stubble, I won't dispute your results, I was just working from my own experiences. Several years ago, I worked with Nosler and their ballistic tip bullets. Seems that I could push their 140 gr 7mm BT bullet beyond their speed window with a 7mm Rem Mag. They recorded numerious failures from individuals across the crountry and ended up redesigning the BT bullet. Back then, in my testing, I believed the bullets were actually failing in air due to the velosity. I know todays BT is a completely different bullet, but I still worry that a full power load in a 300 RUM, you can push a 180 gr bullet pretty hard. And a 165 gr, churning 3400-3500 fps, i think, is outside of the BT's window of performance. I just think at the speeds generated by the 300RUM, non-rapid expansion bullets are better suited. Just my $.02.

There must be some GOOD reason why Browning dropped the 300RUM from their line. (?)

Economics.Since most people can't take advantage of the extra velocity and don't like the recoil that the 300ultramag delivers,sales have been slow.

I should have bought a 75 in 300 UM when Sako dropped them in favor of selling more short mags, lets face it is a specialized cartridge but a very good cartridge design at that. Some posters at other sites are reporting unbelievable 300 yard groups with Sako 75's probably a combination of gun and cartridge IMHO . Stubblejumper is probably the most experienced with this cartridge on this board and I haven't heard too many negatives from him when it comes to this cartridge.

I had the best accuracy with IMR 7828 useing 180's...

With all due respect to stubble, I have never had luck with his very hot loads. I am sure he has built top notch rifles which probably helps.

The gun is not for everybody. But neither is alot of specialized rounds like the 6.5-284. or the 22-243 middlestead.

Yes, I hear you, however your comparison to the wildcats, 6.5-284 and 22-243, is not valid. The 300RUM was introduced as one more competitor for the top slot, .30cal cartridge. Had anyone been warning, early on, how finicky the 300RUM was going to be, in terms of OAL, primers, propellents and bullets, I doubt that the cartridge would've gotten off the ground at all.
I know of too many hunters who have for years, gotten excellent accuracy from the 300WinMag and the 300WeatherbyMag, without test firing eight or nine hundred rounds, before hitting on a formula that produces accectable groups. So, bottom line being, that if one has to sacrifice 200fps to get a cartridge that likes more loads, what is the big deal. Forget the 300RUM and go with proven performance in a cartridge, for which acceptable groups come easier. I am happy for those who have struggled through finding what works with their particular rifle, and are getting great groups with high velocity loads, out of their 300RUM. Some folks enjoy working through that particular exercise and I respect that. I simply believe that as a production cartridge, the 300RUM will not be with us long. This, not only because of the difficulty of finding acceptable fodder, but because of short barrel life that goes along with high velocity in big case magnums.
Even if we accept rebarreling at 1000-1200 rounds, are we to assume that the cartridge load search must begin all over again?
I received lots of help from bigcountry and others, when I was struggling with my Browning Stalker in 300RUM. I really do appreciate the time that others took to help me. bigcountry offered to go to the range with me and take a look at things and again, that sort of kindness is appreciated. However, I did not have it in me to continue with that cartridge and since I was able to sell with very little loss, the 300RUM went down the road to someone else. I have loaded well over a dozen high powered cartridges in the past and have never been so frustrated as I was with the 300RUM in that Browning. After reading of others' problems with the 300RUM in various models of rifles, I had to discount any problems with the Browning and lay the problem on the cartridge. I have held a dealer's FFL for many years and hear countless stories of difficulties, from hand loaders. Nothing matches the numbers of bad reports that I have heard, regarding the 300RUM's hand loads being hard to find, with acceptable performance.
Add to all of that, the fact that the 300RUM has no draw, in terms of being the biggest, badest, fastest .30cal. Some have said that not everyone can handle a high priced sports car and that they need to drive a Chevy. Well, the 300RUM is at best, an Edsel.