Federal 6.5 Backcountry?

[diverc18]

I don’t know about you guys, but I’m more excited about the 153tmk being available in factory ammo than the velocity gain since I don’t reload and live in a state where you can’t order/ship ammo. I definitely not sad about the extra velocity gain either though lol. I may or may not have already sent my barrel to be chopped because of it.

 

[wyosam]

Margin of error for a young shooter. The whole discussion was initially based on a 12 year old...and the 6.5Creedmore bunnies turned it into something about them...as adults, who have hunted for years and probably killed several big game animals.

How much energy is required to make up for each inch of miss in this “margin for error”? I assume there is some initial requirement to make up for the .022” additional miss one accepts for not shooting a more appropriate adult sized cartridge?


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[Aussie Dan]

It has everything to do with a 6.5CM being in inappropriate for elk hunting until now

Are we really beating this dead horse again?
Its been proven, with pictures and necropsies that elk have fallen to much smaller calibres than 6.5 creed.

 

[bnewt3]

I think something we’re not considering is the blast and concussive force at the muzzle.

Take this from a guy who believes in suppressors. I believe that if I’m polite enough to put a muffler on my car, I should put one on my firearm.

That being said, the inherent problem for many will be that concussive force.

If you push higher pressure out of a shorter muzzle/barrel length (I’ll assume that a large measure of the “why” for the shorter barrel is to run suppressed while maintaining an overall package length that is handy enough to run around in the wild with), it begs the question whether the longer barrel at lower pressure or the shorter barrel + can + higher pressure equates to an overall improved operator experience.


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The YT video Backcountry Hunting Podcast put out shows this. He had a 22", 20" both suppressed, 17" unsuppressed......17" blast was serious.....and thats just what related through the video.

I would have liked to see what blast was like compared to brass though.

 

[Andouille]

I think something we’re not considering is the blast and concussive force at the muzzle.

Take this from a guy who believes in suppressors. I believe that if I’m polite enough to put a muffler on my car, I should put one on my firearm.

That being said, the inherent problem for many will be that concussive force.

If you push higher pressure out of a shorter muzzle/barrel length (I’ll assume that a large measure of the “why” for the shorter barrel is to run suppressed while maintaining an overall package length that is handy enough to run around in the wild with), it begs the question whether the longer barrel at lower pressure or the shorter barrel + can + higher pressure equates to an overall improved operator experience.


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Fair point perhaps for magnums, but is muzzle blast/pressure on a short suppressed 6.5CM an actual concern, and how does overall rifle length factor into "operator experience? I run a 19" barrel 6.5 CM with suppressor and its downright pleasant to shoot, and lots of folks here are happily shooting even shorter suppressed rifles.
With a good hunting suppressor, we're talking roughly ~130-140db 16-18" suppressed, vs 125-130db long suppressed, and >155db for unsuppressed 24". Add a few decibels for +Peak higher pressure ammo and a short suppressed 6.5CM is still more pleasant to shoot than a 30-06, 7prc, and larger.

Edit: for context, I also shoot 18" 30-06 suppressed, 7 prc 22" braked, and used to have a 20" 300WSM suppressed. A short 6.5cm suppressed is downright pleasant and mild in comparison to these.

 

[43.6N]

Fair point perhaps for magnums, but is muzzle blast/pressure on a short suppressed 6.5CM an actual concern, and how does overall rifle length factor into "operator experience? I run a 19" barrel 6.5 CM with suppressor and its downright pleasant to shoot, and lots of folks here are happily shooting even shorter suppressed rifles.
With a good hunting suppressor, we're talking roughly ~130-140db 16-18" suppressed, vs 125-130db long suppressed, and >155db for unsuppressed 24". Add a few decibels for +Peak higher pressure ammo and a short suppressed 6.5CM is still more pleasant to shoot than a 30-06, 7prc, and larger.

Edit: for context, I also shoot 18" 30-06 suppressed, 7 prc 22" braked, and used to have a 20" 300WSM suppressed. A short 6.5cm suppressed is downright pleasant and mild in comparison to these.

Cube root law of volumetric gas expansion:
After bullet exits muzzle, and pressurized gas is exposed to the open environment, it will expand decreasing its intensity by a ratio of distance cubed.

So longer barrel puts the point source of the shockwave further from our inner ear, allowing the shockwave to dissipate its intensity much more rapidly than someone would intuitively expect.

It’s still high pressure, and still painful. And bigger powder charges over tighter bore constrictions will give higher “uncorking pressures.”

Real life example: my 18” 6.5 creed. If I shoot without a suppressor, I get headaches and brain fog after 3 shots.
24” 6.5 creed shooting same load unsuppressed: I’m good for about 10-15 shots before feeling concussed.