I've run both the 180 and 198 Flatlines using .308 Win. For the 198s, I used a 30" 8.0-twist barrels at ~2650 fps. An 8.0-twist was suggested by the Berger Twist Rate calculator as the minimum twist rate necessary to achieve an Sg of 1.5. Frankly, I think that is an underestimate and a minimum of ~7.5-twist would be better.
PVA's Seneca 198 gr bullet is 0.082" longer than the 198 Flatline, but they recommend a minimum 9.0-twist, which is way too slow for a bullet that long. Anyone wishing to run these and get the most out of them ought to be thinking about at least an 8-twist, and probably more like a 7.5-twist barrel. The velocities attainable with larger capacity cartridges than the .308 Win will certainly help, but increased velocity is usually a poor substitute for a faster twist rate.
Unless we get positibe amd encouraging real time reports, we cant be sure if they work. With your experience, its evident that are NOT smooth sailing, and might have some issues. Could tight bore 308 be helpful in better sealing of gases etc?
What intrigues me is that solids seem to work pretty well for the ELR, Ko2M categories in the 375s, 408s and 416s. Why not the 30cal then?
I have dropped points to vertical (mixed two different loads in a match). No, it does not feel good at all.
Interested in whats different with the PVA 198gr solids with even higher claimed BC than the Warner flatlines.
Yes I noted the two different BCs as well on their webpage.The only thing you could realistically do would be to measure and compare them. The fact that the PVA bullet is 0.082" longer than the FL198 for the same weight suggests it may also be "pointier". I routinely estimate bullets BCs using LabRadar velocity data, and for lead core bullets at least, the numbers are surprisingly good. The estimate I obtained for the FL198 G7 BC was 0.425. PVA lists two different G7 BCs for their Seneca 198 bullet on the same webpage; first they state it is 0.461, and right below that it is listed as 0.421, so I really can't tell which is the correct value. Nonetheless, an extra 0.082" bullet OAL ought to be worth at least some increase in BC, although a faster-than-8-twist barrel would likely also be a necessity.