It took much longer than I expected, but my 375 RUM Improved is done. The official name is the 375 Box Monkey Express (my company is named Box Monkey Distribution Inc.) I just started fire forming brass today and I hope to start working up loads soon. The forming loads used 375 RUM brass and 94.5gr of H4831 under a 300gr Sierra GameKing. I'm getting a very consistent 2625fps with this load with a SD of only 12fps! I had to neck the brass up to 40 caliber and then neck them down to create a false shoulder. The next batch of brass will be 404 Jefferey cases fire formed with the COW method.

The specs are:
- RBLP action T&T'd by SSS
- HS Precision stock (I don't know how long I'll leave it in this stock)
- Sightron SIII 8-32x56 LRMOA scope
- CSR 4 port Muscle Brake
- 30" Brux 1-10" .375 barrel (barrel work done by Sin Arms)

Here's the rifle


On the left is a standard 375 RUM, on the right a fire formed 375 BME with a 350gr Sierra MK seated to touch the lands.


The line up 6BR, 308 Win, 300 WSM, 338/375 Ruger, 375 BME


375 BME next to a 308


This is the average 100 yard 5 shot group while fire forming


The next loads to try will be the 350gr MK and the 235 TSX.

Andrew