Questions for the experts:
In my understanding, the factors (or combination of some of them) that influence how high pressure a cartridge is are:
- Powder quantity (obvious)
- Powder type
- Overbore ratio
- Case shape/design and case space/powder ratio
Am I missing something else? Is this correct?
I heard somewhere that in a very high pressure cartridge if you go below certain bulet weight you may actually decrease the velocity because the powder charge doesn't have the time to reach full pressure potential....true o fantasy?
Along the same line, it is a correct assumption that the shape of a bullet in any given cartridge may influence barrel speed because of variance in bearing surface? I heard also that a "too loose" bullet (very small bearing surface) may actually result in slower velocity because, again, the powder charge behind cannot reach peak value..true or false??
And if this is true (one or all of the instances) what are the difference in percentage? Negligible or noticeable?
Last point is this: We all know that you could have a higher pressure cartridge that may actually develop slower muzzle velocities than a lower pressure one even within the same caliber and bullet weight...I always assumed the difference would be that in the lower pressure cartridge, the powder charge would burn longer (because of quantity and/or powder characteristics and/or case design factors)....Am I correct?
A typical example is the comparison between 308 Winchester and 30-06 Springfield...the 308 is a higher pressure cartridge but it actually reaches slower muzzle velocities than the 30-06 (when both loaded to their full potential) even using the same identical bullet (weight and shape)....in this particular case why is so? What are the factors in play?
Thanks!!
Regards
In my understanding, the factors (or combination of some of them) that influence how high pressure a cartridge is are:
- Powder quantity (obvious)
- Powder type
- Overbore ratio
- Case shape/design and case space/powder ratio
Am I missing something else? Is this correct?
I heard somewhere that in a very high pressure cartridge if you go below certain bulet weight you may actually decrease the velocity because the powder charge doesn't have the time to reach full pressure potential....true o fantasy?
Along the same line, it is a correct assumption that the shape of a bullet in any given cartridge may influence barrel speed because of variance in bearing surface? I heard also that a "too loose" bullet (very small bearing surface) may actually result in slower velocity because, again, the powder charge behind cannot reach peak value..true or false??
And if this is true (one or all of the instances) what are the difference in percentage? Negligible or noticeable?
Last point is this: We all know that you could have a higher pressure cartridge that may actually develop slower muzzle velocities than a lower pressure one even within the same caliber and bullet weight...I always assumed the difference would be that in the lower pressure cartridge, the powder charge would burn longer (because of quantity and/or powder characteristics and/or case design factors)....Am I correct?
A typical example is the comparison between 308 Winchester and 30-06 Springfield...the 308 is a higher pressure cartridge but it actually reaches slower muzzle velocities than the 30-06 (when both loaded to their full potential) even using the same identical bullet (weight and shape)....in this particular case why is so? What are the factors in play?
Thanks!!
Regards
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