308 accuracy load
04-07-2009 | 03:12 PM
#31
Typical Buck
Joined: Jun 2005
Posts: 604
Likes: 0
RE: 308 accuracy load
ORIGINAL: stubblejumper
How are you igniting that powder?With a match?How much powder at a time?
The powder in a cartridge case is held in a narrow column just in from of a primer that releases a great deal of energy that blasts a flame into that narrow column of powder igniting much of it at once.Therefore you get very complete ignition,and a very fast burn time.
That is not at all the case if you throw a pile of powder on the ground and throw a match into the pile.A match is not even close to as hot as a primer,and it is not driving a flame into much of the powder at once.
Try an experiment if you want to see just how the method of ignition effects the burn time.
Place 100gr of powder onto the ground and spread it as thin as you can.Throw in a match and see how long it takes to burn.
Take another 100gr of the same powder,and pile it into as small of a pile as you can.Light an oxy-acetylene torch with a large tip and quickly hold the torch flame right over the powder.Notice how much quicker it burns when it is concentrated together and has a much more powerful ignition source that can ignite much more of it at once.
I will leave with one last question to ponder. If pressure does not affect burn rate why does it take powder so long to burn when ignitedoutside a vessel?
The powder in a cartridge case is held in a narrow column just in from of a primer that releases a great deal of energy that blasts a flame into that narrow column of powder igniting much of it at once.Therefore you get very complete ignition,and a very fast burn time.
That is not at all the case if you throw a pile of powder on the ground and throw a match into the pile.A match is not even close to as hot as a primer,and it is not driving a flame into much of the powder at once.
Try an experiment if you want to see just how the method of ignition effects the burn time.
Place 100gr of powder onto the ground and spread it as thin as you can.Throw in a match and see how long it takes to burn.
Take another 100gr of the same powder,and pile it into as small of a pile as you can.Light an oxy-acetylene torch with a large tip and quickly hold the torch flame right over the powder.Notice how much quicker it burns when it is concentrated together and has a much more powerful ignition source that can ignite much more of it at once.
When ignited in an unconfined state, smokeless powder burns inefficiently with an orange colored flame. It produces a considerable amount of light brown noxious smelling smoke. It leaves a residue of ash and partially burned powder. THE FLAME IS HOT ENOUGH TO CAUSE SEVERE BURNS.
The opposite is true when it burns under pressure as in a cartridge fired in a gun. Then it produces very little smoke, a small glow, and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure.
The opposite is true when it burns under pressure as in a cartridge fired in a gun. Then it produces very little smoke, a small glow, and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure.
Right after you straighten out the engineers at Cat you can call Accurate Powder and get them to correct their description of Properties of Smokeless Powders as well.
Here is the link below. You might pick up a thing or two from thisbut I have my doubts.
http://www.accuratepowder.com/props.htm
04-07-2009 | 05:00 PM
#32
Giant Nontypical
Joined: Feb 2003
Posts: 5,667
Likes: 0
From: fort mcmurray alberta canada
RE: 308 accuracy load
When ignited in an unconfined state, smokeless powder burns inefficiently with an orange colored flame. It produces a considerable amount of light brown noxious smelling smoke. It leaves a residue of ash and partially burned powder. THE FLAME IS HOT ENOUGH TO CAUSE SEVERE BURNS.
The opposite is true when it burns under pressure as in a cartridge fired in a gun. Then it produces very little smoke, a small glow, and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure.
The opposite is true when it burns under pressure as in a cartridge fired in a gun. Then it produces very little smoke, a small glow, and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure.
As to the effect of using magnum primers,primers are a controlled burn rate explosive just like powder,and as such going to a hotter primer has the same effect as adding more powder.I still feel that this is why the chamber pressure increases when magnum primers are used.It only makes sense that adding extra energy in the form of a more powerful primer, that in turn increases the temperature will increase the pressure.Increasing the temperature in a given volume will always increase the pressure.Does the burning rate of the powder increase significantly and does this have an effect on raising the chamber pressure significantly more?That has yet to be proven.Until it is either proven or disproven,you will have your theory,and I will have mine.
04-09-2009 | 11:08 AM
#33
Typical Buck
Joined: Jun 2005
Posts: 604
Likes: 0
RE: 308 accuracy load
And that I will accept as fact that powder burning under pressure burns at a faster rate.
Now there is the matter of at which pressures the burning rate increases,and how much it increases.The warning you quoted does not specify this.Does it increase from say atmospheric pressure to say 10000psi,or does it keep on increasing as the pressure increases.Does it increase significantly,or even measurably from say 55000psi to 62,000psi where a 308win operates.That is as of yet unproven.
As to the effect of using magnum primers,primers are a controlled burn rate explosive just like powder,and as such going to a hotter primer has the same effect as adding more powder.I still feel that this is why the chamber pressure increases when magnum primers are used.It only makes sense that adding extra energy in the form of a more powerful primer, that in turn increases the temperature will increase the pressure.Increasing the temperature in a given volume will always increase the pressure.Does the burning rate of the powder increase significantly and does this have an effect on raising the chamber pressure significantly more?That has yet to be proven.Until it is either proven or disproven,you will have your theory,and I will have mine.
As to the effect of using magnum primers,primers are a controlled burn rate explosive just like powder,and as such going to a hotter primer has the same effect as adding more powder.I still feel that this is why the chamber pressure increases when magnum primers are used.It only makes sense that adding extra energy in the form of a more powerful primer, that in turn increases the temperature will increase the pressure.Increasing the temperature in a given volume will always increase the pressure.Does the burning rate of the powder increase significantly and does this have an effect on raising the chamber pressure significantly more?That has yet to be proven.Until it is either proven or disproven,you will have your theory,and I will have mine.
04-27-2009 | 01:25 PM
#34
Guest
Posts: n/a
RE: 308 accuracy load
In response to the OP. Look up the 'Ladder Method' of load development. I have used it to good measure with a couple of the more accurate rifles I've owned, one of them being a Remington 700VLS .308. Once you get some points to play with from shooting the 'ladder', experimentation can and will produce some very accurate, and very consistant loads.
BTW, my most accurate .308 load was a Sierra 168 Matchking just barely kissing the lands, over a near max charge of Varget and Fed210M's in neck sized Lapua Brass. I got that load to shoot in the .4's (5shot) on a calm afternoon.
BTW, my most accurate .308 load was a Sierra 168 Matchking just barely kissing the lands, over a near max charge of Varget and Fed210M's in neck sized Lapua Brass. I got that load to shoot in the .4's (5shot) on a calm afternoon.
05-13-2009 | 07:00 PM
#35
Fork Horn
Joined: Jan 2008
Posts: 178
Likes: 0
From: kentucky
RE: 308 accuracy load
I am getting ready to start working a load up for my remington 788 in .308 for 150 gr. sierra spitzer flat base myself with varget powder will let you know the results. I have had great success with this powder and ct. 150 gr. bullets.
chris
chris
05-20-2009 | 08:10 PM
#36
Joined: May 2009
Posts: 2
Likes: 0
RE: 308 accuracy load
Magnum primers work best with spherical powders. I recently loaded some Sierra 150 gr FMJ Gamekings over 43grs of AA2230 @ 2.275 COAL and they were very accurate. I prefer IMR 4895 over 168 Amax's with CCI LR primers but had 3k LRM's I need to use up. Just a thought.
