I saw a post about whether doing reduced recoil loads for a 7mm PRC would be feasible, so I figured I would do a quick write up about my thoughts on it since I have been spending a lot of time working out some hypothetical reduced loads for a few different calibers. Most recently was the 27 Nosler, which is another relatively new cartridge without widespread adoption.
The case capacity of the 7mm PRC is somewhere between a 7mm Rem Mag and a 7mm SAUM in case capacity, so we can look at load data for those two and roughly extrapolate some places to start with reduced loads.
The Lee 2nd Edition Modern Reloading book has load data for the 7mm SAUM for H4895 for 100, 110, and 115 projectiles with starting loads of 53gr on the 100 & 110 and 51gr on the 115. For the 7mm Rem Mag, based on Quick Load data, starting load for a 110gr is about 54gr. So with the 7mm PRC, somewhere around 54gr is probably a fine starting point, and will get about 3,100 fps in a 24″ barrel. That will put the recoil around 16-18 ft-lb of energy with a 7lb rifle.
In addition to the data from Lee, there was an article in an older edition of the Hodgdon manual about reduced loads, (MELs – Moderate Effective Loads), which has the 7mm Rem Mag reduced loads with a 120gr Barnes TTSX loads for H4895, H4198, IMR4895, and IMR4198 at 49.3gr, 42.3gr, 48.3gr, and 41.8gr respectively. These are pushing between 2,850-3,000fps with 10-11ft-lbs of energy and those same charges, plus 1grain would probably be fine with the 7mm PRC. Hodgdon also has their cheat sheet for reduced loads for H4895 that is a good reference.
Circling back to the Modern Reloading, Chapter 9 & Chapter 10 has the how to for their 1 grain pressure and velocity factoring table and there is plenty of data in there on other bullets that would serve as a starting point.
One final resource is the Lyman Cast Bullet Handbook. This also has data for the 7mm Rem Mag for loads for cast boolits in 119gr, 135gr, 150gr, and 162gr for powders such as Red Dot, IMR4198 and H4895. These have some really low pressures, down in the 25,000 – 32,000 C.U.P.
So with that, hopefully this provides some places for others to explore further in their quest for reduced recoil loads for the 7mm PRC.