Vapodog,

I have only been involved in reloading for ~ 20 years, but the truth is reloading has little to do with internal ballistics and more to do with following "cook book" instructions published in reloading manuals.

Now

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I've been reloading for over forty years and the term....."feet per second per grain of powder" has literally no meaning to me. Further to assert that velocity is somehow linear to powder used is a new concept to me.

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It is a common to use the energy per grain of powder for a given load. It isn't linear, that is true. However, for relatively small differences in powder charge, say 10%, the relationship is VERY NEARLY LINEAR. Powder energy per grain varies exponentially between, for common rifle propellants, 1.1 to 1.3 order. Linear is a 1 order exponential equation, so powder energy per grain AIN'T off by much.

Now I can literally post DOZENS of loads chronographed and with powder charges weighed to a 0.1 grain to support the VERY nearly linear relationship between powder charge, velocity, and pressure.

Of the discussion going on between Alf and Mike375, I would say that Alf is FAR closer to understanding the internal ballistics than is Mike. Mike is simply regurgitating the generic data relating pressure, powder charge weight, and velocity, which has been published for decades and is standard SAAMI doctrine of "safe" (read non-technical) reloading.

I can tell you right now that IMR4831 isn't the optimum powder for a 404 Jeffery, IMR4350 is a far better choice, and even that isn't optimum. I won't go any further because it would get too technical and this place CERTAINLY ain't the locale for technical discussions!!!

ASS_CLOWN

Mike, Thanks for the corroborating evidence that you provided above. I also agree completely about the hazard posed in a warmer climate. FWIW, my "case blow up" occured at 0 deg C (32 deg F). I am so glad it didn't happen on my subsequent trip to RSA!

Cheers,
Canuck

Alf

I agree with lawndart in that Reimington was trying to reach a little too far with their 400 Swift load, at least the lot I have. Except for the rare occasion when I have the time to drag all the computer crap to the range, the vast majority of testing is done indoors (~70 degrees F). I certainly wouldn't want to leave a box of those on the dash of a Land Rover and allow them to stew in their own juices, for a few hours. Then again, it just may be my rifle. It is one of the few that I haven't slugged although the chamber is just from a standard (not SAAMI min spec) reamer.

This is not rocket science, if something is loaded right on the ragged edge, it doesn't take much to push it over. I'd rather take something in the low to mid 50Kpsi range and have some cushion before things (literally) got sticky.

Mike