TEXASforLIFE
Ronin
For those who reload and not might know or know where too find accurate information. Trying to keep as equal as possible.
1. Max pressure at 60k
2. 24" barrel
3. Cartridge over all length
(2.800" example)
4. Same powder ( IMR4895 example)
5. Twist rate doesn't apply
6. Same caliber
7. Shoulder angle
As case volume increases, so does pressure. With larger case at the same pressure the case capacity/percentage changes. Max pressure is reached close to the throat or just past contact with the lands wouldn't/shouldn't cartridges of the same caliber have the same velocity? Well we know it ain't going to happen! Some cartridges can be close in velocity, but can vary 200 to 500fps. Whether it be short action with a .378" bolt face, .588" bolt face, short or long action why does this happen? I've done web searching and have found no credible/accurate to my liking information! My best theory is like the difference between natural gas and propane. Where NG is based on volume and propane is more pressure. Pressure gives it a good start, but can run short as distance increases. NG doesn't have a great start, but maintains volume as distance increases. There is a line where both will intersect, but that's where it changes. In a pistol using Unique for those 45acp fans it doesn't take much for a 230gr bullet to launch. Twist rate will have some affect, but lets leave that out. SIG with their 277fury had to up the pressure for a heavier bullet with the same case capacity too reach higher velocities in a shorter barrel (makes sense). For those crazy wildcatters using a 50bmg and necking it down to a 22cal..... well that's just more than crazy? Like the AI cases you don't gain much at the same pressure. Having a 6.5CM and a 260rem and barrels of the same lengths I'll try to do some testing (no idea when) and maybe shed some light on the subject? Reload manuals can be misleading due too favoritism (my thoughts)? I will work up loads using the x amount off the lands with above specified guide for velocity test, not accuracy. Maybe I think too much or not enough? I might need to give up "what about this or what about that" thinking? Is it OCPD? I hope not
?
1. Max pressure at 60k
2. 24" barrel
3. Cartridge over all length
(2.800" example)
4. Same powder ( IMR4895 example)
5. Twist rate doesn't apply
6. Same caliber
7. Shoulder angle
As case volume increases, so does pressure. With larger case at the same pressure the case capacity/percentage changes. Max pressure is reached close to the throat or just past contact with the lands wouldn't/shouldn't cartridges of the same caliber have the same velocity? Well we know it ain't going to happen! Some cartridges can be close in velocity, but can vary 200 to 500fps. Whether it be short action with a .378" bolt face, .588" bolt face, short or long action why does this happen? I've done web searching and have found no credible/accurate to my liking information! My best theory is like the difference between natural gas and propane. Where NG is based on volume and propane is more pressure. Pressure gives it a good start, but can run short as distance increases. NG doesn't have a great start, but maintains volume as distance increases. There is a line where both will intersect, but that's where it changes. In a pistol using Unique for those 45acp fans it doesn't take much for a 230gr bullet to launch. Twist rate will have some affect, but lets leave that out. SIG with their 277fury had to up the pressure for a heavier bullet with the same case capacity too reach higher velocities in a shorter barrel (makes sense). For those crazy wildcatters using a 50bmg and necking it down to a 22cal..... well that's just more than crazy? Like the AI cases you don't gain much at the same pressure. Having a 6.5CM and a 260rem and barrels of the same lengths I'll try to do some testing (no idea when) and maybe shed some light on the subject? Reload manuals can be misleading due too favoritism (my thoughts)? I will work up loads using the x amount off the lands with above specified guide for velocity test, not accuracy. Maybe I think too much or not enough? I might need to give up "what about this or what about that" thinking? Is it OCPD? I hope not
?
sorry had to do it 