PSI per gr

[smokepolehall]

How low n high fer consistant ignition in a 45 cal ?

[smokepolehall]

Ok how low can the psi be n still ignite the load in cold Temps ?

[joelmoney]

So if I get this correct you want to know what the lowest powder charge of H4198 that will launch your smooth formed bullet out your barrel? If in fact that is your question I don’t think you are going to get accuracy until you kick the bullet hard enough to get it to swell. I had my questions about 209 ignition in cold weather. I would look at going with a tight fitting sabot if I wanted low velocity. I think there are better powder choices for lower velocity loads and better cold weather ignition. Since I don’t shoot 209 I’ll pass on calling those powders out by name.

[smokepolehall]

Thank you, i know the 3 faster powders i have will have no trouble firing. VV110 / 4759 n 5744. So if'en i am doubt i can just duplex my H4198 n RL7

[ET]

Apr 18, 2019 6:54:25 GMT -5 smokepolehall said:

Ok how low can the psi be n still ignite the load in cold Temps ?

I don’t believe you can view PSI per grain as a linear relationship. If that were true then I could take a load of 40grains that produces 40K and add 25% more powder to get 50K. I DON’T THINK SO.
When powder begins to burn it builds pressure that begins to accelerate the burn producing more pressure quickly.
The initial start of the powder burn is affected by colder temps and can be offset with an extra grain of powder or two to get the start of the burn pressure equal to the burn at warmer temp.

From my limited understanding powder burn rates are designed to respond to specific load resistance and bore volumetric expansion as bullet is propelled forward. From my perspective the amount of powder used must not exceed producing more pressure than what is desired for a given application. In other word’s the fuel source needs to deplete at a given pressure level to stop it from further build up.

IMO what governs ignition are 3-factors.
1) Load resistance and volumetric expansion
2) Choice of powder with specific burn rate
3) Intensity of ignition source.