[quote=jwall]flattop - still not arguing either.
If you will compare 6.5 & 270 bullets with similar S Ds (sectional densities) you'll find the B Cs (ballistic coefficients) are awfully close. A few gun writers pointed out the accurate way to compare cals/cart.s yrs. ago.
Then with the heavier 270 bullets you'll have similar trajectories and BETTER wind bucking, & have more fpe, because they're heavier.
I am NOT trying to put down the 6.5s at all. It is not an equal comparison to base the comparison on bullet weight alone. That would amount to 'ballistic gack'.
The 260 & 6.5s are FINE hunting cartridges. They're just not as strong as some.
I find this to be categorically not true.
The SD of the 6.5mm bullets are as follows: 120g-0.246, 130g-0.266, 140g-0.287. The .270 bullets: 130g-0.242, 140g-0.261, 150g-0.279. The BCs of Berger bullets in 6.5mm: 130g-0.552, 140g-0.612. In .270: 130g-0.452, 140g-0.487, 150g-0.531.
So lets pick bullets of similar SDs to compare. Since a hunting bullet from Berger is not available in 6.5mm, lets compare the 130g bullet in 6.5mm to the 140g bullet in .270. SDs are 0.266 vs 0.261 respectively.
On the Nosler website, the 6.5-06 lists a max velocity of 3058 fps with 23" barrel and a 130g bullet. The .270 Winchester max velocity with 140g bullet of 2910 fps with 24" barrel.
So using the BC information of both bullets at those starting velocities here are the ballistics according to JBM with a 100 yard zero and a 10 mph 90 degree cross wind.
300 yards the 130g 6.5mm bullet drops 10"/3.2MOA, drifts 4.8"/1.5MOA with energy of 1894 ft/lbs. The 140g .270 bullets drops 11.8"/3.7MOA, drifts 6"/1.9MOA with 1740 ft/lbs. At 600 yards, the 6.5mm bullet drops 66.9"/10.6MOA and drifts 21.3"/3.4MOA with 1282 ft/lbs, the .270 bullet drops 79"/12.6MOA and drifts 26.8"/4.3MOA with 1098 ft/lbs.
So the 6.5 mm have a higher BCs than the .270 bullets at similar SDs. They will drop/drift less and have higher retained ft/lbs than the .270 bullets started at similar velocities due to the higher BCs.
The data above shows that ballistically the 6.5-06 is a better chambering than the .270 Winchester.
Not sure the differences are enough to matter to anyone, but the data seems to argue directly with your post.[/quote
This a short response for now. (Upper Case for EMPHASIS only)
1. You think .005 diff is much between 130 6.5 & 140 270?
Do you think 0.005 is much difference b/t the SDs of the two bullets? The difference b/t the 140g 6.5mm and the 150g .270 was greater than my example, that is why I choose my example.2. I notice you didn't print any diff in B C between the two.
I printed the differences in BC above in my original post. The 130g 6.5mm bullet has a BC of 0.552, the 140g .270 bullet has a BC of 0.487. The 150g .270 bullet does not have a BC equal to that of the 130g 6.5mm bullet.3. There's always difference in loading manuals PER velocity.
I have been able to beat 2910 fps /140gr in 270 closer to
3000 fps w/appropriate powders & 24" bll.
If that is the case, I am sure the same argument can be made for the 6.5-06 being able to be pushed faster than the 3058 fps listed in my example.4. With SIMILAR s d & bc - the heavier bullet will have SIMILAR
trajectory and have higher energy because of wt.
The formula for energy is 1/2 mass times velocity squared. The heavier bullet has more energy pending the velocity of the projectile. In our case, the 6.5mm bullet is going 2561 fps at 300y and 2108 fps at 600 yards, the .270 bullet 2366 and 1879 fps respectively. Therefore, since the less mass bullet is going faster, the energy is higher for the less mass bullet since velocity is squared. BC is what is important for retained velocity/energy and trajectory. The point is that bullets of similar SDs between the 6.5 and .270 do not have similar BCs. The 6.5mm BCs are higher.5. I know this thread is about 6.5s & hunting; My part focused
on 6.5X55, 6.5 Creed, & 260 Rem. YES the 6.5-06 is MUCH MORE
comparable to 270 in powder capacity and vel. et.al.
Shouldn't we be comparing the two calibers in chamberings with similar case capacity? Also, lets compare the 260 Rem with 130g Bergers at Nosler max velocity of 2838 fps. Here are the results: 260 Rem at 300 yards-12.2"/3.9 drop and 5.4"/1.7MOA drift, 600 yards- 79.9"/12.7 drop and 24"/3.8MOA drift. Retained velocity/energy at 300/600 yards are 2361fps/1609 ft/lbs and 1929fps/1074 ft/lbs. So, the .270 Win is 0.4"/0.2MOA flatter with 0.6"/0.2MOA more wind drift to 300 yards with similar fps (2366 vs 2361) and 131 more ft/lbs. At 600 yards, the .270 Win is 0.9"/0.1MOA flatter with 2.8"/0.5MOA more wind drift with 24 more fps and 50 more ft/lbs. Basically, ballistically the .260 Rem shooting a 130g Berger hunting VLD at 2838 fps is nearly identical to a .270 Win shooting a 140g Berger hunting VLD at 2910 fps.I just returned from hunting (saw nothing). I have to get ready for some company. Will respond more later.
Jerry
