Thread: Testing a conventional approach to load development

Originally Posted by gimp

Is there any evidence of anyone ever experiencing a dangerous pressure issue when loading the correct powder within book loads?


It probably is wise to be conservative if you're shooting a vintage rifle or a cartridge that isn't a modern bottlenecked case.

Greetings @gimp,
I do remember one reported on the forum a few years back where a max load had blown up a rifle. From memory there were two contributing factors. First the data was for a much softer projectile and second the action, although considered strong, was 100 years old.
To me older data, especially where there the actual projectile is not listed, is always suspect. In other cases the speed of the powder has been changed for whatever reason. I believe that the max load in your work is one of these. The Hodgdon/ADI data lists a max load of 44.5 grains of AR2209 in the .260 with the 142 grain Sierra HPTBT for 2,735fps. It also lists 42.9 grains max of AR2209 with the similar 143 grain Hornady ELDX for 2,759 fps at slightly higher pressure. To me something is screwy here. The 44.5 grain load dates from 2,000 or earlier and AR2209 was sped up around 2,002 and the Hornady ELDX post dates that.
I discovered the speed change in 2019 when working with the 6.6x55. Fortunately I had enough of the old lots of AR2209 and my old chronograph records so I could document the speed change. Your 44.5 grain load should have produced a little over 2,600 fps in your shorter barrel but I suspect you may have got about 2,700 fps. There have been suggestions that AR2209 has been slowed slightly since I purchase the lot I tested in 2019 but still leaving it faster then the 2,000 stuff.
I have posted about this load and change previously so my apologies for any repetition.
In answer to your question above. Is it dangerous? Probably not but the pressure will likely be higher than the 60,000psi book max.
Regards Grandpamac.