Thread: .25-06 7mm-08

Doing a little research, and am now getting a little confused. The .25-06 with 65 grains case capacity pushing a 120gr bullet at 2990fps and 7mm-08 with 52 grains case capacity pushing a 120gr bullet at 3000fps... Assuming the test barrels were the same length, how could the 7mm achieve higher velocities with far less powder?

Possibly due to larger bore size, more likely powder burn rate.

Over bore cartridges need a big charge of slow burning powder, generally. Cartridges with a larger bore size and smaller case will achieve their peak with a smaller charge of faster powder. 120gr is on the lighter side for a 7mm, so you can stoke it up with something like 2206H to get it bitching.

When growing up in Cnterbury I used to use a 117gn Projectile in my 25/06 driven as hard as I could. It Shot flat and killed things a long way away. Rifle was 26 inch barreled 700 and I would buy another.

My Rem 700 7-08 I shot a 140gn projectile also driven hard but out of a 20 inch barrel. Didn't shoot as flat and everything still fell over. Never shot a deer with either though just Tahr and Chamois and rabbits

Used different powders in both. You would need to compare apples with apples, ie identical rifles / bullets.

One is real good at the long range stuff in the appropriate dress and the other not so good but a handier package generally and you can use a bigger bullet if needed. But 26 inch barreled rifles are a complete pain in the arse in the bush.

Over the years I have learned speed is not everything, I like big bullets going slower rather than little going fast. (this from someone who only currently owns .223's)

Would you rather be hit by a truck going slow or a scooter going real fast.

Originally Posted by mikee

Would you rather be hit by a truck going slow or a scooter going real fast.

That's a very good analogy (sp?) !!

Originally Posted by Savage .223

Doing a little research, and am now getting a little confused. The .25-06 with 65 grains case capacity pushing a 120gr bullet at 2990fps and 7mm-08 with 52 grains case capacity pushing a 120gr bullet at 3000fps... Assuming the test barrels were the same length, how could the 7mm achieve higher velocities with far less powder?

Because a bigger case requires more powder to reach the same pressure.
Its like if you held a poha in your open hand and watched it go off it would burn your hand but if you closed your fist around it it would blow your finger(s) off.

Next up bore size, if you take two chamberings with the same case but different bore sizes eg 243,708,308,338fed all the same case with different bore sizes.
Then with all things being equal for the same weight projectile the biggest bore size will always push it faster for the same pressure. It will also slow down faster due to less efficient BC.

Think of it like a hydraulic ram, your pressure is fixed so a bigger ram will push harder.

passing observation - 120gn is basically the heaviest projectile for the 25-06 while it's typically the lightest you would use for the 7mm08.

I was only brave enough to hold a tom thumb in my fingers.

Savage, what powder were you using to get 65gr in the 25 06 case behind a 120gr bullet, sounds......scary
unless I've read your post wrong

Looks like water capacity; QuickLoad has them entered at 65.8gr and 55.0gr respectively.

Id imagine 45-48gr of powder would be the max you would jam in 708, without lookin at the manual.

Originally Posted by jakewire

Savage, what powder were you using to get 65gr in the 25 06 case behind a 120gr bullet, sounds......scary
unless I've read your post wrong

I didn't use any powder, I was just doing some research for possible next caliber and thought it was a bit weird that more powder would push the same weight bullet slower but now I understand why

and 125gr in 308 doing over 3000fps with less powder again

Odd.

When I read that it said case capacity. Not powder.

7mm08 will be flatter than 25-06 any day that ends in y so long as you know what your doing and don't read that ballistic studies bullshit website.

Not that I have any idea why you would want to shoot 120's out of a 7mm08 though, I spose if you couldn't get 162's, 160s, 140s etc to shoot. Out of my 7mm08 I shoot 41.0g 2208 with 162 amax to 2680 fps. Run the numbers out to your desired max range on a 25-06 with vld's and note the drop vs what the 7mm08 will have and make your choice. Realistically nothing will notice the difference.

Back to my real world cave

Chris

Hands up how many guys kept ice cream containers full of tom thumbs and pohas as long as they could after the ban, I threw mine out in the fire heap only two years ago. Then lit them