I have an ultralight BMG upper with a 24" barrel.  I reload API rounds stricktly following published load data with 5010 and H50BMG powder.  My rounds are communig out of the muzzel at ~2,500 fps, remarkalbly less than the ~3,000 expected from a 36" or 45" test barrel.  Has anybody expiremented with loading powders other than the above industry standards that could increase velocity out of a short barrel without making an overly hot load?  Would using a slightly faster burning powder help regain some of the velocity loss of the short barrel?

I can't answer your question but I am just curious what kind of accuracy you are getting?  I ordered an Ultralite 50 with the 24 inch barrel and it should arrive tomorrow.  I have been wanting a 50 for years and finally broke down and got one.  I will start reloading 50 cal. hopefully by summer.

The accuracy is terrific.  I mostly "clover" leaf the target at 100 m.  I ding old, empty propane bottles at 450 m.  Recoil is very mild, but watch that muzzle flip.  However, again, with maximum loads I clock in right at 2500 fps with 647 grain APIs.  

You could try some VV24N41 powder... it's slightly faster than H50BMG...

http://www.hodgdon.com/data/general/burnratechart.php

There's supposed to be a new powder available from Hodgdon: US869, that's getting good results, but I don't know where it places in the burn charts...

Thanks.  I am also looking for you expirenced reloaders to chime in on my assumption that faster powders will increase velocity out of a short barrel.  Does my hypothesis have any grounds in physics?  Also, I would greatly apreciate any load data for 50 BMG loading with powders aprreciably faster than H5010 or H50BMG.

Quoted: You could try some VV24N41 powder... it's slightly faster than H50BMG... http://www.hodgdon.com/data/general/burnratechart.php There's supposed to be a new powder available from Hodgdon: US869, that's getting good results, but I don't know where it places in the burn charts...

Its posted on the Hodgdon website. The data shows US869 uses more powder so it must be slower than H50BMG.