Printable View
Having a hard time finding any load info for lupua 185gr scenar .308 bullets with IMR 4064 powder. Lupua doesnt offer it on there site, only load data for vihnt V powder and Its hard to come by. Does anybody have any manual that has load info for these bullets and powders other than vihnt V? My go to load uses 4064 and have lots of It. Any help would be much appreciated.
I would start with loads for the 190gr bullets and work up from there.
Yea was kind of thinking about 40gr of 4064 would be a good place to start.
Every manual I’ve ever read states that if no data exists for the weight bullet being used then data from the next heaviest bullet can be used to start and proceed with load development
For a .308 with a 24 inch barrel at SAAMI recommended O.A.L. of 2.800 and trim length of 2.005 at 70 deg F.. QuickLOAD shows the max charge for IMR4064 with a 185 Scenar is 42.3 grains and a mv of 2625 fps with a pressure of 61,930 psi. PMax for a .308 is 62,000. The mv numbers change if the barrel is shorter or longer but the pressure stays the same.
QuickLOAD is usually conservative.
Changing seating depth will change the pressure. Seating the bullet deeper, increases the pressure and seating it out into the chamber decreases the pressure, about 5 fps per 0.010 and an O.A.L. of 2.8010 with trim at 2.005 at 70 degrees drops pressure by 500 fps.
It is just the opposite effect for changing trim length, about 2 fps per 0.010 but changing trim length from 2.005 to 2.010 at 70 degrees with O.A.L. at 2.800 puts to pressure over PMax.
I would still recommend that you start 10% lower than the max load and work up watching for pressure signs.
Barrels often have differences in chamber specs depending on the amount of use the reamer may have had before it got to your barrel, so pressure can be quite different.
I had one barrel that was quite tight and I got high pressure signs even with minimum loads. Savage bored the chamber out a few thousandths and the problem went away. Interestingly, the accuracy was no different after the correction.
If you are shooting at around 50 deg. F., the pressure will drop to just under 60,000 with a velocity of 2603 fps so if you don't try to push the limits on velocity, you should be in a reasonable range.
2013 In case anybody is wondering.
That's backwards.Quote:
Originally Posted by CFJunkie
QL had an error at one point where it did show that to be the case, linearly; which is incorrect.
The deeper you go, the system pressure drops due to gas escaping around the bullet which hasn't engraved and sealed in the lands. There is a point of depth where burning rates are sufficiently changed that yes, the pressure does spike; but those are silly depths, and easily confirmed by actually measuring pressures rather than calculating them.
Also be careful with QL assumptions about 4064. They are presuming the old formula prior to a complete revamp of that plant, roughly a couple years ago. Also doesn't account for the 8# jugs that Hodgdon quietly sourced from Rhinemetal during that time period.
darker,
I think that QL and I agree with you since I clearly said "seating it out into the chamber decreases the pressure, about 5 fps per 0.010".
That is not backwards and it agrees with your statement, although leakage isn't the only reason the pressure drops. The volume available for gas expansion is greater as well. Both cause the pressure to decrease.
I also said that seating deeper into the case increases the pressure, restricting the volume between the bullet and the powder at ignition which causes the pressure to rise.
That too is correct and I didn't say pressure spiked.
Of course, if you jam the bullet into the rifling, there is a significant pressure spike, much higher than moving the bullet a few thousandths into or out of the brass, but I wasn't referring to jamming the bullet into the rifling.
Quote:
Originally Posted by CFJunkie
Quote:
Originally Posted by CFJunkie
?? What dakker typed is opposite of what you are saying. But i agree with your statements. Berger bullets states same thing
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long.
Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.