Since I have an elk hunt scheduled with BearPaw in a few weeks, I thought this would be the perfect time to test a new bullet. I've been playing with the Hammer Bullets 305gr Hunter in my 338/408 Improved and it's working great. This time I'm trying the 260 gr Hammer Hunter in the 338/375 Ruger Striker and I've got high hopes for them so far.Here's the 260gr Hammer bullet next to a 300gr Berger OTM. Think of the Hammer bullets as what the Barnes wishes it could be.
I got out yesterday and just ran pressure tests while checking velocity and I'm pretty impressed so far. Here's my basic process when playing with a new bullet in a cartridge with no published load data:
- Seat bullets .015" off the lands (or at max mag length)
- Determine starting charge weight based on cases with similar capacities. For the 338/375 I start with either 330 Dakota data or just use max 338 Win Mag charges as starting loads.
- Work up the powder charge incrementally by roughly 1% of case capacity.
- Load and fire 1 round at each charge weight over a chorongraph while watching for velocity increases to level off or pressure signs to show.
- Once a max charge has been determined, back that down 1.5% and start shooting groups while adjusting OAL length
- Once OAL has been determined, fine tune powder charge until satisfactory groups are achieved.
Unlike a lot of other bullets though, I haven't really found a need to adjust seating depth with the Hammers. This is 10 shots at 200 yards, with 10 different charge weights with a difference of 340 fps from high to low. This particular gun is pretty sensitive to having the Magneto strapped onto the barrel too, so that accounts for some of the horizontal spread.
The highest velocity was 2725 fps from the 18" barrel with no pressure signs and only .002" case head expansion. I'll load up a few more rounds at the highest charge weight I tested yesterday and try again tomorrow. I don't really see any reason to mess around with pushing the velocity any more. Since this is a hunting gun, all I want is .5 MOA with a hunting bullet and I'm ready to roll. This could be the fastest load development I've done in a long time; done in 15 shots or less!
I was also hoping to recover a bullet from my back stop which is a couple chunks of cedar. The bullets went right through 23" wood and kept on going. My 375 with 260 Accubonds didn't make it through the same chunks of wood!
