Well said, Saeed.

Bren: I can attest to the significant difference between original surplus 4831 (ALL of which I have found to be rather consistent from lot to lot) and the later, and much faster) IMR 4831 (current "H-4831" is also some bit faster, but not as fast as the IMR version). In my many years of using vast quantities of Surplus 4831 (still have 20 pounds!) in calibers ranging from .243 to .338, I have found that it is actually much closer to current IMR 7828, being on average about 1 "grain" faster in a typical load (example: Surplus 4831 might require 50 grains for a given velocity whereas IMR 7828 might use 51 grains for a similar velocity at a similar pressure).

A ratio of 60 or 61 grains of IMR 4831 to about 65 grains of Surplus 4831 would seem about right (each yielding the about the same pressure, while the Surplus would likely yield a bit more velocity in cases where the powder speed was properly matched to the expansion ratio.)

BTW, I had a friend who wanted to build a custom .25-06 back in 1969 -- this was when the .25-06 was still a wildcat. The gunsmith refused and recommended a .25-284 instead, due to the fact that custom .25-06's were infamous for unexplained blow ups. In tracing down the source of this "bad" reputation for the .25-06 we found that the common thread was that most new owners used the most widely available and appropriate powder -- Surplus 4831 -- and tended to be extremely conservative in starting loads for their new custom guns. The result appears to have been a inordinate number of S.E.E. occurances due to low loading densities, thus the negative reputation and resulting refusal of some smiths to chamber the .25-06.

thanx much guys, excellent stuff,
Got a blown ML by Savage that is rocking the smokeless world. This Secondary explosion effect looks to be the cause to me.. Doc Stone

"...If only Elmer Keith were here, he'd have the answer for us on the spot..."

Yeah, and the answer would most probably be wrong too.

Now before anyone jumps on me about Elmer, he was one of my favorite gun writers - only second after Jack O'Connor. But, many things he wrote were like Swiss cheese - full of holes.

Back to the subject at hand.

I have tried to find any sort of proof of how and why this SEE happens, but I am afraid so far I have drawn a blank.

I did this for self preservation, as we do load for an awful lot of different cartridges here, and we certainly do not wish to add to our problems.

We do have Walter to contend one, and I can assure you, that is more than enough trouble to have in the workshop.

Lots of articles have been written about it, but none was about it being done under controlled conditions, and repeatable.

We load quite a bit of reduced loads in the larger caliber rifles - up to the 577 T.Rex. And I usually use a pistol powder, like Green Dot, UNIQUE and many others.

Sometimes we actually use re-claimed powder from shotgun shelss.

And so far we have had no problems whatsoever.

I am surprised of the mention of IMR 3031 as being the cause of a rifle blow up. As my understanding was that SEE was only likely to happen when one uses very slow burning powders, rather than medium ones like IMR 3031.

Having said that, I think there have been enough accidents attributed to SEE, that we all should be careful of trying to load a reduced charge of rifle powder in any caliber.

If one wishes to have a reduced load, then one should use suitable powders for it.