Favorite caliber in the AR platform and why?Or what caliber do you hate and why?

[Twodogs]

I am loving the idea of .400 Legend, so I will be doing my best to try and help it take off. It is on the short list of builds for the near future, and then I will show it off to as many people as will listen.

I've got a couple of 6.8 spc rifles so just a barrel swap and I would be up and running.

 

[lucusloc]

Why not just use .308? .400 legend is 1000 fpe at 225 yards vs .308 out of a 12.5" barrel is 1000fpe at 425 yards. Longer barrelled .308 would be even farther (Fe 18" would be 575yds). Is the attraction just due to lighter weight rifle?

The attraction (for me) is the bigger bullet. Most of these big bore cartridges are not for long range performance, as many of them are optimized for sub 100 yard ranges. We already know that to optimize for long range you want a long, skinny bullet with maximal sectional density, but that optimization minimized other desirable qualities like "brush busting" over short ranges. A long skinny bullet is going to have it's terminal performance impacted to a far greater extent over, say, 25 yards through brush than a perfectly spherical bullet (which is the ideal brush busting shape). A short, fat and heavy bullet is much closer to that ideal than a long pencil thin bullet.

This means that a short fat bullet is going to be just about as effective after hitting a small branch as it would have been had it received no such interruption, whereas a longer thinner bullet might not even make it to the target in one piece given the same interruption.

Of course all this is assuming something akin to solid shot of course, once we get into engineered bullets that require a specific orientation and spin for proper terminal performance no amount of bullet proportion is going to help you after you hit an obstruction. As always know what you are facing and choose a bullet technology to suit.

Then there is just the raw appeal of big bore cartridges. They are super fun to shoot, often have milder perceived recoil for the same energy (due to the longer recoil impulse) and offer a very satisfying "Thump!" when they impact a target. They may not be as versatile or as well rounded as more modern cartridge paradigms, but they do have a niche to fill, and one that has been long neglected to boot (since just about the end of the black powder days).

I've got a couple of 6.8 spc rifles so just a barrel swap and I would be up and running.

Do it. We need more people running all the new big bore cartridges.

 

[ilikegunspdx]

The attraction (for me) is the bigger bullet. Most of these big bore cartridges are not for long range performance, as many of them are optimized for sub 100 yard ranges. We already know that to optimize for long range you want a long, skinny bullet with maximal sectional density, but that optimization minimized other desirable qualities like "brush busting" over short ranges. A long skinny bullet is going to have it's terminal performance impacted to a far greater extent over, say, 25 yards through brush than a perfectly spherical bullet (which is the ideal brush busting shape). A short, fat and heavy bullet is much closer to that ideal than a long pencil thin bullet.

This means that a short fat bullet is going to be just about as effective after hitting a small branch as it would have been had it received no such interruption, whereas a longer thinner bullet might not even make it to the target in one piece given the same interruption.

Of course all this is assuming something akin to solid shot of course, once we get into engineered bullets that require a specific orientation and spin for proper terminal performance no amount of bullet proportion is going to help you after you hit an obstruction. As always know what you are facing and choose a bullet technology to suit.

Then there is just the raw appeal of big bore cartridges. They are super fun to shoot, often have milder perceived recoil for the same energy (due to the longer recoil impulse) and offer a very satisfying "Thump!" when they impact a target. They may not be as versatile or as well rounded as more modern cartridge paradigms, but they do have a niche to fill, and one that has been long neglected to boot (since just about the end of the black powder days).


Do it. We need more people running all the new big bore cartridges.

Weird. I don't see the benefit of brush busting, I would think the opposite due to bullet width and bullet shape. Nor do I see a perceived recoil benefit but I've never shot that round. Only benefit I could see would be if you were hunting whitetail etc. at short range in a state that restricts hunting to straightwalled cartridges and that also have a maximum cartridge length restriction.

 

[lucusloc]

Weird. I don't see the benefit of brush busting, I would think the opposite due to bullet width and bullet shape. Nor do I see a perceived recoil benefit but I've never shot that round. Only benefit I could see would be if you were hunting whitetail etc. at short range in a state that restricts hunting to straightwalled cartridges and that also have a maximum cartridge length restriction.

If you were staring down a 300lb boar through 15 yards of heavy brush, and he suddenly decides to charge you, are you going to want a gun that shoots some 6 or 6.5 mm javelin that might arrive at the bore in multiple pieces, each of which are small enough they may not even penetrate the skull, or would you rather have one that shoots some .40 or .50 cal monster that could blast through a 1 inch branch, arrive at the boar backwards and tumbling, and still penetrate deep enough to shut down the boiler box right now?

Again, these are not general use cartridges. The modern paradigm of thin and long has much more versatility and capability than big bore stuff. But in the places where you need it, you need it.

I do own a lot of stuff that fits both paradigms. They do shoot different, and have a different character for both fun and serious use. A lot of people who shoot big bore for the first time with me wind up loving it, and will pick one up even if they never plan on getting into those niche circumstances where they really shine. They are just plain fun to shoot.