- Thread starter Lance B
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Re: Compressed loads
No compressing your loads is not a terrible thing. If your gun likes it shoot it.
No compressing your loads is not a terrible thing. If your gun likes it shoot it.
Re: Compressed loads
Well, the higher the pressure at any given time, the faster the burn rate....thats for any powder.
The scale your talking of though is maybe just a pound per in. or so, which in the scheme of tens of thousands of PSI I couldnt see effecting the burn rate any noticable ammount.
Ofcourse, none of this is chemical.
Well, the higher the pressure at any given time, the faster the burn rate....thats for any powder.
The scale your talking of though is maybe just a pound per in. or so, which in the scheme of tens of thousands of PSI I couldnt see effecting the burn rate any noticable ammount.
Ofcourse, none of this is chemical.
Re: Compressed loads
Unless severly compressed in the way that the powder is physically deformed I wouldnt think that the chemical compostion will change. Some beleive that the "burn" can be more uniform due the powder not being able to shift around versus a load that doesnt take up the case.
Unless severly compressed in the way that the powder is physically deformed I wouldnt think that the chemical compostion will change. Some beleive that the "burn" can be more uniform due the powder not being able to shift around versus a load that doesnt take up the case.
Re: Compressed loads
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AI Shooter</div><div class="ubbcode-body">Does the compression of powder alter the chemical composition of the powder?</div></div>
You may be crushing off the retardants used to control the burn rate on 1%-3% of the powder granule edges. I would bet that the normal charge to charge has more energy variation than what you would get by crushing the corners off the granules.
So, in theory, you are changing the composition; however, in practice not be enough to even be measured.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AI Shooter</div><div class="ubbcode-body">Does the compression of powder alter the chemical composition of the powder?</div></div>
You may be crushing off the retardants used to control the burn rate on 1%-3% of the powder granule edges. I would bet that the normal charge to charge has more energy variation than what you would get by crushing the corners off the granules.
So, in theory, you are changing the composition; however, in practice not be enough to even be measured.
Re: Compressed loads
The only way you'll change the chemical composition of powder is by either burning it or subjecting it to a solvent. Now, relating to changing the burn rate:
Burn rate is a function of surface area and chemistry. You can't change the chemistry by loading density. However, you can affect ignition properties thru different loading densities. If you cram too much powder into a case, you'll alter how the primer transfers heat and particulate matter into the propellant bed. So the short answer: yes, changing loading density by compressing the propellant bed will affect ignition characteristics. Will you really get that much more performance out of the cartridge? Likely not. As you compress, you also increase the likelyhood of "ullage". The primer goes off and pressurizes the case. The bullet can indeed move forward before all the powder's ignited. You just drastically changed your boiler room. Now the powder's got to catch up, albeit in a much larger chamber. Not saying it happens all the time, but it certainly improves the chances of it happening...
The only way you'll change the chemical composition of powder is by either burning it or subjecting it to a solvent. Now, relating to changing the burn rate:
Burn rate is a function of surface area and chemistry. You can't change the chemistry by loading density. However, you can affect ignition properties thru different loading densities. If you cram too much powder into a case, you'll alter how the primer transfers heat and particulate matter into the propellant bed. So the short answer: yes, changing loading density by compressing the propellant bed will affect ignition characteristics. Will you really get that much more performance out of the cartridge? Likely not. As you compress, you also increase the likelyhood of "ullage". The primer goes off and pressurizes the case. The bullet can indeed move forward before all the powder's ignited. You just drastically changed your boiler room. Now the powder's got to catch up, albeit in a much larger chamber. Not saying it happens all the time, but it certainly improves the chances of it happening...
Re: Compressed loads
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1SMALLJOHNSON</div><div class="ubbcode-body">The only way you'll change the chemical composition of powder is by either burning it or subjecting it to a solvent. Now, relating to changing the burn rate:
Burn rate is a function of surface area and chemistry. You can't change the chemistry by loading density. </div></div>
Yes, taking the entire charge weight as a whole; almost, taking the granules individually.
The retardants are applied to the outsides of the granuels (to control burn rate*), It is the outsides of the granuels that interact with each other to cause the compressed condition. As the bulelt get seated ever deeper, the granules flake to relieve pressure. The retardants are on the surface yeilding to the stress applied by the seating bullet.
So, the absolute chemistry of the whole load is not different. However what remains in the granule itself has changed, since the retardant on the surface has flaked away. But as I said before; the effect is probably too small to even measure accurately enough to verify. So, for the average reloader, you might as well take the position that the chemistry does not change durring compression.
(*) other burn rate characteristics are embeded in the shapes of the granules themselves.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1SMALLJOHNSON</div><div class="ubbcode-body">The only way you'll change the chemical composition of powder is by either burning it or subjecting it to a solvent. Now, relating to changing the burn rate:
Burn rate is a function of surface area and chemistry. You can't change the chemistry by loading density. </div></div>
Yes, taking the entire charge weight as a whole; almost, taking the granules individually.
The retardants are applied to the outsides of the granuels (to control burn rate*), It is the outsides of the granuels that interact with each other to cause the compressed condition. As the bulelt get seated ever deeper, the granules flake to relieve pressure. The retardants are on the surface yeilding to the stress applied by the seating bullet.
So, the absolute chemistry of the whole load is not different. However what remains in the granule itself has changed, since the retardant on the surface has flaked away. But as I said before; the effect is probably too small to even measure accurately enough to verify. So, for the average reloader, you might as well take the position that the chemistry does not change durring compression.
(*) other burn rate characteristics are embeded in the shapes of the granules themselves.
Re: Compressed loads
Dog gone it. Chemistry does not change with compressed loads. If you're breaking the powder, you're changing geometry. Geometry affects burn rate to a large extent. Deterrents, when placed on the surface of propellant are glued or bonded to the surface. If they flake off during compression, they'd surely MORE flake off during manufacturing and shipping, and you'd find a whole heap of it at the bottom of your canisters. Check your premises.
Dog gone it. Chemistry does not change with compressed loads. If you're breaking the powder, you're changing geometry. Geometry affects burn rate to a large extent. Deterrents, when placed on the surface of propellant are glued or bonded to the surface. If they flake off during compression, they'd surely MORE flake off during manufacturing and shipping, and you'd find a whole heap of it at the bottom of your canisters. Check your premises.
Re: Compressed loads
The only thing you really have to worry about is how compressed the load is. In a HIGHLY compressed load, your seating depth can change overnight as the powder pushes the bullet out to where it can settle.
Experiment with it and see. I've seen as much as twenty thousandths.
The only thing you really have to worry about is how compressed the load is. In a HIGHLY compressed load, your seating depth can change overnight as the powder pushes the bullet out to where it can settle.
Experiment with it and see. I've seen as much as twenty thousandths.
Re: Compressed loads
Not only that, but propellant is a plastic. It expands and contracts according to heat. If you make a compressed load, better bring your lunch and work on crimping those rounds. Better have enough crimp pressure, or the bullet will a-come right out of the case.
Not only that, but propellant is a plastic. It expands and contracts according to heat. If you make a compressed load, better bring your lunch and work on crimping those rounds. Better have enough crimp pressure, or the bullet will a-come right out of the case.
