Velocity or Energy

[Stix]

G'Day all.

I'm trying to make a more informed decision for a hunting rifle and would like to hear peoples thoughts on the penetration power or high velocity vs high energy calibres/projectiles.

I primarily hunt large feral pigs in the 100-150kg range at 150-350 metres (soon to be 500m +) and need good penetration to hit running pigs and either smash large bones or leave a decent exit wound. I often shoot 10-15 rounds in 1-2 mins and so can't go much past a .308 recoil wise.

Most people will instantly say the larger calibre with heavier projectiles will have better penetration. At some point though a lighter but faster bullet with have more penetration. I have seen 22-250 punch through steel when a .308 wouldn't.

I know shooting steel is a lot different to travelling through 2" of mud and then 2 feet of flesh and bone.

Obviously bullet selection is critical but i use nothing but controlled expansion bullets with extremely high weight retention (Primarily Accubonds).

So at what speed would a 100-140gn pill have equal or better penetration to 180gn .308 at 2600?

Basically just looking to see if there is a smaller/faster/flatter calibre than my preferred .308 which will give equal or greater penetration for equal or less recoil?

 

[benchracer]

Unless you intend to use monometal bullets, I don't think speed is the answer to the set of problems that you have defined. I believe that sectional density, higher bc, and moderate velocity is the answer to your problem set.

I would be looking at 6.5 or 7mm chamberings in the 7x57/7-08 or 6.5x55/.260 class. Both offer bullets with better bc's and greater sectional density than the .308. Both will also fly flatter and reciol less than the .308. The 7's will offer greater flexibility in bullet weight than the 6.5's.

With either the 6.5 or 7's, you may find that premium bullets are not necessary. Both also retain the option of going with bonded bullets in the optimum weight ranges for each caliber/chambering.

 

[Greyfox]

I agree with Benchracers answer. John Taylor, an African hunter over a century ago had a similiar question and devised a "Knock out" formula for solids for use on big game. Overall ot took bullet diameter, weight, and velocity into consideration and proved to be a useful approach. It csn be loosely applied to bonded bullets to give a fairly good comparison. The formula is;

(Bullet diameter x velocity x bullet weight) / 7000 = knock out value

308. 180x2600x.308/7000= 20.6 KO
6.5. 140x2950x.264/7000= 15.6 KO
338. 300x2750x..338/7000=39.8KO
223. 69x3000x .223/7000= 6.6KO

Not perfect because bullet performance comes into play but itdoes speak to killing power and gives a comparison that applies multiple factors which is somewhat answering your question.

 

[liltank]

I have to agree, but what about using a 125-150 bullet in .308 running it at high velocity. I know that Barnes makes a smaller weight mono metal bullets. They have a 110, 135, and 150 grain bullet. Run them with a 24" or longer barrel with a healthy dose of H4895, IMR 4064, H335, IMR 4895, CFE223, Benchmark, XBR8208. All of these produce phenomenal velocities with light .30 cal bullets. I looked at some load data on the Hodgdon site and they are claiming 3350fps with the 110 TSX. That will get you out to you prescribed distances. If you want a little more weight, go with the 135's. That would get good penetration with weight retention. With my playing with Alliant Power Pro 2000MR, you should be able to get the 150's over 3000fps.

Not to mention the lighter bullet would reduce recoil too. I remember loading 110 Hornady V-max in my .308 was a joy to shoot.

 

[J E Custom]

It realy takes both and should fall within the bullets performance range.

I would kook at the 260 rem or the 7/08. both are based on the 308 and would be an easy
rebarrel job for your 308.

Both the 260 (6.5) and the 7/08 (284) have a great selection of bullets and will exceed 3000
ft/sec with the right bullet.

Recoil will be less and ballistics and velocity will be better.

When I competed in 500 meter running boar competition the preferred cartrige was the 7/08
for speed,accuracy and lack of recoil for follow up shots.

I have killed many 300+ pound pigs at 500+ yards and made many squeal beyond 800 yards.

With a 308 as the max you want, ether of these will do the job well and not require an extensive
re build.

J E CUSTOM

 

[barnesuser28]

I would go 7/08 with the 168 grain lrx, should get you out to about 600 yards before velocity is too low for expansion.

 

[HntWhtTail]

I recently met a guy that is developing a new cartridge that is exactly what you are looking for I will look for his card and get a link for you. what I remember is its a necked up 308 to .458(dont quote me on that), running on AR platform. they are getting close to releasing with pressure tests done, and accuracy and ballistics look good of course he is wanting to sell them so of course thats what he will tell people. I will follow up later on this.

 

[liltank]

I recently met a guy that is developing a new cartridge that is exactly what you are looking for I will look for his card and get a link for you. what I remember is its a necked up 308 to .458(dont quote me on that), running on AR platform. they are getting close to releasing with pressure tests done, and accuracy and ballistics look good of course he is wanting to sell them so of course thats what he will tell people. I will follow up later on this.

Would that be the 450 Bushmaster or 458 SOCOM?

 

[Stix]

Cheers guys, at the ranges i shoot i don't really see a huge differance in a 7mm08 over .308. As stated you can load light bullets in a .308, can't load heavy bullets in a 7mm. Trajectory may be better out over 500 but that means little to me.