04-12-2023, 05:58 PM
thank you Zen for the data so far.
some open conjecture here, so take with a grain of salt: I think, based upon my experiences in reloading for the last 50 years, that ball powders need to be near the upper pressures for low SD of MV. Stick powders are a bit more tolerant. Flake powders the most tolerant. So far, in pursuit of low SD in MV, it is my experience to date in quite a few cartridges that go up to ~60K psi or so that the MV SD reduces as I have crept up on max loads. Typically, though not always due to other effects, low SD also gives better groups as well. and for the long range F-class shooters, low SDs correlate to less vertical stringing and more X's
Since the max pressure spec of the 6.5 Grendel is down from the more mainstream cartridges, my hypothesis is that the ball powders are not getting enough pressure for consistent burn rates, though your SD numbers with the 123s look great. But notice that as the powder charge is increasing, the SDs are decreasing.
if I recall, the Hodgdon burn rate manual shows staBALL match at a faster burn rate than CFE223. So, like you, I'd expect better performance in the Grendel with staBALL match than CFE223.
I've had really good performance, to my mind, with H4895, and that may be due to it is a bit easier to ignite, based upon what I've read, than ball powders are. My assumption is that it burns more consistently due to easier ignition at lower pressures than ball powders would at the same pressure due to the tougher to ignite characteristics of ball powders, in general.
as an aside, I think for awhile, we're at the mercy of the powder manufacturers and will just have to utilize what we can get rather than what we really want. And for now, it appears that Winchester is able to supply ball powders where as IMR and ADI (Hodgdon's extreme series) are not, or don't seem to be, interested in meeting the increased demand. In fact it seems that IMR quit making the Enduron series of powders altogether. No one in my part of the country has seen Retumbo,Varget,H4895 for about 2 years now. So you are wise to experiment with staBALL match since it is available and is somewhat close to a useful burn rate for the Grendel.
thank you.
-tdbru
some open conjecture here, so take with a grain of salt: I think, based upon my experiences in reloading for the last 50 years, that ball powders need to be near the upper pressures for low SD of MV. Stick powders are a bit more tolerant. Flake powders the most tolerant. So far, in pursuit of low SD in MV, it is my experience to date in quite a few cartridges that go up to ~60K psi or so that the MV SD reduces as I have crept up on max loads. Typically, though not always due to other effects, low SD also gives better groups as well. and for the long range F-class shooters, low SDs correlate to less vertical stringing and more X's
Since the max pressure spec of the 6.5 Grendel is down from the more mainstream cartridges, my hypothesis is that the ball powders are not getting enough pressure for consistent burn rates, though your SD numbers with the 123s look great. But notice that as the powder charge is increasing, the SDs are decreasing.
if I recall, the Hodgdon burn rate manual shows staBALL match at a faster burn rate than CFE223. So, like you, I'd expect better performance in the Grendel with staBALL match than CFE223.
I've had really good performance, to my mind, with H4895, and that may be due to it is a bit easier to ignite, based upon what I've read, than ball powders are. My assumption is that it burns more consistently due to easier ignition at lower pressures than ball powders would at the same pressure due to the tougher to ignite characteristics of ball powders, in general.
as an aside, I think for awhile, we're at the mercy of the powder manufacturers and will just have to utilize what we can get rather than what we really want. And for now, it appears that Winchester is able to supply ball powders where as IMR and ADI (Hodgdon's extreme series) are not, or don't seem to be, interested in meeting the increased demand. In fact it seems that IMR quit making the Enduron series of powders altogether. No one in my part of the country has seen Retumbo,Varget,H4895 for about 2 years now. So you are wise to experiment with staBALL match since it is available and is somewhat close to a useful burn rate for the Grendel.
thank you.
-tdbru