Good morning Norwegianwood,
Thank you for your advice.
My hunting trip to Spain for Ibex, Mouflon and Chamois is a hunt of a life time. I don't want to sell myself short on bullet weight. I like a heaver bullet. Will the 120gr perform at a 300 or 400 yard shot ? I know its all about shot placement, but with a lighter bullet I don't want it to run off and we need track it for a day or two. Please give me your idea.
Robert
As said earlier, I don't recommend to shoot further than 350 yards with the Barnes TTSX in a 6.5x55 to be sure of proper bullet expansion.
The impact speed at 350 yards should be close to 2000 fps and enough for proper expansion.
Inside 350 yards it will do the job very well on your intended animals and it will not lose weight after the impact.
Here you see the result of a 120 gr TTSX from my 6.5-06 hitting a deer with the impact speed of around 3150 fps and penetrating 8 inches of neck/spine, continue to cut some ribs and stop after a total of about 24 inches of penetration through hide, bones and muscles.
I also like a heavy bullet sometimes, but I would not use it for very long shots in a 6.5x55.
Specially not if you have problems to stabilize the high bc bullets well and don't get outstanding accuracy.
One of my favorite bullets in 6.5x55 besides the 120 gr TTSX is the 155 gr Lapua Mega.
It has the bc of 0.377 and is a high quality cup and core bullet that performs very well on animals.
It is not the flattest shooting bullet, but personally I use it out to around 270 yards(250 meters) with great results.
When it comes to the 120 gr Nosler Ballistic Tip, I prefer to use it on Roe deer and Chamois sized animals and smaller.
I don't feel confident enough on how well the bullet will perform on shoulder hits on bigger animals.
Personally I prefer Vihtavuori N160 and N560 when reloading for the 6.5x55.
Sometimes I also use N165.
Most of the times I use N160.