I am building a rem 700 mountain rifle and have chosen for several reason the 6.5-06 caliber. I cant understand why this round shoots 100 fps slower than the 25-06 and the 270 win with roughly the same bullet weight. Does anyone understand the math behind this or is this just realoding manual foder.

Looking at my book the 6.5-06 will drive the same weight bullet faster than a 25-06 Just like a 270 will drive the same weight bullet faster than an 6.5. Easier to optain velocity with a larger dia bullet of the same weight. I tend to compare bullets of close to the same Sectional Density not weight. Not sure of your data sometimes they will use the max pressure for the parent. For the 6.5-06 that would be 60,000 for the 270 that is 65,000.

That may explain the large differences in data from different bullet manufactors. It just seems that the printed data I have found seems to be mundane in comparison to its siblings. It reminds me of the 280 remington. here is an execlent round that has been demined by the folks that print this data. Most of the info available showed 140 grain bullets at 2800 to 3000 fps, but yet hornady rates there light mag 140 grain at 3150. So I quess my question should have been is , Just how far can I go with this round!

I trashed primer pockets in the 6.5-06AI at 3200fps.

Don't get hung up on velocity.. 6.5 bullets are pretty darn aerodynmic... even when leaving the Muzzle at less velocity than a 25/06 or a 270, they will end up maintaining more velocity as they range out there....

I shoot 260 Remington, and that 308 sized case will run with a 25/06 pretty darn close up to the 120 grain bullets that are available..

If you are loading 140 grain bullets, then 3000 fps should be just fine.. the difference between that and 3100 fps, can be compensated for with 2 clicks on your scopes elevation knobs, to compensate for the difference in a trajectory table...

Most data in a 6.5/06 is conservative, as it is still considered a wild cat, and doesn't have SAAMI specs to it...

Look at a bullet's sectional density for load comparisons...

the 140s have a SD the same as a 160 grain 7mm bullet or a 190 grain 30 caliber bullet....

So you can compare bullets of the same sectional density or similar cases in different calibers.. such as 270, 280 or 30/06....
look at the same powders fueling those, and start on their lower recommendations and work up...

when I was looking to do the same thing as you are currently doing, I ended up building a 6.5 x 57 instead, because I got the same results as a 6.5/06, with a shorter case, and less powder...

I had the opportunity to use a 6.5/06 and a 6.5/06 AI for comparison results....I went with the shorter case, because I could always bore it out to the 6.5/06 case, if the shorter case didn't give me what I wanted....

I never had to do so..

you made a decent choice.. the 6.5 bullets will fly flat due to their aerodynamics and will penetrate pretty darn deeply due to their high sectional density...you won't be disappointed...

quote:

3000 fps, but yet hornady rates there light mag 140 grain at 3150

I would guess 3000+. I'm sure powders that Hornady uses for their Lit Mags aren't available to us pilgrims.

You will give up very little to factroy 264s

I think one of the problems [?] might be that the 25-06 and 270s are generally a 1-10 twist. Most guys want the 6.5 in the 1-9 or quicker twist. Takes more horsepower to overcome the quicker twist. That is why I most always use a 1-10 in my 6.5s. I`ll worry about the accuracy at 175-200 rather than 100 yds.
Aloha, Mark