You will find good loads with Varget, RL-15.5, N150 in the 32-34 range with 103-110 grain bullet weights, SW Precision tends to need a few tenths of a grain less than Varget and H4350 tends to need around 2 grains more to reach the same velocity. I pretty much stay in the 32-32.5 range with Varget and depending on the barrel this usually puts me between 2810-2860fps with 110 A-tips, 109 ELD's, 109 Hybids and 108 Elite hunters.
A few years ago Precision Rifle Blog published work Mark Gordon of SAC was doing and there have been a few podcast's with Scott Satterlee on the same subject as well, regarding bullet seating depth. Their findings suggested that jumping your bullet .055" or more led to more consistent results for the life of the barrel without the need to tune seating depth every few hundred rounds verses seating closer to the lands. I have adopted this approach with my last 3-4 barrels have shared that same experience for the most part. While I can't say I never needed to change seating depth, I did find that it seemed to hold true for 1-2 thousand rounds. I usually exhausted my supply of a given bullet type before the barrel quit shooting. Before adopting this approach, I'd seat to .015-.025" and notice changes in POI as well as groups opening up as the throat geometry changed leading load tuning.
When I started with the 6gt in 2019, Hornady was the only one making brass for a few months and it shot well. I picked up some Alpha brass two years ago and it shot consistently tighter. Lapua advised they will start production at this years Shot show, but I have not heard a release date on it yet.
Thank You this is a great help.
I am currently loading for 338 Lapua as a precision rifle (Savage elite). I am getting groups of 3 with a longest distance between the holes of about .625 at 100 yards. I am new to this discipline so I hope to do better but how much?
I have also started loading with the same attention to detail for the 308 in an M-24 which I just acquired and as above I am shopping for a 6mmGT.
For the .338 and .308 above, mindful of throat erosion, from boat tail bullets, for some of my practice loads, I am using a flat base bullet to see how it groups compared to the the boat tail. It would be nice to practice with the flat base if I could cut down on barrel ware.
This is the latest from Lapua's web site on the 6 MM GT:
"New for the autumn of 2024, Lapua will offer a superior choice for competitive shooters with Lapua 6mm GT cartridge cases. Experience unparalleled consistency, quality, and durability with Lapua’s 6mm GT as you pursue excellence in the world of practical precision rifle sports.
The incredible growth witnessed in PRS, NRL, and similar competitive shooting disciplines the past 10 years has heralded the development of high performance, short-action cartridges like the 6mm GT. The GT provides flawless feeding from bolt-action, magazine feed platforms when utilizing the latest high ballistic coefficient 6mm projectiles. Its ultra-efficient cartridge provides low recoil impulse for easy target acquisition and offers excellent precision and velocity consistency. The Lapua 6mm GT difference: We provide superior cartridge geometry that is based on the original 6.5×47 Lapua parent case. This maximizes longevity and optimizes case capacity for the competitive shooter."
It is also interesting to note that Brownells lists it in their catalog as "out of stock notify me" so I would take that as progress.
