Any Ballisticians here? (Cartridge Pressure Discussion)

[Bullet Guy]

either the designers ego or billfold imho

If the ease of low velocity SDs holds up along eith with greater MV at safe pressures, I certainly can see a niche for this modification especially when applied to short action lengths. The parent case is one of the most efficient at imparting more bullet energy/grain of powder than the 300 WM or Weatherby. The 30 06 case is close to the 308Win. Now I’m talking 0.308 caliber. Whether that same efficiency holds for a smaller caliber, I can’t say.

 

[Dsrtibb]

Just wanted to correct a couple of inaccuracies, and then ask a question to any members of the forum who might have, and are using pressure equipment.

First of all, there is a 0.010 taper between the base and the shoulder diameters, so the case is tapered.

Secondly, the shoulder is not curved like Weatherby. What you are showing looks like a hydroformed case that has not been fired yet in a Moses chamber. Additionally, the neck length is about 0.125” long.

Just to set the stage a bit, there have been several thousands of these cases and similar 223 cases made with the Moses modification from the parent cases without a single serious overpressure incident. Also several of the shooters using Moses cases have use them in local matches. From the velocity data I have seen, it appears to me that single digit SDs are easier to obtain with these cartridges than the parent cartridges. I am having a 308 Moses barrel made to verify for myself the velocity SD issue. The Moses modification of the 308Win case seems to add capacity for approximately 7 grains of ball powder. How well this added capacity improves velocity is not clear to me, but clearly there is no replacement for displacement.

Finally, does anyone have real pressure measurements that one can solidly attribute to primer flattening, primer cratering and/or expandion of the primer pocket that would lead to a loose primer? That would clearly be of interest to all handloaders. Speculation on this point is worthless without real verifiable pressure measurements. If one doesn’t know then say so. If you have data lets see a pressure curve. It does nobody any good to bash this case modification by promoting inaccure facts and speculation not based on verifiable facts and measurements.

We have ran up to 59gr of Superformance in the 308 Moses pushing a 168gr eldm in 100° weather. Not one sign of pressure.... only thing we experienced was the barrel heating up pretty fast. The 7mm Moses won the unicorn challenge (1941yds) at the 2023 Nightforce ELR Match and had 2 other 7mm Moses rifles in the top 60 for individual. We had 5 moses rifles 4 7mm Moses and one 6.5 Moses (Youth) running at this 2 day match with again zero issues. The DMR ELR match in Preston ID was Aug 19th 2023 and the 7mm Moses with 180s took 1st, 2nd, and 5th place overall (1st and 2nd in open, 1st in Ladies, 1st in youth (6.5 moses) and 1st in the 1290yd timed challenge (5 shots in 32 sec, 4 of 5 impacts on a 10" plate)