Re: 6.5x.3006
I'm interested in this topic. I've got the .25-'06 and .280 in factory heavy barrel versions, and they bracket the 6.5-'06 with regard to bore diameter. My experience with both is limited.
I found the .25-'06 to be somewhat finicky and the bullet choices limited. The work was done ten years ago and I only just recently acquired the rifle as one of my own. I think that modern powder choices make it a moderately better candidate, and need to review current bullet options.
My experience with the .280 is limited to shooting 20 rounds comprising 4 loads in preliminary ballparking ladder testing, just thsi past Wdnesday, as it happens. I found something that might be promising, but also found some traits that might indicate issues with the rifle itself.
For now, I'm using the Nosler 120gr Ballisic Tip until I get a handle on debugging the rifle. The bullet was chosen as a lower recoil, shorter distance expedient; but has potential for both hunting and precision shooting applications. I will go to the 140BT if I ever feel the need to reach out further. More than that is probably not needed for 100yd, and appeals in the same manner as the 155 Palma does in the .308.
As 6.5's go, I like the .260. It seems the best application of the .308 cases' basic capacity. I feel the same about the .280 and the '06 case. I see the 6.5-'06 as being marginally overbore in the same way as I see the 243.
I think the whole thing boils down to load density percentage.
As chamberings become overbore, it becomes difficult to find loadings that can attain 100% load density percentages without using powders that are really a bit slower than might be ideal. I just don't believe in putting powder into a case unless I know it's all going to actually burn and put all it's energy into driving the bullet; using powder as a filler just doesn't get it for me. You really need to go with heavy bullets and long barrels to get the best efficiency whe you work with such chamberings, and the net effect is not kind to throats.
As I recall, Capt. Bill Huskey is quite familiar and positive with regard to the 6.5-'06, and hopefully, he will join this discussion.
Greg