357 magnum 180 xtp seated in rear crimp groove.

[30hrrtt]

I have a Ruger bisley acusport in 357 magnum that has a long enough cylinder to load the Hornady 180 xtp crimping in the rear groove.  I just need to make sure my cases are trimmed to the normal minimum trim length.  This increases the case capacity quite a bit.  What kind of gains at safe pressure can I achieve?

The #12 Speer manual lists magnum loads with 180 grain bullets with an overall length of 1.69" using 16.1 grains of H110.

Anybody have any load data or experience with this?

[LaOtto222]

I have not loaded the 180's into the rear groove. I do know that if there is more case capacity, using data from the loading manuals for the normal length bullets should work. You have to be careful what powders you are using. WW296 does not do well (too much pressure can be developed) when there is too much room in the cartridge (a reduced charge). It should be at full capacity or near it anyway. This does not give you a check to just add more powder because of more capacity. Start cautiously with known loading data and work your way up very little at a time. I would be very cautious. Did I mention to be cautious? You have to be careful about pressures. Hand guns are not made as stoutly as a rifle so use hand gun data not rifle data to start with. The rear groove was put in there for rifles in mind and even Hornady #6 does not show data for the rear groove in the rifle section or the hand gun section. I would try 2400 or 4227 to start with, they are a little more forgiving in cases that are not full. Remember work up slowly and watch closely for ANY pressure signs. Proceed at your own risk