Which RS powder for 6x47 Lapua?

[Re-Pete]

RS doesn't have any info/powder recommendations for this calibre, and I wondered if anyone out there is using one of their powders.

Pete

[BlueBoy69]

You should be able to use the same powders as the 6 XC.

Though both operate at roughly the same max pressure, you'd need to use slightly lower charges as the 6×47 has a slightly smaller capacity case.

See attached QuickLOAD computed suitable powders file for other options.

6×47.txt

[Re-Pete]

Thanks BlueBoy, I have QL..............I really must read the manual 🙄................

My best result so far has been with RS 62 and 105 grain Scenars at 3000 fps.

Pete

[BlueBoy69]

No problem.

I've not read it fully myself as it's quite a tome.

Anyway here's data for 105 gr Scenars. I don't known which version you have, the slightly longer GB478 or the slightly shorter GB542, so here's one for each. Both are at max COAL.

The length difference is so small that it doesn't really change the list all that much to be honest.

 

 

6×47 - 105 gr Scenar (GB478) - Max COAL .txt

6×47 - 105 gr Scenar (GB542) - Max COAL .txt

[Re-Pete]

Interesting..........putting my parameters into QL, plus 39.8 grains of RS 60  (col 67.8mm), I'm looking at a Pmax of 60793 psi and MV 3150fps, which I have to say is a tad too hot for me............!!

(I have the GB478 version of 105's)

Pete

[BlueBoy69]

Even using the shorter COAL, I take it you have tweaked some of the other settings somewhere, such as a smaller case capacity (46.65 grains of H2O) to get that pressure? Whatever the case, even at the standard of volume of 47 grains, it's still rather high (59,689 PSI) at your COAL and 39.8 grains of RS60.

Looking at the computed data, RS70 seems a better bet for a mildly (11% NG) double base propellant, that or go with RS62 if you want single base. Reloader 26 gives the best MV vs pressure, but that's also a double base propellant.

Neil

[Re-Pete]

I've found the H2O case capacities to be new: 46.76 grains, once fired: 47.84. I assume that QL adjusts for useable case capacity based on inputted COL, and bullet length.

Having used QL for some years now, there have been a few occasions when the predictions have been way off the actual result obtained, notably when using RS52.

Pete

[BlueBoy69]

Yes QuickLOAD computes the useable case capacity based on the inputted COAL and projectile rear profile.

QuickLOAD has a multitude of parameters, but it is still missing a multitude of factors and is essentially just a model. As you undoubtedly know, the accuracy of its predictions are only as good as the inputted data (user and integral), and ultimately, the model itself. It should always be treated as a guide, and not as fact.

Neil

[Popsbengo]

49 minutes ago, Re-Pete said:

I've found the H2O case capacities to be new: 46.76 grains, once fired: 47.84. I assume that QL adjusts for useable case capacity based on inputted COL, and bullet length.

Having used QL for some years now, there have been a few occasions when the predictions have been way off the actual result obtained, notably when using RS52.

Pete

I find that QL needs tweaking to align actual measured H2O capacity with their calculation from the library of standard dimensions.  My understanding is that the position of the base of the bullet is important to calculate bullet barrel time so I try to measure and ensure that's correct and then tweak other factors to arrive at the correct H2O number.  Seems to give me a reasonable set of data.

I find QL to be a clunky application - possibly due to age and the cost of time to re-write a more slick version

[Charlts]

On the subject of 6x47, is anyone shooting115’s? If so why sort of COAL do you work with?

[Re-Pete]

DTAC's at 68.5mm.

Pete

[Charlts]

3 hours ago, Re-Pete said:

DTAC's at 68.5mm.

Pete

Cheers Pete