COAL vs. Ogive (Hornady factory)?

[earthquake]

This might be a dumb question, but in looking over a couple boxes of Hornady's 6.5CM Amax ammo, I see the 140 gr is 2.810" COAL, and the 120 gr is 2.715" COAL.

Since they're obviously different bullets, would the ogive measurement be the same, close, ???

I'm just wondering how much that 0.095" difference makes in the chamber. What is a "standard" chamber to the riflings measured for the 6.5CM? I'm still waiting on the rifle, and am trying to figure out what ammo I should try first. I was just surprised to see the COAL difference was that big. Is that a big difference? Seems like almost 1/10 of and inch would be, especially if most people seat bullets in the thousandths range off the rifling. Thanks in advance!

 

[NoFail]

Re: COAL vs. Ogive (Hornady factory)?

I'm not familiar with 6.5 Creedmore. But 20gr is a substantial jump in weight in these regards. I assume the 140 gr bullet is about that much longer, the .095"? But where do the ogive datums end up from a measurement from the base of each bullet? About the same from the bases of both bullets? I wouldn't think so but if they were then that would explain a lot. But the 140 gr just has to be longer than the 120. But you know that.

Further thought on it, could be the seating depth of the 120 is actually deeper in the case mouth. It is a lighter bullet, perhaps they found it's optimal seating depth to be deeper, and being lighter they are able to get away with it without high pressure signs? who knows... I'm probably way off, just throwing it out there.

 

[dustinoif3]

Re: COAL vs. Ogive (Hornady factory)?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">I'm not familiar with 6.5 Creedmore. But 20gr is a substantial jump in weight in these regards. I assume the 140 gr bullet is about that much longer, the .095"? But where do the ogive datums end up from a measurement from the base of each bullet? About the same from the bases of both bullets? I wouldn't think so but if they were then that would explain a lot. But the 140 gr just has to be longer than the 120. But you know that.

Further thought on it, could be the seating depth of the 120 is actually deeper in the case mouth. It is a lighter bullet, perhaps they found it's optimal seating depth to be deeper, and being lighter they are able to get away with it without high pressure signs? who knows... I'm probably way off, just throwing it out there.
</div></div>

I believe you are all over it