Opened up my Richard Lee 2nd edition reloading manual to look at shoulder angles and case capacities of a could cartridges this morning and got sidetrack comparing ballistics of a couple established 7mm cartridges; 284 Win and 7 WSM. Looking strictly at a 175 gr bullet, the 284 Win takes 52 gr of Win760 to hit 2722 fps and 54548 PSI with a useful capacity of 3.97 cc. The 7 WSM uses the same 52 gr of Win760 to reach 2636 fps at 61,300 psi from a 5.02 cc useful case capacity.
I got sidetracked because I’m somewhat annoyed with the data we’re offered from reloading manuals as well as factory ammo from Hornady enough so that I’m actively pondering using my 7 PRC barrel as a tomato stake and spinning something on the rifle that’s actually capable of reaching the book velocity and expected accuracy.
Still trying to figure that out. The Hodgdon website parallels the data in the Hornady and Lee manuals for what was available at the time, though the Lee manual was originally printed in 2011 so I wouldn’t expect it to have any PRC or Weatherby RPM data based on that. It’s just interesting that those older cartridges are getting the same real world speeds with less powder and recoil than some of the latest heavily marketed rounds. Whatever the deal is with 7 PRC specifically, I’d really like to figure it out. Otherwise, a fast twist 7 Mag barrel might just find its was onto my PH3.
I jumped on the 7prc train early, probably too early. I developed a hand load, and this was only my third ever cartridge loading for with only a year or so experience hand loading in general. I chose the 168 LRX and at that time only Hodgdon had any reloading data. I went up to their Max charge and found a nice accurate load but definitely was not super happy with the low velocities out of my Seekins Element 21 inch.
Many, many months later Barnes released their own load data and had a significantly higher Max load for the powder I was using. So I started creeping up and got some extra velocity but then ran into a wall because this particular bullet loves a lot of jump in my rifle and I was getting compressed loads before I could get to the max listed by Barnes.
Have toyed around with doing some experimenting with VV powders, but, to be perfectly honest, I’ve been perfectly happy with the results I’ve seen out of my rifle with both the factory load of the 160 lrx, as well as the Federal loading of the 175 ELDX.
That 160 loading outperforms my 168 both in terms of raw velocity, as well as significant better ballistics.
I think some new cartridges are hype and marketing. 7 prc is a good cartridge but it really isn’t doing anything new. The 7 rem mag with an updated twist rate and seating the newer long for caliber projectiles out further you can do everything the 7 prc does. Compared to the 7 rem mag the main benefit of the 7 prc is overall length is shorter so you wouldn’t potentially have to single feed handloads. In terms of efficiency, you already have efficient 7 short mags in the rsaum and wsm. On a long or medium action, with a long freebore with the wsm or rsaum or the 7 SAUM wildcats, you can basically do what the 7 prc does but more efficiently. I think if you want an off the shelf rifle and off the shelf ammo, you’re good to go with the 7 prc or 7 rem mag. In fact you have more options with the 7 rem mag. But if you have the ability to reload and can get a custom barrel, then it’s more of a choose your own adventure. Any of them will get the job done.