7mm08 vs .308

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7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:45 am

secondtry wrote:NOTE : this is not a thread hijack, but I'll start a new topic if it turns into a hijack :lol:

Regarding a mild mannered long range whacker, such as the 308 with loads and target related projectiles that have been discussed here, what are the thoughts on the 7.08 using the 150 ELDX as a milder mannered path to similar results ? For me frontal area is hard to trump, but we are not talking about big animals.



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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:48 am

stokesrj wrote:I think the 7mm-08 will do a little better on the wind, but otherwise not much different other than the .308 has a little bit more mass which can be important when using fragmenting bullets. This guy Nathan Forster, a Kiwi fellow, uses both the 7mm-08 and .308 for long range, what he calls hack rifles (non glamorous, work rifles) and then pairs them with a magnum when conditions call for it, beyond 800 yards, or more difficult wind conditions.

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:49 am

Thanks Secondtry, I've just waded in to reading up on 7mm08 vs .308 Ballistics remembering that kiwi's have a peculiar affection for this round for both in both the North Island for shots at sneaky sika deer and on the south for tahr.

If you believe what's easily found on the net the 7mm08 with a 160 at 2700 has a whopping 84 fp kinetic energy advantage with 4 more inches less drop and wind drift at 600 yards than a 165g from a .308 at the same muzzle velocity. Oh, and that 5g difference in bullet weight gives you 17.18 foot-pounds free recoil against 17.94 f-p in a 7lb rifle....

Now, if you are going to buy a Remington Titanium / Alaskan (whatever their ultralight is now called) or a Kimber Mountain Ascent you'd be hoping the accuracy node with 160g projectiles in the 7mm08 is at 2700fps rather than 2600fps or the above is negated, but hey, at least it will kick less than a .308 :ugeek: :lol: :lol:

To my mind it's once again a situation of comparing cartridges of similar volume throwing similar weight bullets where there is a difference in mean velocity between the two but the SD of velocity overlap. So you have a choice of a) if you picked the faster round you better hope your rifle shoots mean velocity or faster accurately, or b) convince yourself that frontal area is the most important factor on game, or c) convince yourself that if you loose your ammo on a hunt in Poofter's Froth Wyoming they'll have a box of ammo that shoots well in your rifle at the general store because you went with the popular round :lol: :lol: :lol:

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:49 am

SPEEDY wrote:Would that mean that my 308win load of a 168gn Zmax at 2800fps would beat their top 7mm/08 load?

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:50 am

SPEEDY wrote:Would that mean that my 308win load of a 168gn Zmax at 2800fps would beat their top 7mm/08 load?
Yep, but I'd say it also recoils more :lol:

Now here's a question; does the extra steel in a 7mm08 barrel of the same profile barrel as a .308 make up for the difference of say 5g per bullet in a fully loaded magazine making both a .308 & 7mm08 R93 weight the same, and hence make the recoil comparison valid :think: :liar:

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 3:50 am

secondtry wrote:Lost my post - again :(

GBE - the only place that you will get 2700 from a 160 out of a 7.08 is on the internet.

I have loaded for two 7.08s and 2600 with 160s was a hard stretch. It seemed to me that achieving claimed bullistics was easier with the 308 than the 7.08.

The 308 may be a simpler path to the LR goal but the 150ELDX (and maybe the 150LRAB) piqued my interest in the 7.08 as a lighter recoiling alternative to the established 308. I'd be hoping for 2700 from either of those projectiles - not much different from what could be expected from a 168g 308 load.

And yes, the 7.08 does, in general terms, recoil less than the 308; although that is a question that can be bullistically manipulated to provide whichever answer is desired. Shooting a lightweight rifle in either calibre, prone, over a pack, the 7.08 is nicer - recoil wise.

Certainly tahr, chamois, and reds are toast for either with appropriate projectiles, and high BCs should stretch the toasting range quite a bit. 500yds would be plenty for my skill level - well within the 600/800 envelope referred to by Bob and Nathan Foster.

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 4:00 am

A sure fire way to reduce recoil of a .308 is to reduce the loads, and if you do that then the bc advantage of the 7mm might shine through at equal velocity, after 500m :D

Barrels are often laws unto themselves - I have a .308 in the safe that loves 180g pills at 2500fps, wont shoot 150s or 165s to save itself, it might shock me if I tried Speedy's pet load but I doubt it. I also have to laugh when reading 7mm08 advocates claim it surpasses the 7x57 by 100fps accross the board - the only way that can be true is if you restrict the larger case to 1893 pressure levels

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Re: 7mm08 vs .308

Post by SPEEDY » Fri Dec 08, 2017 4:11 am

My load is 43gn of ADI BM8208 which is .3gn under their max listed load that is supposed to only develop 2707fps from a 24" tube.
So with .3gn less powder and 1" less barrel I get 90fps more recoil.
I don't know if its the Lapua cases or the barrel, but thats what I get and its consist.
I'm soft and I don't care. :dance:

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 5:20 am

hmm, another powder to add to my collection :dance: :lol:

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Re: 7mm08 vs .308

Post by stokesrj » Fri Dec 08, 2017 7:12 am

There is another important consideration when comparing these two calibers. The .308 has a longer freebore. I’m not positive this is the case for Blaser barrels in 7.08 as I’ve never measured one but in several .308s I’ve been able to exceed book loads by up to four grains of powder using H4895 with safe, smooth operation and long case life. The opposite was true with the only 7.08 I owned, a Kimber 84 Super America. It began exhibiting high pressure signs, heavy bolt lift, flattened primers and ejector marks, at a full grain below book max. That particular rifle had a very short throat that allowed the bullets to contact the lands before reaching magazine length for several bullets I tried.
I’ve been able to push the 168 grain ELD-M out of my current 20” .308 at over 2700 FPS at safe pressures. In this application, short handy long range rifle, I would choose the .308. But if I were looking to build a light long rifle for long range use, I would choose the 7.08 over the .308 but I would choose a 7mm Rem Mag over either If going for a 24” barrel or longer.
Robert J Stokes

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Re: 7mm08 vs .308

Post by SPEEDY » Fri Dec 08, 2017 8:00 am

I kind of like the 308win for several reasons, its not exciting or different, its just simple and it works.
It uses a huge slection of bullet weights that are right for any game or occasion.
Its easy to load for or find a factory load that works.
It works in short and long barrels.
Its a plain Jane and unexciting round but it does it all without a fuss.
I'm soft and I don't care. :dance:

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Re: 7mm08 vs .308

Post by canalrifle » Fri Dec 08, 2017 4:54 pm

Speedy, I like your summary of the .308, it applies equally well to the 30/06.

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 6:24 pm

Gun Barrel Ecologist wrote: To my mind it's once again a situation of comparing cartridges of similar volume throwing similar weight bullets where there is a difference in mean velocity between the two but the SD of velocity overlap. So you have a choice of a) if you picked the faster round you better hope your rifle shoots mean velocity or faster accurately, or b) convince yourself that frontal area is the most important factor on game, or c) convince yourself that if you loose your ammo on a hunt in Poofter's Froth Wyoming they'll have a box of ammo that shoots well in your rifle at the general store because you went with the popular round :lol: :lol: :lol:
I have to quote the above after looking at another forum and reading a 2 page thread where someone has asked if he should use a borrowed .416 Rem or his .404J. I'm tempted to post "use a .416/500 double with 450g Norma PH ammo" but that would just be me being facetious whilst showing my tendency to embrace the obscure and treat c) with contempt :lol: :lol: :lol:
Perhaps that is why my 7x57R has killed more head of game than the .308 that sits opposite it in the safe :think: :ugeek:

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Re: 7mm08 vs .308

Post by Gun Barrel Ecologist » Fri Dec 08, 2017 6:41 pm

stokesrj wrote:There is another important consideration when comparing these two calibers. The .308 has a longer freebore. I’m not positive this is the case for Blaser barrels in 7.08 as I’ve never measured one but in several .308s I’ve been able to exceed book loads by up to four grains of powder using H4895 with safe, smooth operation and long case life. The opposite was true with the only 7.08 I owned, a Kimber 84 Super America. It began exhibiting high pressure signs, heavy bolt lift, flattened primers and ejector marks, at a full grain below book max. That particular rifle had a very short throat that allowed the bullets to contact the lands before reaching magazine length for several bullets I tried.
I’ve been able to push the 168 grain ELD-M out of my current 20” .308 at over 2700 FPS at safe pressures. In this application, short handy long range rifle, I would choose the .308. But if I were looking to build a light long rifle for long range use, I would choose the 7.08 over the .308 but I would choose a 7mm Rem Mag over either If going for a 24” barrel or longer.
I'm sure long throated 7.08s exist somewhere, surely the 2700fps claims arent all just internet fake news. In a 5.5lb rifle the marginal decrease in recoil for little loss in ballistics is probably worth it. There was a claim by Roger Lentle in one of his numerous books on hunting in NZ that a 150g bullet was the effective minimum for tahr in full winter coat. The 7.08 sneaks in the .260 falls short but then again you could always just hunt spring and summer :think:

I see Kimber are offering their mountain Ascent in 6,5 Creedmoor at 4lb 13 oz, shame it'd be no good in winter according to one author :lol:

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Re: 7mm08 vs .308

Post by stokesrj » Fri Dec 08, 2017 7:05 pm

I’ve built several really light weight rifles and enjoyed climbing with them but as I have become experienced I want more of a sturdy medium weight rifle even for those long climbs. Those mid weight rifles are just plain easier to shoot well with at long range. Now days if I want really light the K95 fils that bill nicely. I’ve sold off most of my super light weight rigs in preference for the mid weights.
Robert J Stokes

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