Decisions - 308 or 7mm08 in Gas Gun

[5soutdoorsTX]

So.... Proof Research just sent some 1/8 twist CF barrels to their Texas distributor (I'm a newsletter recipient). I had previously been thinking of a larger bore caliber to use for OK/NM/TX elk, mule deer, and for nilgai hunting in South Texas.

I already had a 308 Barrel that I was eyeballing using for that task. 18" in length. Also have a 12.5" 308 barrel... But I have been talking with a friend who built a 20" 7mm08 that he uses for pig killing in Central Texas as well, and it got me to thinking.... What about just doing a 7-08 16 or 18" instead of 308.

So here I am... trying to figure out, which might be the best option. the 8 twist 308 will be capable of shooting subs, but also 170-180gr mag length 308 loads, including the new Hammers. I was going to have to purchase a special order 7-08 barrel from XCaliber in carbon fiber with a faster twist as well, so the cost of the barrel not a factor in determining the barrel option. The biggest question, to me at least, is which would be the most ideal to shoot.

Which would you pick, if you were using a gas gun for the above scenarios? Longest ranges would be on the Elk and Mule Deer populations 300+ yards. Our south Texas Nilgai are generally within 150 yards. No subsonic shooting at all, just true brute terminal ballistics with heavier projectiles.

 

[Shurefire]

With ranges that short I would think either cartridge would work great. I would pick the one I have equipment to load for and go with that. For me, that would be .308.

 

[Loudenboomer]

It's hard to argue against a .308. The Ar-10 gold standard. That being said I have an X-Caliber 7-08 barrel. I set my gun up with 22" and a +2" gas tube with a SA adjustable gas block. I went with a 1-8 twist because I primary shoot 180 gr VLD bullets. We don't have wild hogs up here but I imagine it would anchor oinkers just fine.

 

[5soutdoorsTX]

It's hard to argue against a .308. The Ar-10 gold standard. That being said I have an X-Caliber 7-08 barrel. I set my gun up with 22" and a +2" gas tube with a SA adjustable gas block. I went with a 1-8 twist because I primary shoot 180 gr VLD bullets. We don't have wild hogs up here but I imagine it would anchor oinkers just fine.

What sort of velocity are you getting with your 180gr loads?

 

[5soutdoorsTX]

With ranges that short I would think either cartridge would work great. I would pick the one I have equipment to load for and go with that. For me, that would be .308.

I agree... I don't load for either yet, but the idea would be I would be since the goal is to load the heavier, non-typical projectiles. Most of the factory ammo is geared for slower twists.

 

[Loudenboomer]

I've been using StaBALL 6.5 powder. burn rate bit slow for this platform but have been able to tune for it. Hogdon data shows 40.9 to a max of 46.0 gr. and 2669 for the 175 gr Nosler partition. I was using LC brass and reached max at 43.5 with the 180 VLD at magazine length. I did not chronograph but I suspect a little south of 2600 fps. As always work up carefully. Safe in my gun YMMV.

 

[searcher]

I have an M1-A in .308 and a Browning BAR in 7MM Rem Mag, neither similar to what you will be working with, yet the 7 MM-08 is just a tad slower than the 7 Mag (150 fps?) and would shoot the Barnes TTSX bullets with better flight characteristics and better penetration, I think, than the .308. Not a problem at all on pigs (I recently shot a 120 TTSX completely through two pigs and both were DRT). But for shooting Elk-sized critter, I'd up the bullet weight to a 150 and feel I'd have the penetration of a 180 grain lead bullet in either caliber. For pigs, whitetails (or the occasional coyote) the 120 TTSX is incredible. The 7MM is the better option for going down in bullet weight when wanted - whereas the 30 cal is not quite as flexible with good bullets. The .30 is great for the larger animals - maybe marginally a bit better?

Either of those would work fine - if you already have dies or components of one - I'd just pick what will cost you the least to set up for reloading. If I had no components or dies and plan on most Texas-type game - I'd opt for the 7mm-08, though for no overwhelming reasons. I do like the smaller bullet option when shooting smaller animals and reduced recoil that accompanies it as I don't have brakes on those guns. like to see hits.

 

[mattri]

Either is a great choice. I built a 7mm-08 a few years ago and was very happy with it. Having said that I now shoot a 308- the ballistics are similar enough with the 140-160 bullets I would use in the 7 but the versatility of the 308 wins in that category plus the availability of components, ammo etc pushed me to the 308 and I am happy with my choice. Good luck and keep us posted.

 

[SteveOak]

You may get better answers in the hunting forum.

 

[Adam in WI]

I did an 18" 1-9 twist 7mm-08. My thought process was that twist should stabilize up to ~168 grain bullets. Any heavier would be wasted when loaded to mag length in an AR IMO. It's currently for sale in the classifieds here (shameless plug). I'm not sure I'm sold on the large frame auto.

 

[DiffEQ]

I did an 18" 1-9 twist 7mm-08. My thought process was that twist should stabilize up to ~168 grain bullets. Any heavier would be wasted when loaded to mag length in an AR IMO. It's currently for sale in the classifieds here (shameless plug). I'm not sure I'm sold on the large frame auto.

I built a 7mm-08 with a Wilson Combat 18".
I chose it over 308 because the ballistics and energy are better past 400.
I ltypically load Lehigh 127gr monos and Hornady 162 gr interlocks.
It's not for sale.
The only thing I would change is the handguard, which was a M5E1 hybrid quad rail.
I have since built an 18" 308 because I got a matched upper/lower and barrel for stupid cheap. I still prefer the 7mm-08.

 

[Adam in WI]

Time will tell if mine sticks around. Maybe I put a carbine stock back on and a lower power scope. I could load some light monos for the girl to use. A little more horsepower than .243 wouldn't hurt...

 

[5soutdoorsTX]

Welp, decided to go ahead and stick with the 308 barrel I had... and then went and bought a 22creedmoor barrel. Jus tin time for 25creedmoor casings to be announced. Just my luck. Guess I'll just have to build some more uppers.