Thread: Large MV variation from trueing

Keen to pick the brains of some who may really know the weeds better. I have recently finished a load for my new 260 shooting the 142 Nosler Accubond Long Range projectile. For all my loads and testing throughout, the labradar consistently gave me 2700+ fps which I was happy with as my speed goal for the load.

Today I trued using the Kestrel 5700 with custom drag model etc. As a result MV was trued at 2574fps. I confirmed this true at another intermediate range and it was bang on. My zero was on and all else in the kestrel was correct. Even cross checked to my old ballistic app. Accuracy was mint so happy there.

Where I am getting at is how do you end up with such a large MV variation from a tool like a labradar? I’ve trued a few rifles now and some have been on with the labradar and others have required up to a 40-60 fps adjustment but never have I needed to adjust this much before. It’s accurate and on target so that is good but it does have me wondering how the heck the speed is so far out and if I need to re think my load as that is much slower then I would settle for.

Thoughts from those who know their stuff?