The twist rate of this rifle will be capable of handling bullets from 155 to 215 gr, which means the sky is almost the limit in terms of bullet choices. The length of the freebore (throat) may limit you to a certain length (weight) of bullet. Bottom line is that without chamber/throat measurements, there is no way to know with absolute certainty what bullet might load and seat optimally. Nonetheless, there's a pretty good chance as a production rifle that it will have a very generous throat length. Given the barrel length, I'd probably choose a good mid-weight bullet to start...something forgiving and easy to tune, maybe with a tangent ogive, and a decent BC. For example, something like Berger's 175 OTM Match bullet would be a very good choice. They are extremely forgiving and easy to tune, have a pretty decent BC for the weight, and are highly unlikely to exceed the throat length of the rifle, even in the absence of any direct measurements at this point.