Laurie
Laurie,
I've got a Remington 700 6mm Dasher that craters CCI450s at 32.1 of RE-15, which is far from a hot load. Did you ever find the reason for cratering at such a low load? I'd like to make this one work, but might re-chamber to 6 SLR eventually.
Thanks,
Terry
As I understand the issue, it is usually partly down to firing pin tip diameter - the larger it is, the more likely there will be a problem - and the pin to bolt-face hole fit. There are other issues too such as mainspring strength and the mass of the moving bits of the firing mechanism. My FN has a very fat pin tip even by factory rifle standards.
We have a number of 6.5X47L Accuracy International tactical rifle shooters in the UK. They nearly all had to go down the bolt-bushing / tip diameter reduction route to be able to run full pressure loads. When I ran a stock Rem 700 6BR with a 28-inch Border barrel some years back I ended up having to limit my 105gn Berger VLD / VarGet loads to a little under 2,800 fps MV - going up to the next node was impossible due to blanking. It shot fine and won me a few small group patches etc, so it's not the end of the world.
The FN though with 6.5X47 Lapua was a different matter entirely as it just couldn't make use of the cartridge's potential. A Stolle Atlas based rifle had no problem subsequently with its finer tolerances and smaller diameter pin.
It's an issue that would-be 6.5X47L users should be aware of though. The cartridge is rated at a higher peak pressure than its 6.5mm competitors - Creedmoor, 260 Rem and 6.5X55mm SKAN. Creedmoor / 260 factory loads generate around 58,000 psi and that's a sensible level for precision handloads too IMO and they'll deliver the same performance as the 6.5X47L running at getting on for its 63,000 psi maximum having larger capacity cases and able to burn more powder (= more energy input). The 6.5 SKAN does it at even lower pressures - 53,000-55,000 psi - but needs a long action or a no-magazine single-loading set up that usually sees the bolt having to be withdrawn to unload a live round.
These are all pros and cons for a group of similarly performing designs - but people planning a rebarrel or a new build need to be aware of the issues and not fall into the trap that I did with the FN SPR.
As a matter of interest, if you look up the Lapua website for its factory ammunition, its four loadings are all very mild indeed. Assuming that Lapua will almost certainly use sister company Vihtavuori's propellants, a run through QuickLOAD suggests that they'll only generate 50,000-52,000 psi. Lapua developed the cartridge as a short-range number for 300-metre ISSF competition and it has since been adapted successfully to far more demanding tasks. It does them very well, but would-be users need to be aware that it is a small capacity, VERY highly stressed design and that does demand a higher firearm specification.