Home Forums Hunting & Shooting Hunter's Campfire Cartridge Progress

If we drop back from 60,000 lb/sq in. to the much milder 50,000 lb/sq in. in the .30-06 with the 168-grain Sierra HPBT, for example, we don't lose very much in velocity or energy � from 3,041 ft/sec to 2,887 ft/sec (154 ft/sec less) and from 3,446 ft-lb to 3,109 ft-lb (337 ft-lb less).

By dropping back to 83.3% pressure, we drop back to 95% muzzle velocity and 90% energy. And these down-range differences diminish appreciably with the distance that the bullet travels. (Looking at it through the other end of the scope, we see that boosting the pressure doesn't buy us all that much in velocity and energy.)

Also, a bullet with a higher ballistic coefficient further reduces the down-range deterioration by "bucking" the drag more efficiently.

Swedish and some of the German steels used by Lowe of the turn of the last century were just as good as anything now....overall tolerances are better, or atleast much easier to hold, but quality of materials really isnt all than much better....

This is turning out to be a typical mixed-up Campfire thread, for more than one reason:

1) Modern high-BC bullets (commonly called VLD for Very Low Drag) do NOT lose more velocity when pushed faster. Instead the BC actually increases slightly at higher velocities.

2) Lower pressure doesn't necessarily result in more accuracy. It often used to, so much that "load under max" was common advice. But that advice began back when many powders, such as IMR4895, were designed to burn most consistently at less than 60,000 psi. Most of today's centerfire rifle powders are designed to burn most consistently at 60,000 psi or so.

3) If lower pressures resulted in greater accuracy, then benchrest shooters would be loading to 50,000 psi. They don't.
In fact they normally load to over 60,000 psi.

4) Pressure isn't the main cause of barrel erosion. If pressure was the cause, the .308 Winchester would erodes barrels as quickly as the .300 Weatherby. Instead heat's the main culprit, and the greater the powder charge, the longer heat erodes steel on each shot. The easiest way to lessen heat duration is to use less powder, not more powder at lower pressures, one reason smaller cases are becoming more popular for longer-range shooting. (The other, of course, is VLD bullets that don't slow down faster when pushed faster.)

Now I'm ascared.

deflave and deBrent are agreeing!

Thanks for the education. Looks like something interesting to investigate that I've ignored at my peril, now to try to find the time. Never imagined BC could increase to that extent given the practical constraints of bullet design.

It appears as if Mr. Ackley did us all a great dis-service with all his fooling around with cartridges.

Should we dig Mr. Weatherby up and burn him at the stake?

And that foreigner, Lazzerini, or some such.......... you can tell by the name he was up to no good.

Pressure isn't the main cause of barrel erosion. � heat's the main culprit, and the greater the powder charge, the longer heat erodes steel on each shot.

Sshh, don't tell Ken - but you can still load it to 65 kpsi if you want and it will embarrass a laser beam.

What case is the 220 howell based on?

You gots to be a doctor or dumber to disagree with my logic.


Travis

Happens all the time. You just don't pay attention

Haven't read the whole thread, but I think the .220 Howell is a pretty interesting cartridge. And it looks like you can load it to 50ksi and still have the case full of powder, depending on what powder is selected.

Not real sure if you can do the same with a 7 mag or .300 win mag, let alone one of the Ultras. And I just don't like the idea of air space in the case when running a big boomer.