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im dumb and just dont know , 7mm-08 and 308 differences 18.5-20in barrel

G

gumby510

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Minuteman
Dec 22, 2013
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Appleton Wisconsin
Hello, im a beginner in long distance shooting, im currently building my custom tikka t3 and im trying to make an informed decision and make sense of the differences of these 2 calibers.

so I need your help

im trying to decide the differences between only these 2 calibers 308 and 7mm-08. Ive been doing quite a bit of research and havent found the answer ive been looking for.

both barrels would be 18-20in the 308(1:10 twist) 7mm-08 (1:9.5 twist)
my shooting distances will be mostly 300-600yds and some 600-1200(1200yd range 1.5 hours away, 600yd range 45min away, 300yd range 30min away)
95% target shooting 5% hog hunting sub 400yds.

I believe 7mm-08 rounds work in aics 308 magazines from what ive read so they will work with the chassis I own(mdt lss)
for a bit ill be shooting factory loads then eventually getting into hand loading(currently I do not hand load)

308 is widely available with factory match loads, cheap to shoot and barrel life is great, seems to the standard caliber because it does everything well

7mm-08 has less recoil (17%), flatter shooting, less effected by wind, similar "knock down" as 308, once into reloading there appears to be lots of options

I dont really know what the barrel life is for 7mm-08, ive read 308 is in the realm of 6-7k

so lets say both the 308 and 7mm08 are both hand loaded using the brand and weight 155gr and 165gr bullets with all other factors being the same will the 7mm08 still carry the flatter shooting less effected by wind advantage

is 7mm-08 worth it?

set me straight guys

I could use some more pros and cons between the two

sorry if your tired of these types of comparisons
 
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7mm bullet has higher BC than comparable weight 30 caliber bullet so that will help it cut through the wind better. BC (ballistics coefficient) in simple terms is how aerodynamic the bullet is. The longer 7mm bullet is more aerodynamic than the same weight 30 caliber bullet.
 
Go to Midway and look at the ballistic coefficients of the 30cal 168 SMK, 175 SMK, and Berger 168gr Classic Hunter & VLD.

Then look at the ballistic coefficients of the .284/7mm 168 SMK, 175 SMK, and Berger 168gr Classic Hunter & VLD.

Assuming the same barrel length and same weight bullet, the 7-08 will probably be 50-100fps slower than the 308 but the higher ballistic coefficient should make it fly flatter with less drift at extended ranges.

Big issue with a 7-08 right now, IMO, is Hornady's suspension of the 162s which many folks believe are more optimal for the 7-08's case capacity.

My opinion? Skip both the 7-08 and the 308 and spin up a 6.5 Creedmoor.
 
Thank you LCDR JGB that gives me a better perspective on things. I do plan on reloading just not right away.

7mm-08 is making more sense except for the higher factory ammo cost but after I start reloading its negligible.
 
So because Beretta doesnt do a good job supporting tikka I ended up with a LH tikka t3 lite 308.

I was trying to get a heavier barrel through Beretta and thats a no go.

So sometime this year I plan buying a Bartlein Rem. Varmint/Sendero, 1-9 twist, 5r rifling and cut and threaded to either 18.5 or 20in.

As stated before I wont be getting into reloading until late this year. distance will be 100-600yds most of the time with going out to the 1000yd range every once and awile.

My question is at 18.5-20in which will perform better the 7mm08 or 308. Also im really only interested in these calibers with one of the big reasons being barrel life.


this is how she currently sits( waiting on my seekins 34mm 6/4 low mounts to show up)
tikka.jpg
 
[MENTION=95246]gumby510[/MENTION], you do not need a 1/9 barrel with a 18-20" 308. A 1/11.25 or even a 1/12 will suit most of your applications. 1/10 is for 200+gr. 1/9 and 1/8 are for the real monsters (e.g., Berger 230gr) that only a 300 Win Mag or 300 Norma can push.

In terms of barrel life, a 308 will win out. But ask yourself, when is the last time you've toasted a barrel? Get what you want to shoot and go with that.

7mm can take advantage of high BC bullets, but you quickly run into mag length problems with the heavies. Not good for a repeater rifle. Also, there is a limited selection in the 160gr range, which is about the right weight that a 7-08 can push with any kind of authority. Also, most shooters that use the 7mm are trying to buck the wind, and speed helps with that. So, chopping off several inches of barrel will diminish the edge that the 7mm BC will give you against the wind.

With a 18-20" barrel, you would probably be better served shooting 168s-190s with a 308. I would concentrate on the Hornady 178 BTHP or the SMK 175 if you're looking to get past 800 yds.
 
A 7mm08 will beat the pants off a 308 with equal barrel length. The difference in consistency past 750 yards or so will be huge.

Easy choice.

Make sure you get a barrel that's at least a 1:9 for the 7mm. 1:8.5 is good too.

Mark Gordon at SAC does real nice work on the Tikkas.
 
To address other points:

Barrel life of the 7mm08 will be a bit shorter than 308. Expect 3000-5000 rounds, depending.

Recoil will in fact NOT be lighter with the 7mm if you shoot the heavyish bullets (160+)

7mm08 will provide GREATER energy on the target at any distance, but particularly past 600-700 yards. That's assuming the 162@2700 vs 175@2650, both reasonable expectations from ~19" barrels...though admittedly a shade optimistic.

The 7mm will allow you to put a higher sectional density bullet on target with higher energy.

The 140gr Bergers fly fast and nice, and are devastating on game.

7mm08 fits and feeds great in any mag 308 does, though it's helpful to the 7mm08s performance if you load them longer. AICS magazines accommodate 2.850", but can be modified to take even longer cartridges. The 7mm08 can benefit from that.
 
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7mm 08 all the way. And dont look back... 308 is just popular because of its history with the military. 7mm08 out does it by far.
 
I have a 708 with a 20" #4 Krieger barrel with a 9.5 twist. I shoot the Berger 140 VLD and it hammers. I would go with a 9 or faster twist if you wanted to shoot heavier than 140 grain.
 
Everybody needs a 308. I always recommend having a 308 as a baseline. Everything else is just a bonus. Good luck!!!!
 
gumby510 said:
GLB how far/what distances do you shoot.
Click to expand...

This is a rifle I had built for hunting. I shoot/ practice out to 400 yds regularly. I shoot it along side of one of my 308s and it hits steel with authority.
 
GLB said:
I have a 708 with a 20" #4 Krieger barrel with a 9.5 twist. I shoot the Berger 140 VLD and it hammers. I would go with a 9 or faster twist if you wanted to shoot heavier than 140 grain.
Click to expand...

Depending on elevation 9.5 will likely do anything but the 175gr and longer bullets. I run a 1:10 twist and have no issues stabilizing 162gr Amax's.
 
RobertB said:
Everybody needs a 308. I always recommend having a 308 as a baseline. Everything else is just a bonus. Good luck!!!!
Click to expand...

X100000, I tell all my customers this when there asking about calibers.
 
Well its looking like if Im going to go through the hassel of rebarreling I might as well to 7mm08.

So a ss Bartlein barrel 7mm08, 1-9 twist, 5R rifling, REM varmint contour, 18.5-20in barrel length, threaded to 5/8x24.

Or

SS Bartlein barrel 308, 1-10 or 1-11 twist, 5R rifling, REM varmint contour, 18.5-20in, threaded 5/8x24
 
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I would go .308. There isn't a huge difference between the two with the exception of bullet/ammo availability, siding .308. If you plan on shooting subs get a 1-8". If not a slower will work. You can get out pretty far with a .308 but it's like chucking a cinder block.
 
Had my 308 our to 1273 last weekend. Went sub at 1200ish. Shot 2 ridiculous groups way out there under 10". .308 like others have said is a great 'baseline' to educate yourself with.
 
talk of huge differences is rubbish. comparing the crude ballistic curves exaggerates the benefits. ballistic advantage only reduces the errors you make.

If a 7-08 has 20% less wind drift you will have 20% less error. learning sound shooting skills will reduce errors by much more than sweating the ballistic advantages of any bullet out of what is essentially the same cartridge.

308 has practical benefits in terms of cheap ammo to learn to shoot with.

A good shooter with a 308 will kick the ass of a poor shooter with anything. Get the huge benefits from learning the skills then when you are trying to be competitive seek the marginal gains of a ballistically better cartridge. Inside the line is 1 point more than outside which is why 7-08 260 etc beat 308 with shooters of the same skill level. They are not massively better.

If shooting things, get a 308 as the 'higher energy' on target argument is only that - an argument. It is not validated fact
 
Chanonry said:
If shooting things, get a 308 as the 'higher energy' on target argument is only that - an argument. It is not validated fact
Click to expand...

Actually it is, because math.
 
gumby510 said:
Well my tikka is starting out as a 22in 308 if that is any consultation
Click to expand...

I've said it before and I'll say it again...

I shoot a local long range match with two of the most highly acclaimed firearms instructors in the world who both shoot expensive 308's.

They always finish towards the top of the heap but seldom win the match. Why is that? I guarantee you it's not because they are not highly skilled rifleman! The reason is... It's because they use a cartridge that has almost twice the wind drift as most of the rest of us. Simply put their chances of guessing their wind holds good enough to hit 1.5 MOA steels are significantly decreased in comparison to those shooting 6mm, 6.5mm, and 7mm.
 
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Not sure why all the negative vibes against the .308?? It is the parent case for many other great rounds!!! One of which is my personal favorite....the .260 Improved. Having said that...my .308 spits out 185 gr.VLD's right at 2900 ft/sec. from a 30" tube. That is respectable even in .30-06 circles. Having said that...my .260 Improved is sending 142 gr. pills out at just over 3000 ft/ sec. The .260 has half the windage and elevation of the .308. But where do you draw the line???? I'd take my 6.5mm pills over the 7mm any time. Having said that.....it's all personal choice. The .308 will still be my choice for deer sized critters. YMMV.......Again....It's intensely personal.

Wayne
 
There is no hating against the 308, it is just about the BC curve that is all, wind is a mother when shooting long distance and yes there are a lot of cartridges that are phenomenal that started from the 308. I have a 308 that shoots sub moa groups, but throw in a full value wind and I really have to work to hit my target at 800 to 1000 yards. Where as with my 338 Lapua totally different story because of the high BC, if you look at the different BCs the 260 Remington almost matches the 338 Lapua with less recoil. I will have to agree everyone needs a 308 so that they can learn off of it from a base line and then move onto a better round that makes it all come together.
 
im dumb and just dont know , 7mm-08 and 308 differences 18.5-20in barrel

I shoot a .580BC bullet at 2740fps in my .308. Why do I need .585BC Scenar-loaded 6.5 factory ammo at 2700?
 
im dumb and just dont know , 7mm-08 and 308 differences 18.5-20in barrel

Yup. JLK VLD in a stock 24" AE.
 
Your right about that, but a 7-08 with a .635bc @ 2770 is an improvement, and a lot of fun with good expected barrel life to boot.
 
im dumb and just dont know , 7mm-08 and 308 differences 18.5-20in barrel

Runamuk said:
Your right about that, but a 7-08 with a .635bc @ 2770 is an improvement, and a lot of fun with good expected barrel life to boot.
Click to expand...
I couldn't get the 180s to 2770fps in any 7-08. That high a BC with that high a velocity took a .284. What is your load that does this?
 
BoilerUP said:
Assuming the same barrel length and same weight bullet, the 7-08 will probably be 50-100fps slower than the 308 but the higher ballistic coefficient should make it fly flatter with less drift at extended ranges.

Big issue with a 7-08 right now, IMO, is Hornady's suspension of the 162s which many folks believe are more optimal for the 7-08's case capacity.

My opinion? Skip both the 7-08 and the 308 and spin up a 6.5 Creedmoor.
Click to expand...

I dunno...

My experience with 308 has been, with a 24-26" bbl, that a 168gr usually goes 2800-2850, a 175 goes 2700-2750 and a 180 goes 2500-2550.

And with 7mm-08, with the same 24-26" bbl, a 162 goes 2800-2850 and a 175 goes 2700-2750.

I agree that usually, a rifle case is more efficient at getting velocity out of heavy bullets when the bullet diameter is bigger, but at least in the case of 7mm-08 vs. 308, the 7mm version matches the "efficiency" of the larger 308.

I also agree the suspension of the 162s (amax and bthp) is a serious bummer to the 7mm-08 target shooters.

Nothing wrong with the 6.5 Creedmoor, but the OP has asked specifically about only the 7mm-08 and 308win.
 
I say .308 retains velocity very well when cut down. Nothing wrong with a 7mm-08 every time i look at .284 i want a .284 winchester or 7SAUM though.
 
I own a 308 and a 7mm-08, and I really like them both. The rifles are so different that I can't make a meaningful comparison (308 is full custom F-TR setup, and the 7mm-08 is a stock Steyr Mountain Rifle). That said, if I we're hell bent for leather to shoot a 7mm out of a short action I'd probably be looking at a .284 Win. Factory ammoseek may be tough to get a hold of, but you could always move up your plans rto start reloading.
 
The 284 doesn't perform overly well in a true short action. In a mid length like the FN actions that are WSM length tge do ok but nothing like the ones running in long actions. The same thing goes with the short mags as well, they have the capacity to run the the heavier slick 7's but they take up a lot of powder real estate in a short action.
 
Just built a 7mm Creedmoor for a customer with a 18.5" barrel for a customer and he is getting 2650 FPS with 42 gr of Varget and the 162 A-Max. Seems to be good performance out of such a small package.

Mark
 
Mgordon said:
Just built a 7mm Creedmoor for a customer with a 18.5" barrel for a customer and he is getting 2650 FPS with 42 gr of Varget and the 162 A-Max. Seems to be good performance out of such a small package.

Mark
Click to expand...

Is the barrel treated like some of the others you built?
 
Nortex said:
The 284 doesn't perform overly well in a true short action. In a mid length like the FN actions that are WSM length tge do ok but nothing like the ones running in long actions. The same thing goes with the short mags as well, they have the capacity to run the the heavier slick 7's but they take up a lot of powder real estate in a short action.
Click to expand...

The 284Win does not take a big hit in case capacity in a short action when COAL can be pushed out to 2.950" or so.

175s and 180s can be pushed to 2800-2850fps with moderate pressures.
 
That's closer to a mid length action. It will either require action work or a specific action. Some do not advocate modifying and existing action while some say it's no issue. I myself would rather have one made for the desired length.

What length barrel are the short 284 people running to get that velocity?
 
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