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Old May 21, 2012, 10:10 AM   #1
thump_rrr
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Join Date: October 12, 2010
Posts: 268
Question about the temperature sensitivity of Varget

I have a Savage 10BA which I bought last fall.
Up to now I've been shooting my handloads using range pickup brass with great success.

All my brass was once fired and separated by headstamp.
The brass was full length sized and had the primer pockets uniformed, flash holes deburred, trimmed to length, chamfered then weighed in .0.5gr lots by weight.

I then fire formed the brass in my rifle and started load development.

In both Winchester and Federal cases using 180gr SMK's I was able to achieve 0.5 moa accuracy using 40.9gr of Varget which I chronographed at 2550fps give or take.
This was in 40F weather.

Last week I bought a box of Lapua brass and did a ladder test along with 30 rounds of 40.9gr and 41.2gr which worked well for me in Win and FC brass.
The ambient temperature was 80F and at the max load in the Sierra manual which is 41.7gr I was only able to achieve 2390fps.
The ladder test seemed inconclusive. The first 4 rounds began stringing vertically then for some reason the next 3 rounds not only leveled off but had nearly identical velocity out of the chronograph which I can't explain why.

Is this due to the ambient temperature or more to do with case volume?
The weight of the Lapua brass is nearly identical to the FC brass and heavier than the Winchester brass by nearly 30gr.
Should I keep pushing the load till I see pressure signs and do another ladder test?

Last edited by thump_rrr; May 21, 2012 at 06:15 PM.
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