Ken, I am in the process of putting together a 260 Rem with the purpose of informal target shooting and varmit obliteration. I am using a 26" medium to heavy coutour barrel that is fluted, no muzzel break. 1 in 9 twist with the intent of shooting 140 gr bullets. My question is if I shoot certain bullets that have a cannelure do these bullets behave differently if they are seated above or below the cannelure. I intend to have the overall length of the loaded round be determined by the ogive just touching the rifleing. this may mean moving the bullet in or out in the case. I have read the optimum seating depth is one bullet diameter. Is there any data to back this up?
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<br>Bullwnkl.

Ignore the cannelure with impunity. Bullets have cannelures for at least two reasons, neither of which applies to all loads:
<br>-- for crimping the mouth of a specific cartridge (the .350 Remington is one example), not for other cartridges of the same caliber (.35 Remington, Winchester, and Whelen, .358 Winchester and Norma Magnum, for example)
<br>-- to control the expansion of the bullet and the jacket splits that permit the expansion
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<br>One-caliber seating is A minimum -- not THE minimum, not optimum.
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<br>Other things determine optimum seating depth
<br>-- free bullet travel
<br>-- magazine length
<br>-- neck length
<br>-- base of bullet a tad (0.050 inch or so) forward of the base of the nect