05-06-2022, 02:16 PM
Data consists of individual, observable or recordable facts or numbers or quantities, from whatever source. How "close to reality" or how trustable that Data is, is another question entirely.
And, to be fair to both "sides", while Hodgdon speaks of "slightly compressed," or "lightly compressed," [neither of which is really quantifiable by the way], and Klem speaks of "110%" compressed. Even Hodgdon would not recommend 110, I would bet a donut on that.
So in that respect the 2 positions are not really all that different. The crux of what the load might be lies in how much it actually was compressed for Alexander (let alone how much so for Redwood), vs what Klem (or other simulations) finds in their simulations.
I have some loads for my grendel modeled on Grt, and they are not Lapua brass, but dropping case volume/capacity down by 1 grain, loading in the 123 scenar to 2.265 OAL and 28.5 of varget comes up with 101.3% and 57ksi... which by definition would qualify as compressed, and above max.
So, from at least 5 different sources here, we have 5 pronouncements as to this "load"
1. Bill Alexander, unknown % case fill but marketable load at 28.5 (it might also be added that we may not know if AA is still loading this round at that load... sometimes lawyers have you back off to lower loads for liability reasons... )
2. Klem's QL model, which has it at 110% compression, 58 Ksi
3. My Grt which has a 101.3%, 57ksi
4. OP's load of unknown % fill/compression.
5. A5's load experiences, unknown pressures but 28.4-28.5 loaded out to 2.300" COAL. Somewhere at/above 100% fill give or take.
IF a load were at 110% compressed, THEN Klem's conclusions would rightly follow.
If compressed to say 102%, maybe not so dangerous/unpredictable but could still be overpressure. From my model, 27.7 gr is max pressure at 51.8 ksi, 98.5% load fill. Now this is a model, granted, but now you have this "datapoint" to consider.
The bottom line is that we seek a safe load from all perspectives. And Redwood, you might want to note that the Grendel does not exhibit overpressure indications in brass until you are way over. So lack of swipes and "rounded" or "unflat" primers, do not necessarily equate to being < 52 ksi.
And note that all of the above scenarios, except for OPs' are merely simulations or representations of his actual barrel-results, whether computer-program or "someone else's" barrel -- they are all "approximates," "estimations," of the OP. As we always say, ymmv.
Some clarifications from Redwood would be in order.
1. What OAL for the cartridge; did you work up to this or just plunge in at 28.5... and if worked up to, then what did the other results do. What kind of re-checks/re-torques did you do for the optics/mount, barrel install, etc. What kind of trigger does this rig have.
2. What kind of observation as to whether the load was not compressed, compressed, too compressed, or what.
3. Did you retest after removing the loose brake from the equation. ps, crush washers cause uneven torque on the muzzle, so use either an Accurate Washer system or jam nut or time it without crush washers...
3. What other loads/rounds have you shot from your rifle, what were the results.
4. What chrono results did your loads present.
5. Did you do a seating length test, varying the depth to see the differences in grouping.
6. 6.5 Grendel in an AR is better served with harder cup primers, like cci450, cc41's, Fed 205AR's. I don't think this would cause what you're seeing in grouping but it's a comment anyway.
And, to be fair to both "sides", while Hodgdon speaks of "slightly compressed," or "lightly compressed," [neither of which is really quantifiable by the way], and Klem speaks of "110%" compressed. Even Hodgdon would not recommend 110, I would bet a donut on that.
So in that respect the 2 positions are not really all that different. The crux of what the load might be lies in how much it actually was compressed for Alexander (let alone how much so for Redwood), vs what Klem (or other simulations) finds in their simulations.
I have some loads for my grendel modeled on Grt, and they are not Lapua brass, but dropping case volume/capacity down by 1 grain, loading in the 123 scenar to 2.265 OAL and 28.5 of varget comes up with 101.3% and 57ksi... which by definition would qualify as compressed, and above max.
So, from at least 5 different sources here, we have 5 pronouncements as to this "load"
1. Bill Alexander, unknown % case fill but marketable load at 28.5 (it might also be added that we may not know if AA is still loading this round at that load... sometimes lawyers have you back off to lower loads for liability reasons... )
2. Klem's QL model, which has it at 110% compression, 58 Ksi
3. My Grt which has a 101.3%, 57ksi
4. OP's load of unknown % fill/compression.
5. A5's load experiences, unknown pressures but 28.4-28.5 loaded out to 2.300" COAL. Somewhere at/above 100% fill give or take.
IF a load were at 110% compressed, THEN Klem's conclusions would rightly follow.
If compressed to say 102%, maybe not so dangerous/unpredictable but could still be overpressure. From my model, 27.7 gr is max pressure at 51.8 ksi, 98.5% load fill. Now this is a model, granted, but now you have this "datapoint" to consider.
The bottom line is that we seek a safe load from all perspectives. And Redwood, you might want to note that the Grendel does not exhibit overpressure indications in brass until you are way over. So lack of swipes and "rounded" or "unflat" primers, do not necessarily equate to being < 52 ksi.
And note that all of the above scenarios, except for OPs' are merely simulations or representations of his actual barrel-results, whether computer-program or "someone else's" barrel -- they are all "approximates," "estimations," of the OP. As we always say, ymmv.
Some clarifications from Redwood would be in order.
1. What OAL for the cartridge; did you work up to this or just plunge in at 28.5... and if worked up to, then what did the other results do. What kind of re-checks/re-torques did you do for the optics/mount, barrel install, etc. What kind of trigger does this rig have.
2. What kind of observation as to whether the load was not compressed, compressed, too compressed, or what.
3. Did you retest after removing the loose brake from the equation. ps, crush washers cause uneven torque on the muzzle, so use either an Accurate Washer system or jam nut or time it without crush washers...
3. What other loads/rounds have you shot from your rifle, what were the results.
4. What chrono results did your loads present.
5. Did you do a seating length test, varying the depth to see the differences in grouping.
6. 6.5 Grendel in an AR is better served with harder cup primers, like cci450, cc41's, Fed 205AR's. I don't think this would cause what you're seeing in grouping but it's a comment anyway.
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