Getting a consistent cheekweld w/new Tikka T3?

[EL34]

Got a new Tikka T3, and am having a problem shooting groups. I think (well, I'm pretty sure), my problem is getting a consistent cheekweld on the stock. What's happening, is during a 5 round string I'm shanking one or two shots, with the rest going into .185"-.329". The rifle only has a 3 round cap. in the magazine, so I'm reloading part way through the string. I'm thinking I need to put something on the stock pack, as a reference point, any good ideas on what to use/how to do that? Additional info, it's a .223 Rem, and I'm using a Triad stock pack, and Harris bipod, happens both from the bench, and prone. TIA
Just an FYI, the new Tikka T3 .223's are no longer 1X8.

 

[Caliper]

What do you mean by "shanking" a shot? Are the last two shots close to each other or random? It does sound like you are disrupting your NPOA during reloading.

When you are reloading the rifle, are you just swapping mags, or dropping rounds in the recever? Either way, practice doing this using your trigger hand only and not moving your elbow on the mat or your head on the stock. Place whatever you need for the reload in a good position on the bench/mat to facilitate this.

A reference point for your cheek would work, but I'm more from the school of thought that your head should be "turkey necked" forward. Stretch your head forward before placing it on the stock. This way your head is fully extended on the stock and in the same place each time. You may have to move your scope further forward to achieve this tough.