Swarovski & Ken Farrell bases

[Rob Syl]

What am I missing here? I have a Swarovski 5-18X44 with a ballistic turret and a Ken Farrell 10 degree base on a cooper 280 Ackley . The Swarovski BT is maxed out at 400 yards dead on. I assumed that I should be able adjust to a further range. Anyone with experience with this combination?

 

[bruce_ventura]

I'm not clear about the problem. Are you saying that one full turn of the BT turret only gets you to 400 yds (from a 100 yd zero)? Or are you saying that the turret stops rotating before one full turn?

Depending on the bullet, load and elevation, the 280 AI should drop about 6 moa from a 100 yd zero. The BT turret on a Z5 should rotate about 10.5 MOA. You should be able to get out to at least 500 yds, maybe even 600 yds with a 200 yd zero.

If the reticle stops rotating before one full turn, your rifle probably has a boresight misalignment between the scope tube and rifle bore axes. Alignment errors of this type are actually quite common in factory rifles. In this case, you should switch to a 20 moa base or use Burris Signature rings.

 

[Rob Syl]

I'm not clear about the problem. Are you saying that one full turn of the BT turret only gets you to 400 yds (from a 100 yd zero)? Or are you saying that the turret stops rotating before one full turn?

Depending on the bullet, load and elevation, the 280 AI should drop about 6 moa from a 100 yd zero. The BT turret on a Z5 should rotate about 10.5 MOA. You should be able to get out to at least 500 yds, maybe even 600 yds with a 200 yd zero.

If the reticle stops rotating before one full turn, your rifle probably has a boresight misalignment between the scope tube and rifle bore axes. Alignment errors of this type are actually quite common in factory rifles. In this case, you should switch to a 20 moa base or use Burris Signature rings.

Exactly, the BT is maxed out in the elevation adjustment at 400 yards for no hold over. I forgot to mention that I am using Ken Farrell rings as well. I'm shooting 140 Nosler Accubonds at about 2950fps. Switching to a 20 MOA base is what I'm leaning to but, at this point I'm seeking other opinions and experiences, before I go 20 MOA bases. Just in case I have overlooked something.

If I were to go to 20 MOA bases with the load above what do people think is a reasonable max dead on with the scope and BT combination?
Thanks.

 

[bruce_ventura]

Zero at 250 yds (2" high at 200 yds) and the BT turret should get you out to 650 yds with that load at 5,000 ft elevation, 59 F. YMMV, depending on scope height, measured BC, etc.

 

[bruce_ventura]

I retread your post and am now confused about which scope you have. 5-18X44 is which model?

 

[Rob Syl]

I retread your post and am now confused about which scope you have. 5-18X44 is which model?

It is a Z5 3.5-18X44 BT. Sorry for any confusion there, I got distracted while writing the first post and rushed it out.