[Afy]

But does anyone know what powder Lapua uses in their 6mm BR 105 grain ammunition?
They claim a velocity of 2790 fps for it.

So I am thinking take apart the ammo, wiegh the charge, run the numbers in Quick Load, and load up with whatever powder comes the closest.

And then check the accuracy on the target versus factory ammo.

I managed to get four shots into .435 inches at 100 meters, before blowing the fifth shot to a total of .640 inches edge to edge. Twice... I know it was me, because I was nervous.

[ArchAngelCD]

I don't know exactly which powder they are using but I'm almost sure it's a Vihtavuori powder since they are both owned by the same company (http://www.vihtavuori-lapua.com/vihtavuori.php).

[Afy]

Well the powder is 30.3 grains of something. The COAL is 2.322 which is lower than the 3.362 in the manual.

I ran the numbers with N140, N150, N540 and N550 and some others just to check.

Per quickload the N140 has a velocity of 2793 out of a 26 inch barrel.

Now the Max load in the VV manual for the 105 Scenar is 28.9 grs for N140 though QL shows 30.3 being close to max.

The Max in the manual for N540 is 30.4 but QL is showing high pressure at 30.3, additionally the predicted velocity is 2828 fps.

N550 velocity is 2689, and N150 velocity is 2752.

Visually cant tell if it is 150, 540 or 140 since they look about the same.

N-135 and N-133 are showing way too much predicted pressure and velocity.
Also ran numbers for N160, N165, 560 and they dont come close to the velocity at the given charge wieght.

So my plan is to load 5 cartridges each with N140, N540, and N150 and go test at the range and see what happens.

Do you think it is a reasonable assumption and approach. All hinges on the following:

Lapua is using one of their commercially sold powders, and not some other manufacturers powder.

[Offfhand]

Very likely Lapua is not using one of their commercial powders, but one that is not available over the shelf to handloaders. This is quite common with loaded "factory" ammo by most ammo makers. There are a number of reasons for this, requring a longer explaination, but its mostly economical.

[Afy]

Ah well... will know tomorrow. Have loaded the N-150 and N140 which seem most likely based on velocity..
I dont have 540 currently so that will have to wait until Saturday.

[243winxb]

Lapua FAQ -Which powder is used in cartridge?

Our strategy is not to inform individual factory loaded cartridge powder types or powder volumes. Matching powders and volumes are presented in our reloading guide, in principle thus also including our factory loads. My guess would be N540 @ 30.4gr. Velocity is 2776 fps with the Lapua 105 gr Scenar. Lapua is showing a 25 1/2" barrel, so add about 25 or 35 fps to there 2776fps= 2811fps Maximum loading, start low, work up.

[Afy]

I have measured 6 cartridges from six different boxes, 30.3 grains of the powder. So have taken the weight approach. Lets see, will know after the range trip tomorrow afternoon, weather permitting. My guess would be N540 as well, especially since I do not have that powder today.