Originally Posted by walrus108
Thanks for that warning taterhead. My suspicions are confirmed. When I started seeing starting loads that varied by more than 1.5grains, it for sure throws up some red flags. Inconsistant batches, or at least a considerable change in formula over the years, must be the reason. I even have the 'one book/one caliber' book where the 10mm IMR data is partially whited out. From an older copy, I was able to see a max load of 9.7grains under a win JHP 180gr with a velocity of 132? (whited out). They had also listed a load of 14.5grains for the Nosler 135gr at 1670fps! I guess they are no longer standing behind those loadings.
Is it safe to download to 8.0 grains of 800x? I know some powders, like BD, will cause pressure problems also if you start too low. If not, 8.0 will be where I start. Better safe than sorry. I would like to use this 800x, so many 10mm guys rant about how great it can be, but it has me very leery. I'm going to contact IMR and see what they have to say about all this. Maybe I'll use my match witness to build some loads with it, but I'm probablly going to stick with Bluedot for these XTP's I want to load. I like my guns and my fingers!
Anybody want to buy a sealed can of 800-x? 2lbs seems like too much of it for me right now!
8.0 grains is not too downloaded at all. It is less than 10% below the powder manufacturer's max (a common reduction for starting loads). It is also way higher than Hornady's start charge. It will be just fine. In fact I have run plenty of 180 grain bullets as low a 7.0 grains. I have burned up a lot of my onhand supply with plinkers just to get rid of it.
The point about downloaded powders causing detonation or other pressure problems has been pretty thoroughly refuted. Speer's #14 manual discusses laboratory inquiries. The problem with slow-burning powder and downloaded charges is that you get really inconsistent velocities and, potentially, accuracy.