydrogen and Oxygen LOVE each other and make water...cooling the burn. Just a rudimentary example of how this is being done, not that this is the actual formula being used.
With the burn retardants being used today it is important to stop when the book says so, instead of doing what many of us have always done and that is work up until you see pressure signs. A good example is RE-17. You won't see pressure signs until you are way above what should be for the max load. The retardant, as it is being chemically used, will keep pressure down. But, when you've burned through the retardant, you are basically left with a hot load of fast powder. And nothing more to cool the burn. You will go from no sign, no sign, to damn! blown primers!...or worse.
As to super powders, I'm surprised we don't see more liquid chemical propellants that start like how we make det. chord for explosives. It could be poured into cases and allowed to cure hard for ignition.
One big drawback to a number of advancements is the inability to dissipate heat from the firing process. So far brass has still shown to be the best for taking the heat out of the weapon in sustained firing tests. Another big drawback is literally how easy it is to make smokeless powder vs. a lot of other chemical products.
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Yes, that can and will create a knee given the right conditions. So too will pressures above (or below) normal, in some cases create rapid rises or decreases in the slope of the pressure curve. Doing my best to put a complex issue into more common terms.
There are powders out there now (an have been for many many years) that will safely push a 30cal 190gr smk 17-22fps faster than Varget will ever push a 175smk. the draw back is your brass is one an done. There will not be any bolt lift issues, ejector or extractor marks but the primer pockets will never retain another primer again. If you don't care about that issue 190's are the ticket in a 308, as these burn rate powders will never hit critical peek pressure, they just hold the max safe pressure much, much longer. They are listed in most load books, remember the book is just a guide line.
That said, remember never exceed what your loading manual says,
That said, remember never exceed what your loading manual says,
