7 mm 08

Mark2

New member
I keep hearing from people how the 7 mm 08 is so much faster and flatter shooting than the 308. But when I check ballistics on each round in say 150 grain bullet to keep it equal, the 308 seems to be faster and harder hitting and flatter. Am I wrong.
 
Given same same bullet weight the bigger bore will always have a higher velocity given the SAME pressure levels. The BC of the bullet is what comes into play at longer ranges say 300+ for the higher BC/smaller bullet to catch up.

A classic example on the varmint field is that if a 223 will shoot a 50 grain bullet at XXX velocity the 6X45 will invariabley shoot a 55 grain bullet at the same velocity. Moving up in weight makes a huge diffence as energy is the square of the weight vs a stright velocity increase is a stright gain in energy. Expansion ratios come into pay on what pressures we can rach and in many cases in a gas gun what we can use.It takes gas to move the BCG's and if teh expansion ratio is too high we must adjust the gas port size or location or both. Bolt guns don't have that headache..LOL

Greg
 
Ya. My 24" barreled 7-08 would shoot with less come up than my 30" barreled 308. Both zeroed at 300yds. Both shooting 168 bullets. That's another reason I got rid of the 308.
 
Originally Posted By: Mark2 I keep hearing from people how the 7 mm 08 is so much faster and flatter shooting than the 308. But when I check ballistics on each round in say 150 grain bullet to keep it equal, the 308 seems to be faster and harder hitting and flatter. Am I wrong.

You are dead wrong.
 
All things being equal such as, charge weight, bullet weight, primer, twist. The bigger diameter bore will usually have more velocity. A 6x45 will shot a 55 grain bullet faster then a .223 can shoot a 55 grain bullet. The added volume inside the barrel will allow for more powder to burn before the bullet leaves the muzzle. Where the 7-08 shines is in have a better selection of lighter weight, higher BC bullets. So it may have a better trajectory and carry more speed down range, but muzzle velocities won't be any higher in the same weight class of bullet.
 
There is a shooting sport where you shoot at metallic targets out to 550 yards in 100 meter increments starting at 200 ,meters. The 308 dominated for years, when the 7/08 came on the scene, it was all to obvious to all of us that the 7/08 had much less bullet drop and wind drift than our 308's had. So, the 7/08's replaced the 308's. Now, the 260 Remington is sought after by many due to it's lack of wind drift and bullet drop. Remington makes few if any 260 in the Varmint variety anymore.

The 7mm 150g Nosler ballistic tip(BC ~.500) at 2850 out of a 24" factory tube really shows out at 400 and 500 meters. I shoot a max load of R#19 with a fed 215 in my Rem factory tube. The Nosler bullets are reasonable in price to where you can afford to shoot a bunch of them.

With the 308's, you really need to go with an ultra high BC bullet vs normal bullets to cut down on your wind drift and bullet drop, if you are shooting long distance.
 
The 7-08 rocks. I am on my 3rd one now and will NEVER let this one go. EVER. Have taken more deer with 7-08s than anything else. It is a superb cartridge IMO. Better ballistics than my 308s........
 
Not doubting you. But when I run a quick ballistics check on the 7 mm08 and 308 win with both being 150 grains. At 800 yards the 308 is still flatter
 
Last edited:
I use my I Snipe APP. If it was easier to post pictures here I would post the screen shot of the results of both calibers. But this site isn't as easy as others to do that. I don't do photobucket
 
.415 on the 308 and .413 for the 7 mm 08 Both are 150 grains. I wanted to compare apples to apples Same grains.
 
Originally Posted By: Mark2.415 on the 308 and .413 for the 7 mm 08 Both are 150 grains. I wanted to compare apples to apples Same grains.

What bullets?

As stated, same weight/bullet, the 7mm will have a higher BC.

150gr. Nosler Accubonds/Ballistic Tips:

7mm = .493
.308 = .435

150gr. Partition:

7mm = .456
.308 = .387

I won't go on, but this is the norm. You need a heavier bullet in the .308 to equal the BCs of lighter 7mm bullets.

One of my favorite 7mm bullets is the 162gr A-max. You need a 208gr A-max to equal it's BC....
 
Hornady .308 150gr SST has a BC of .415

The LIGHTER 139gr 7mm SST has a BC of .486.

The 154gr 7mm SST has a BC of .530.

It's no contest........
 
Might not be same style bullet but the grain weight was same. A 139 gr one would presume would fly a bit fast and flatter than 150 gr one.
 
Back
Top