What powders for steel and HW13

[figgy]

Exactly this at the point where you go over the powders limit or change something it will go way over the average pressure stated or known. 

The spike term comes from the sharp rise in pressure from say 12000 psi at for example a 42 grain powder charge but go to 43 or 44 grains and goes to 18000 yet 40 grains would be down at 9 or 10000 it don’t go up incrementally. For arguments sake say every grain of powder gave you 250 psi we know it don’t work like that but for explanation,  so 250 psi per grain upto the optimum for that load and powder say 11000 then the extra grain gives you an extra 2500 psi. Giving the so called spike in pressure. 

Hope that clears up the meaning as I understand it behind the term 

[cash1]

On 19/12/2017 at 17:12, cash1 said:

Do you chaps drop the powder charge by volume or weight? 

Dave

Sorry to be a pain, but do you weigh each powder charge or go off the volume alone?

 

[lancer425]

3 hours ago, figgy said:

Exactly this at the point where you go over the powders limit or change something it will go way over the average pressure stated or known. 

The spike term comes from the sharp rise in pressure from say 12000 psi at for example a 42 grain powder charge but go to 43 or 44 grains and goes to 18000 yet 40 grains would be down at 9 or 10000 it don’t go up incrementally. For arguments sake say every grain of powder gave you 250 psi we know it don’t work like that but for explanation,  so 250 psi per grain upto the optimum for that load and powder say 11000 then the extra grain gives you an extra 2500 psi. Giving the so called spike in pressure. 

Hope that clears up the meaning as I understand it behind the term 

There is no set point at which  spikes or sudden rises in pressure  if you like can occur, hence the importance of using published or tested data you know is suitable.

Some loads using Alliant steel for example here by their very nature will  be less prone to these rises, light loads generally are more forgiving .

 Yet even with these  light loads if you go for the high speed  loads which use relatively large powder charges, slight changes in component design or substitution of no longer available components in a load need careful consideration.

And if you take changes in the powders themselves as in A steel,  you have the potential for complications. With the more moderate loads like say a 10bore 1 3/8 oz at around 1500fps load you wont see any sudden jumps in pressure .

 But once you start looking for velocity or greater shot weight. the potential for these jumps is more prevalent.

 Looking at a reloading manual picking a load , be aware that deviation from the data in anyway can bump pressures up.

 The old rule of starting 10 %under on the powder charge is good advice, looking carefully for any signs of pressure before deciding or not as the case may be to use the full charge.

These precautions will help keep you safe as will researching yourself by testing loads, keeping a watchful eye on  components and any interchangeability or renaming .An example of this multimetal wads being dropped from production but TPS wads being a direct interchange as the had only detail differences in composition rather than physical differences.

Being vigilant is the best way of overcoming avoiding any complications which is far more important than getting the very last fps out of any published load, which may just have been developed years ago when load components could have been slightly different in characteristics only accurate testing will reveal how close to the data the load performs with components available today.

 

 

 

 

[Guest cookoff013]

the one point i have i went from a 24g steel load and put in 42g of powershot, and it only went up +400bar. thats not entirely a pressure spike. it went up, and varied alot. but never exceeded the MAP, but was a "bit wobbly" on statistics.

i dont really follow the rule, knock off 10% as its silly. no point knocking off 10% when the pressure is 7000psi. thats a lemon right there.

my criteria has changed over the years. first i find all data with that powder, with all weights of lead (example). the powder charges for these should be around a certain area, and i`ll pick the middle "powerband" and use the upper lead charge weights. this seems to extract alot more energy but be right in a linear range of pressures. it sounds like a lot of work for a simplified load, but the combination of larger lead shot weight and medium powdercharge nearly always puts lead in the 1200fps, and rock solid internal ballistics. (meaning, it takes nearly all the energy from the powder.) . when i did a lot of lead vs steel testing, the lead seems to get 500ftlbs more, probably because its denser and obviously larger payload charge, just sits there a microsecond more needing more energy to move, etc....

 

thats where i`m at now.

[lancer425]

8 hours ago, cookoff013 said:

the one point i have i went from a 24g steel load and put in 42g of powershot, and it only went up +400bar. thats not entirely a pressure spike. it went up, and varied alot. but never exceeded the MAP, but was a "bit wobbly" on statistics.

i dont really follow the rule, knock off 10% as its silly. no point knocking off 10% when the pressure is 7000psi. thats a lemon right there.

my criteria has changed over the years. first i find all data with that powder, with all weights of lead (example). the powder charges for these should be around a certain area, and i`ll pick the middle "powerband" and use the upper lead charge weights. this seems to extract alot more energy but be right in a linear range of pressures. it sounds like a lot of work for a simplified load, but the combination of larger lead shot weight and medium powdercharge nearly always puts lead in the 1200fps, and rock solid internal ballistics. (meaning, it takes nearly all the energy from the powder.) . when i did a lot of lead vs steel testing, the lead seems to get 500ftlbs more, probably because its denser and obviously larger payload charge, just sits there a microsecond more needing more energy to move, etc....

 

thats where i`m at now.

Powershot hw13 is denser so will generate lower pressures than steel will, so dependent what your 24g steel load was  a 7000psi is perfectly feasible in such a load.

And in a case such as this i agree reducing powder charge by 10% is not necessary, but at the start of paragraph 2 indeed throughout my post  i outline ALLIANT STEEL  and with typical available data A steel is generating more pressure than it did historicaly, and the 10% reduction in this typical data as example of such data  lets say RSI manual.

Where data has to change as not just the powder characteristics but winchester  stopped production  of primers used extensively in this data.

 And replacing these primers with the winchester replacements did alter the load characteristics.

In such cases with ALLIANT STEEL the 10% reduction in such circumstances is in my opinion prudent.