02-15-2020, 06:09 PM
An extra 0.100" in case length (therefore also in chamber length since the horizontal cylinder of the case is longer), assuming the shoulder and neck dimensions don't change, would yield about 6.6% more available volume, by my back-of-envelope calculations. This leads to about +2 grs powder capacity.
Now we must assume a bolt action b/c an AR bolt limits us pretty much to the 52Ksi developed pressure... extra powder means extra pressure possible... so a bolt action can be made to handle that.
Also I would assume that the extra coal does not add a significant amount of performance (just less case-volume robbery by the bullet), this is of course a simplifying assumption.
What would an extra 2 grs of powder do to the developed MV? Using 123 gr Eld's/SSt's & CFE as an example (also 24" barrel), it adds about 160 ft/s to the final MV. I got the same theoretical increase with 2520. Since the case volume has been expanded I'm assuming that final pressure is still within limits.
Now all of this is without using QL, so when the QL experts chime in I will be interested in what they can advise.
Now we must assume a bolt action b/c an AR bolt limits us pretty much to the 52Ksi developed pressure... extra powder means extra pressure possible... so a bolt action can be made to handle that.
Also I would assume that the extra coal does not add a significant amount of performance (just less case-volume robbery by the bullet), this is of course a simplifying assumption.
What would an extra 2 grs of powder do to the developed MV? Using 123 gr Eld's/SSt's & CFE as an example (also 24" barrel), it adds about 160 ft/s to the final MV. I got the same theoretical increase with 2520. Since the case volume has been expanded I'm assuming that final pressure is still within limits.
Now all of this is without using QL, so when the QL experts chime in I will be interested in what they can advise.
"Down the floor, out the door, Go Brandon Go!!!!!"