Trail Boss....Compressed?

[TwoPoundPull]

Hodgdon/Winchester/IMR load data lists 6.0 - 7.3gn TB for 240gn SWC in .44 mag, looks like anything much over 6.4 is above where the bullet base will be when seated in a Win case.......Looking for 6.7.......The little Cheerios will settle just enough if I tap the case a few times, but as I understand it, TB can do some funny things if compressed.......
Using Missouri and Laser Cast, roll crimp at cannular.....

[Peter M. Eick]

Not a good idea to compress TB. The problem is if you break the donuts you change the burn rate and bad things happen. It tends to burn very quickly based upon what folks have learned.

I make it a rule that if I am using TB, I must be able to shake the powder when I am done and hear it. If you can't seat the bullet and not hear the powder easily shake, try moving to a different powder.

[MichiganScott]

IMR has a PDF explaining how to load Trail Boss. It specifically tells how figure your max load without compression.

http://www.imrpowder.com/PDF/Trail-Boss-data.pdf

[Vulcan Bob]

Peter M. Eick has it right, Trail Boss dose not play nice when compressed! I found out the hard way that Trail Boss will "bridge" in my RCBS Uni-Flow powder measure. I loaded some .38 Special loads with the "new to me" Trail Boss and was distracted by a phone call after charging the cases and when I came back to the bench stupidly forgot to check the powder levels in the block and went ahead and seated the bullets. Well off to the range and commenced to shoot. All was well until one shot felt like a full house .357 mag load in my M-10! All cases ejected ok and found a flattend primer on the big boom case. Needless to say all shooting with that gun and the Trail Boss loads came to a halt. Pulled the bullets and checked the powder charge in each one and found one with about half of the powder it should have had, I assume I found the other half along with the proper charge in the big boomer round. That would have been a compressed load and a check with IMR did have a caution about compressed loads and the possible results of crushed and broken Trail Boss powder flakes. Did a test with the Uni-Flow and found that indeed now and again it would "bridge" in the measure. Well this was a learning experience all around includeing loading bench practice and was was lucky that my Model ten was undamaged and so was my hand. So be carefull with Trail Boss and do not compress it.

[ArchAngelCD]

Like said above, I highly suggest you not compress Trail Boss at all! Pressures can and will spike if you break the donuts, not a good idea...