Hunteria,
The ringing in the barrels was not from using DACRON IMO, rather it was from using IMR-3031 powder with and without a filler as was a long time practice back in the good ole days! and your right there is and has been a lot of controversey on the subject of doubles.

The double rifle is shadowed in myth and misinformation such as IMR-4831 will split barrels or blow up guns from a double explosion, but I have never been able to varify that with anything but "well I know a guy" or "my uncle charley did it" etc. and I have tried for years to varify one proven case, no luck... Another myth that is simply hogwash is that you must shoot a double with the front trigger then the rear trigger (ritht left) as that is how it was regulated..I have done it both ways many times and there is no difference in any double I have ever shot and that is a bunch of double rifles..In fact I always shoot the rear trigger first, as on ocassion if you shoot the front one first then sooner or later your finger will come off the front trigger and hit the rear and you will get a double bang, and it will kick the liveing s---t out of you! smile I will also add that I have used the GS custom monolithics and North Fork monolithic bullets in about all of the English rifles and with no problems at all, and that is about all I use in the Searcys or modern guns. I have heard that the Barnes solids will split barrels, but I simply dont' believe it, but I won't swear to it because as sure as I did someone on this board would blow a gun up with them..probably because they over loaded it and blamed it on the bullets used, that's always real convienient, and grounds for a law suit and recovery of a expensive rifle I suspect! smile. Nice talking to you.

Mike1,
Yes, the 75% rule is what I used to come up with my 45 grs. of XMP-5744 load and a 500 gr. bullet in my .470 mentioned in my last post above..It does work 99% of the time and when it doesn't its usually because the gun is off face or something else is haywire...