My newest long range target / match rig is a custom built 338 Lapua Improved built by Triggered Precision in Idaho and holy cow did I find the load it likes. After scouring the internet for 338 Improved data, I did some load development with the 300 Grain A-Tips. What was interesting with these is they grouped better at 200 yards than 100 yards but they were flying at 2960 FPS with 99 grains of Retumbo in fireformed brass into .5 MOA or less at 200 yards, 100 yard groups were around .75 MOA.
Fast forward to last week, I had some 256 Flatlines with the Tubb nose ring and called up Warner to get some starting load data. The dudes were extremely helpful and gave me a lot of good information. Long story short, one quick round of load dev. and I found my load. 102 Grains of H-1000 pushes the 256 Flatline at 3160 FPS with low single-digit SD's, and I've yet to have a group over 1/4". Anyone with an improved 338 should definitely take a look at this bullet / combo. the rest of the recipe includes fireformed and annealed Lapua brass, FGMM mag primers, custom Hornady dies, .002" neck tension, with the slug seated to have the bearing surface / boat tail junction right at the neck / shoulder junction (around .08" jump in my chamber). The rifle has a 31" 9 twist Brux with a Thunderbeast Ultra 338 on the end.
So far I have about 260 rounds through the improved and I'm really liking the cartridge, the gains over a standard Lapua seem to make it worth the effort of fireforming.
Fast forward to last week, I had some 256 Flatlines with the Tubb nose ring and called up Warner to get some starting load data. The dudes were extremely helpful and gave me a lot of good information. Long story short, one quick round of load dev. and I found my load. 102 Grains of H-1000 pushes the 256 Flatline at 3160 FPS with low single-digit SD's, and I've yet to have a group over 1/4". Anyone with an improved 338 should definitely take a look at this bullet / combo. the rest of the recipe includes fireformed and annealed Lapua brass, FGMM mag primers, custom Hornady dies, .002" neck tension, with the slug seated to have the bearing surface / boat tail junction right at the neck / shoulder junction (around .08" jump in my chamber). The rifle has a 31" 9 twist Brux with a Thunderbeast Ultra 338 on the end.
So far I have about 260 rounds through the improved and I'm really liking the cartridge, the gains over a standard Lapua seem to make it worth the effort of fireforming.
![0UfXvful.jpg](https://i.imgur.com/0UfXvful.jpg)
![555kafzl.jpg](https://i.imgur.com/555kafzl.jpg)