Any special concerns working up a load with a dedicated can on it?

[teddy12b]

I've never worked up a load for a rifle that has a dedicated can on it. I'm wondering if there are any special concerns I should be aware of in the process. In the past I'd already worked up a load for this rifle that I was very happy with. For me when I was an SD under 7.0 that was great. Recently after putting the can on it I played with my new Garmin chrono and my numbers had blown up using the same recipe.

The rifle in question is a Ruger precision rifle in 338 Lapua with a YHM Bad Larry. I'm using Lapua brass, H1000, Fed GMM primers, and Fort Scott 250gr bullets.

 

[Old Man with Gun]

Nothing special, make sure your bullets stabilize if you are trying something crazy. But other than that, same as always.

 

[Doom]

One issue to be aware of is choosing a powder that burns completely in the barrel before the can. Otherwise you will be cleaning based on the can and not the rifle. This will likely be the faster powders and unfortunately the ones with the lower velocities.