Received some Lapua brass in for my 6.5CM and did some comparison test.
Starline Brass 6.5CM SRP
Wt gr Length " H20 OD ID Wall
1 162.24 1.910 51.44 0.2885 0.261 0.01375
2 163.72 1.912 51.22 0.2880 0.260 0.0140
3 161.82 1.909 51.32 0.2885 0.261 0.01375
4 163.56 1.911 51.14 0.2880 0.260 0.0140
5 163.20 1.912 51.14 0.2885 0.261 0.01375
Avg 162.91 1.9108 51.25 0.01385"
Dev 1.16% 0.583%
Lapua Brass 6.5CM SRP
Wt gr Length " H20 OD ID Wall
1 166.24 1.9125 51.22 0.290 0.261 0.0145
2 165.50 1.9125 51.32 0.290 0.261 0.0145
3 165.46 1.9125 51.38 0.290 0.261 0.0145
4 165.52 1.9125 51.20 0.290 0.261 0.0145
5 165.38 1.9125 51.18 0.290 0.261 0.0145
Avg 165.62 1.9125" 51.26 avg 0.0145"
Dev 0.52% 0.39%
* I weighted all 100 pcs of Lapua brass. Had only 3 that were 166.00 or greater and 2 less than 166.0 > 165.90 with the mean avg between 166.2-166.6gr. If you look closely the heavy one did not have a great loss in volume since several lighter brass were lower.
This is why we spend the $$$ for good brass, consistency from piece to piece. The numbers show it’s almost 1/2 of Starline’s when using avg, Greater if you use the extremes.
With the internal volume being equal I may not have to rework my loads. The only question is the smaller flash hole 0.058” vs 0.062”, how much will it play into this.
This lot of Lapua brass came sized with 0.003” bullet tension, does not require sizing. The earlier lots I had were 0.004” and did require expanding then sizing. All of Starline brass had to be sized.
Note: The above target was shot using sorted brass by weight with less than 0.6gr spread.