Rebarrel to fast twist 270 Win or go 6.8 Western?

[83cj-7]

I have no interest in talking energy or whatever but I do have insight into the OPs original inquiry.

I have built two fast twist .270 Win rifles. Why? Well, I wanted to. One was an 8 twist Brux at 25” on a Remington 700 and the other was a 8 twist Carbon Six at 21” on a Kimber 84L Montana. The 25” pushed the 165 ABLR at 3000 FPS and was a legit 1/4 MOA gun at 700 yards. The 21” pushed the 165 ABLR at 2750 and was easily 1/2 MOA. I consider the ABLR to be one of the best killing bullets I have used in all calibers I have tried it in. That said, I’ve never shot an elk with one, just 50 or so deer.

Hope this helps the OP

 

[MarkOrtiz]

You are obviously set on ft lbs as a deciding factor. The 6.8 will shoot heavier bullets faster and give you more ft lbs. I would buy a new rifle and keep the 270 how it is for sentimental reasons.

 

[TaperPin]

Like it or not, understand it or not, live by it or not, the fun thing about ftlbs is it is quite literally the official nerdy measurement of work potential, and it works.

Other projectiles outside of ftlb recommendations, like the 77 gr TMK, or an arrow, also obviously kill animals, but rather basic cup and core bullets in plain boxes sold to your gramps in his hay day, or right off the shelf today, simply work rather reliably based on ftlbs.

It’s actually kinda silly to argue against ftlbs, but it’s also not wrong to say in addition to ftlbs, this other cool thing also works.

Having said all that, I’ll vote for more ZAP-BANG-POW! over less. Lol

 

[mlevimadden]

You’re not controversial, you’re just generally wrong.

I can tell Lou has an engineering background from his posts, and nothing he said was blatantly wrong. I honestly don't think he and Form are even disagreeing on the subject. Both of the following statements are demonstrably true:

1) Lou's point - The kinetic energy of a bullet (KE =1/2 m*V^2) is an accurate metric for the maximum amount of work a bullet can do. This is why a 300 gr 338 match bullet dumping all of it's energy into the vitals of an animal has the potential to create more tissue damage than a 75 gr 223 match bullet. I'm not saying it's necessary (based on pictures of the 223 thread), or that you could even find an animal that's chest cavity would stop that 338 bullet, but it is a very basic principle of physics that is well proven.

2) Form's point - Kinetic energy alone is not a helpful measure of tissue damage created by bullets. Bullet construction and impact velocity are more useful metrics (as noted by Form above for ballistic tests) for determining how a bullet will behave in tissue. This is why bullet manufacturer's share this information and list impact velocities rather than energy.

And a bonus demonstrable statement to prove I'm not just taking the side of the Fudd crowd:

3) 1,500 ft-lbs of kinetic energy is not a requirement to generate enough tissue damage to kill big game. There are multiple examples in the 223 thread of members having bullets generate more than enough tissue damage to quickly kill any animal in North America down into the 300-400 ft-lbs range of energy.

 

[atmat]

I can tell Lou has an engineering background from his posts, and nothing he said was blatantly wrong. I honestly don't think he and Form are even disagreeing on the subject. Both of the following statements are demonstrably true:

1) Lou's point - The kinetic energy of a bullet (KE =1/2 m*V^2) is an accurate metric for the maximum amount of work a bullet can do. This is why a 300 gr 338 match bullet dumping all of it's energy into the vitals of an animal has the potential to create more tissue damage than a 75 gr 223 match bullet. I'm not saying it's necessary (based on pictures of the 223 thread), or that you could even find an animal that's chest cavity would stop that 338 bullet, but it is a very basic principle of physics that is well proven.

2) Form's point - Kinetic energy alone is not a helpful measure of tissue damage created by bullets. Bullet construction and impact velocity are more useful metrics (as noted by Form above for ballistic tests) for determining how a bullet will behave in tissue. This is why bullet manufacturer's share this information and list impact velocities rather than energy.

And a bonus demonstrable statement to prove I'm not just taking the side of the Fudd crowd:

3) 1,500 ft-lbs of kinetic energy is not a requirement to generate enough tissue damage to kill big game. There are multiple examples in the 223 thread of members having bullets generate more than enough tissue damage to quickly kill any animal in North America down into the 300-400 ft-lbs range of energy.

Re: #1 — but no one has argued kinetic energy isn’t real or part of basic science, or that heavier objects going faster don’t carry more energy. We’re arguing it’s a useless metric for measuring killing ability.

It’s not some fancy theoretical conversation.