Hello,There are several adjustments you will need to make for correct readings.
Assure the bayonet is parallel to bullet track.
Get the correct distance from the centerline of the bore to the top of the bayonet.
Adjust the sensitivity.
Get the correct position of the bayonet from the muzzle (fore and aft)
Size of bullet (bullet mass) may change the positions and settings between different calibers. On my 5.56mm it is more sensitive to getting everything correct than it is with my 6.5mm. Once you have the setup working on a particular rifle what bullet you use will make little difference if any.
This has been my experience with the sporter. I'm making it seems more complex than it really is. I'm sure it will work for you with a little tinkering.
I hope that I am able to set the Sporter to my rifle, but I've good impression reding your comments and suggestions.
I'm waithing for one second hand sporter but if this not enter on my shack I buy one new soon as possible.
Thanks