Do you have a chronograph? You may find that, if your bore is oversize as many of them are, that the RWS rounds you refer to, which have undersize bullets, may not perform as well as you expect, either in accuracy or velocity. RWS brass is great, however.

The Hornady 160g should do better than RWS bullets, because they're larger in diameter - a true .264". They are a tapered nose bullet. If you are happy with their velocity and accuracy, look no further. However, for roe deer you may find that something smaller will do the job better, but try the 160g and see. Smaller bullets should in theory pose problems in terms of having to jump to the lands, but in fact I found their accuracy quite acceptable.

If your velocity and accuracy are still down, a fix is likely to be that Hornady also sell a Carcano bullet which is several thousandth oversize. You need to work with some caution if you use this. Firstly you need to slug the rifle bore to establish exactly what size it is and if it is, in fact, safe at all to use the Carcano bullet. Secondly, if it is, then you must ignore what you have read about COL because this bullet is not tapered like the standard Hornady .264" bullet. So it will jam in the lands,raise pressure alarmingly and also leave the bullet still jammed there if you open the bolt without firing it. So you must seat it much deeper. How deep? You will need a Hornady (a.k.a. Stoney Point) Overall Length Tool to establish this. However the bigger bullet, when used in suitable oversized bores, ensures a much better seal. This means much better velocity and good accuracy. I think that this Carcano bullet should do well at 6,5x54 M.Sch. velocities, (around 2,200 fps), on such game as roe deer.

If you do not have access to an Overall Length Tool and/or do not slug the bore, suggest you stay well away from the Carcano bullet. Don't try to wing it.

If you use the undersize RWS bullets, I have found it helpful to have a second FL sizing die with a sizing button that has been turned down a few thousandths. This allows me to seat the undersize bullet in the neck without it falling out afterwards - and to crimp it too.

I have never had any problems feeding these various rounds in my M1903.