here's a simple formula that can figure out about the velocity attainable with other bullet weights in the same round: Add the two bullet weights together, divide by two, then divide that by the new bullet weight. Multiply the result times the velocity of the known load.
This instance it would go:
1) 129+120=249
2) 249/2=124.5
3) 124.5/120=1.0375
4) 1.0375x3400=3527.5
And 3527.5 is 3500-3550 fps.
As for your other question, you could call Nosler and ask for their writer contact, since they have somebody who takes care of writer requests full-time. Then explain to him that you want to borrow a 26 Nosler rifle with some ammo for test-shooting, in order to write an article. To do that, however, you usually need to have a magazine already committed to running the article.
You can also buy the rifle and some ammo and do the testing, then try to interest a magazine in your review.
I've done it both ways, but the second method is more common among people trying to break into the business.
