Quick load help

[LRRPF52]

QL can be about 10,000-11,000psi higher than real world in this case when you see figures like 62,000-63,000psi for a load that’s only .5gr over published max, though 8208XBR is known to spike on you once you get near or over max published tested loads.

A lot of factory ammo manufacturers aren’t going to chase the 52,000psi MAP due to variance in MPSM (maximum Probable Sample Mean) and MPLM (Maximum Probable Lot Mean), so it’s better to hug that 49,500-50,500psi space where standard deviation in the samples won’t push over 52,000psi.

If you look at all of Hodgdon’s and Western Powders pressure tested data, you see a lot of max loads that stay well under 50,000psi due to case volume, but they can also be some of the fastest/most efficient load combinations due to the powder efficiency and balanced resistance from the particular projectile.

I also noticed that Hodgdon’s has newer data for 8208XBR under the 107gr SMK that is less than their previous data with that combo. All the components appear to be the same with Hornady case, Federal 205 primer. The previous data I’ve been familiar with all these years lists 29.8C gr under the 107gr SMK at 2,667fps and 49,300psi. The new data lists 28.7C at 2,740fps and 50,600 PSI.

Another bullet that can give us some clues as to where the pressure is, within a certain pressure range, is the 100gr Nosler Partition. The Partitions behave similarly to monoliths because they have a sectional wall inside of them that does not like being compressed, so they resist being driven into the lands and don’t have any bearing surface relief bands cut into them.



Hodgdon’s data for the 100gr Partition and 8208XBR: 28.7gr 2,790fps 50,400 PSI

One thing powder manufacturers will do if you look closely, is avoid pushing near the SAAMI MAP with monolithic bullets (like the 100gr TTSX), due to how they resist being driven into the lands more than cup and core bullets.



Pressure increments average higher as you increase charge weights, so when you mass-produce your lots of ammo, if you chase the maximum listed MAP, you will have more incidence of loads that go over the MAP.

The good thing with a 100gr TTSX is that they aren’t really long like many other monoliths, and they have bearing surface relief bands in them, so they work well with 8208XBR as long as you don’t exceed that maximum published charge weight.

If you have room to work with your COL without jamming the lands, it will help you a little as well.

If you run several ballpark muzzle velocities through a ballistics program, you’ll see that chasing the last .5gr of charge weight doesn’t really give you any practical performance advantage, so it makes sense to err on the side of prudence and stay under book max values for the given COLs.

Hopefully that helps.