7mm or 30 cal? Just for curiosity’s sake

[CBH Australia]

@Calamity post is certainly valid, so are the responses.

I've had a few .308's go through my hands.
I have one .300wm, my 2nd one.

I have had great success with my Tikka CTR 7mm-08

I built a .280ai on a whim. Someone suggested it I researched it and my gunsmith assembled it.

I used a 7mmRM in Africa because I had never used one it was pick of the hire rifles. I went well with it. But I think my .280ai will do well with the 26" barrel and handloads.

In short those rifles iisted are

My Truck rifle

My Hunting rifle (Bear rifle)

My Mountain Rifle

I have a Bunny rifle, a spotlighting rifle, a .308 for my general hunting (pig shooting), we can call that a Pig gun I guess. A Varmint rifle .22-250
I have a 375H&H as my Elephant gun.

Now, I don't really hunt bear or Elephant. I would like to Hunt Buffalo, Lion Bear one day

Australia come up short in the huntable game department from day dot. Our natives animals are protected species so not considered to be huntable but we can hunt introduced species such as Feral pigs in many areas. There are introduced Deer, foxes, rabbits and goats.

Anyway, back to the debate.

 

[UCzO___]

You have gotta think in terms of surface area

A circle with a .308 diameter has 15% more surface area that a circle with a .284 diameter.

My experience is not as prolific as some here, but on dozens of moose and elk I have seen the 30's hit harder and create more trauma.

Shot placement and Bullet performance are however the two most important factors when it comes to terminal performance, so I get what you are saying - how much of a difference is .024" really going to make?

The answer is 'some'

I am NOT a LR hunter, but I did the math on the SD. Since diameter is in the denominator, given the same Mass, the 7mm has a higher SD. Just saying. If I can get my 7mm projectile moving at the same velocity as your .308, I think the terminal performance would be...

 

[Calvin45]

I am NOT a LR hunter, but I did the math on the SD. Since diameter is in the denominator, given the same Mass, the 7mm has a higher SD. Just saying. If I can get my 7mm projectile moving at the same velocity as your .308, I think the terminal performance would be...

You're right for sure...but the thing for me is i like my 208-230 grain 30 cals. There are no 7s of equal weight.

 

[Mustang72]

30 cal for me! Nothing wrong with 7s though.

 

[Calvin45]

You're right for sure...but the thing for me is i like my 208-230 grain 30 cals. There are no 7s of equal weight.

But it if a person has no plans to shoot anything over 180 grain this 30 enthusiast would advise them to go 7mm.

 

[dxlbaile]

This is like asking the question , There are two sexy sisters. Which one should I date?? You already know the answer.. Date em both!
I have a 7mm rem mag, 28 Nosler, 300 Win.. They are all awesome for different reasons, and very much alike in many ways.. You didn't say you could only have one gun.. One of each. JMHO..
Then in the end you could make a 7-300 and call it a day..

 

[Hand Skills]

I am NOT a LR hunter, but I did the math on the SD. Since diameter is in the denominator, given the same Mass, the 7mm has a higher SD. Just saying. If I can get my 7mm projectile moving at the same velocity as your .308, I think the terminal performance would be...

Yes, just remember, we are talking about projectiles that deform on impact (i.e. expanding bullets). I think SD applies better to wound theory in the case of NON EXPANDING SOLIDS.

Here is an interesting read;

Terminal Ballistics

 

[358 Guy]

All things being equal, a wider bullet means a wider wound channel. While there are many other variables, this remains a constant.

 

[Calamity]

UCZO: Thanks for your comment of cross section area. Intrigued by your post, I calculated the difference in cross-section area and found that it is 0.011 square inch. That is the diameter if a straight pin. A pencil lead is four times larger. I don't think that is significant enough to make a difference.
Hand Skills: Thanks for the graph table. That is helpful. It looks like the two calibers produce similar size wound channels (50mm) if the bullets are the same mass and velocity (175/180 gr@2880-2920 fps). So, Calvin45 has a point, too, the heavier 30 cal bullets (220 gr) produce wider wound channels, and it probably has to do with bullet construction and the lengthier bullets having more mass to produce a larger mushroom. That is fairly obvious if one thinks about the difference in energy say between a 750 gr .50 BMG round and a 50 gr .223 round both traveling at 2800 fps. But what would a 750 gr .223 round do? It would be a lead arrow, and if it were soft lead, it would likely exit the animal the size of a soft ball. Anyway, my supposition was, and remains, that 7mm and .30 cal bullets of the same weight and impact velocity should perform pretty much the same with regard to terminal effects on game, assuming equal bullet design. The 7mm would have a higher SD, and likely have greater penetration, but both should produce very similar degree of wounding, shot placement being equal. It would be instructive to find out if bullets of equal SD would behave the same. It would be interesting to test this in gelatin or potters clay.

 

[WahooYahoo]

284

 

[MagnumManiac]

The only part of this debate that's stays constant is Sectional Density.
BC is not constant. Twist rate and Velocity play a part in final BC.
Even though I voted 30, my all time favourite cal is, and always has been, 6.5mm. Cut my LR teeth with a 6.5x55 Swede on a sporter Mauser 96. We shot comps at 300/400/500/600 every second Saturday. That rifle, with it's Carl Gustav 4 groove 1:7.25" twist was exceptionally accurate.
Anyway, the BC out of a 30-06 is different than it is out of a 30-378 Bee. Period.
If you think this statement is false, then shoot the SAME bullets 400fps faster/slower and tell me what the dopes work out to be.
BC's quoted are given that number in a velocity window, go above or below that window and the BC changes.
This is why many believe Nosler had it wrong for so many years, they didn't, it was just their velocity window was higher than most mainstream cartridges produced.

Cheers.

 

[358 Guy]

A 175 gr. 7mm bullet has a S.D. of 310. A 30 caliber would need to weigh 205 grains to match the 7mm S.D.. Now assuming the bullet construction is identical, and the impact velocities are the same, which of these bullets has more potential lethality on game? The 30 caliber has more bullet weight, thus it will have more ft. lbs of energy, and it has more frontal area. If using the S.D. as the constant, the math tells us that the 30 caliber has the greater potential to produce a quick kill.

 

[Paladin300]

The only part of this debate that's stays constant is Sectional Density.
BC is not constant. Twist rate and Velocity play a part in final BC.
Even though I voted 30, my all time favourite cal is, and always has been, 6.5mm. Cut my LR teeth with a 6.5x55 Swede on a sporter Mauser 96. We shot comps at 300/400/500/600 every second Saturday. That rifle, with it's Carl Gustav 4 groove 1:7.25" twist was exceptionally accurate.
Anyway, the BC out of a 30-06 is different than it is out of a 30-378 Bee. Period.
If you think this statement is false, then shoot the SAME bullets 400fps faster/slower and tell me what the dopes work out to be.
BC's quoted are given that number in a velocity window, go above or below that window and the BC changes.
This is why many believe Nosler had it wrong for so many years, they didn't, it was just their velocity window was higher than most mainstream cartridges produced.

Cheers.

What you say is true. I too like the 6.5s but I am not a fan of the extreme overbore cartridges. While it is true that SD is what matters, in order to obtain the same BC and performance in the 6.5s and 7s you get out of the 30s and 338s you have to go extreme overbore which results in a rapid loss of barrel life. For example, the 30-06 vs the 30-378 you mentioned, you get five times the barrel life with the 06 as you do with the 378. That extra velocity and extra BC come at a considerable cost in efficiency. My last 30-378 took 115 grains of H50BMG to perform at the same level as my 338 RUM, which out performs the 30-378 by several hundred yards because of extremely heavy, high BC bullets and does it with 85.5 grains of R23. By going up in bullet diameter you are able to accomplish similar task more efficiently, place more weight and energy on target with slightly, though often significantly better wound channels. Again, the smaller bores fly flatter inside a 1000 yards but the bigger bores hit harder.

As far as recoil goes, a 7mm shooting a 180 grain bullet will in theory recoil harder than a 30 cal shooting the same weight bullet at identical velocities. It is a matter of physics. It takes more energy to accomplish the same task with the smaller diameter bullet. The smaller bores recoil less because most often they are shooting a lighter bullet. IMHO recoil management has a lot to do with the weight of the rifle, the construction of the rifle and the stock more than the caliber when shooting identical bullet weights at identical velocities. I understand the argument for the 7s but I believe for LRH purposes on large and dangers game the 30s do it more effectively and efficiently.

All that said, I prefer the 7mm-08 and 284 over the 308, but I prefer the 300 WM over the 7mm Rem Mag and I prefer the 338 Rum over the 300 WM. The longer the range and the bigger the critter, the bigger the gun.

 

[MagnumManiac]

Paladin300.
I don't sweat the recoil or even consider it when choosing a cartridge.
I sho my 10.5lb 375 Bee from prone and it does not have a brake on it.
In fact, the only rifle I own with a brake on it is my 338-416 Rigby Improved. It needs one.
I wouldn't say I like recoil, but I have no problems with shooting my 416 Rigby or 458 Lott off a bench, the only rifle I have owned that was brutal was my 9lb 505 Gibbs. 600g bullets at 2350fps was too much for me. Needed to be 12lb minimum to tame that recoil.
My 500 Nitro double is a pussycat shooting 570g @ 2150fps in it's 15lb weight range.
Recoil pulse has a lot to do with felt recoil.
My 7STW feels sharper than my 300WM, both Sendero rifles and weigh virtually the same.

Cheers.