What is your take on the new 7mm Backcountry?

[Wind Gypsy]

The whole thought of it tempts me to make 6 and 6.5 creedmoor cases out of hybrid 277 fury cases and load them to get 26" barrel type velocities out of my 18" suppressed tubes.

 

[Wind Gypsy]

4. The steel case can withstand 80,000 PSI (SAMMI spec is 65,000 psi). That DOES NOT MEAN that firearm actions, barrels, suppressors (especially suppressors) are designed to withstand repeated 80,000 PSI pressures. Seekins has already come out saying that they will have to redesign an action to accommodate this cartridge.

Seems like they are just chambering it in a bunch of existing actions because bolt thrust with 80k PSI on a standard bolt head isn't any more than the SAAMI 62k or 65k PSI across the larger area of magnum bolt heads. I have no idea but the whole high pressure cartridge reference by seekins on their new 3 lug actions felt like as much a marketing explanation as anything else. I dont understand why they went all weatherby with stacking their lugs on the 4 lug havak actions anyway if that isn't at least as strong as the basic typical 2 lug actions that are going to get chambered in this round.

 

[Elky Welky]

Not everyone reloads, so this seems like a nice turnkey option for folks who want to hunt suppressed. It would be foolish (and expose Federal to serious liability) to bring it to market without extensive testing to make sure actions can handle the pressure. And given the number of guns that are going to chamber it, I think they've positioned this nicely to do many of the things the 7 PRC promised--but has so far failed--to do out of the box.

I'm all for innovation, and look forward to seeing what happens with this.

 

[44hunter45]

Almost every hand loader has pushed their pressures to 80,000 psi, maybe without knowing it. If your primers are falling out, you are likely there.
Here's where I am stuck regarding this fancy new cartridge. Never mind that steel alloy casings have been around as long as boxer priming.

If you push a ladder test past what is recommended, you will experience a point where all the pressure in the world will not get you any more worthwhile velocity gain. This leads me to think this new round is inefficient to say the least.

Still, more pressure means a cleaner burn. If I were using a can and wanted reduced muzzle flash, that would be a good thing.

 

[44hunter45]

Seems like they are just chambering it in a bunch of existing actions because bolt thrust with 80k PSI on a standard bolt head isn't any more than the SAAMI 62k or 65k PSI across the larger area of magnum bolt heads. I have no idea but the whole high pressure cartridge reference by seekins on their new 3 lug actions felt like as much a marketing explanation as anything else. I dont understand why they went all weatherby with stacking their lugs on the 4 lug havak actions anyway if that isn't at least as strong as the basic typical 2 lug actions that are going to get chambered in this round.

Lots in play there. P.O. Ackley experimented with oiled cartridges and removing the lugs on bolts to understand the nuances of bolt thrust. He set out to prove that the less taper the cartridge has, the more it grips the chamber walls. He succeeded.

 

[mtmuley]

The whole thought of it tempts me to make 6 and 6.5 creedmoor cases out of hybrid 277 fury cases and load them to get 26" barrel type velocities out of my 18" suppressed tubes.

Keep us posted. mtmuley

 

[sclancy27]

Seems like they are just chambering it in a bunch of existing actions because bolt thrust with 80k PSI on a standard bolt head isn't any more than the SAAMI 62k or 65k PSI across the larger area of magnum bolt heads. I have no idea but the whole high pressure cartridge reference by seekins on their new 3 lug actions felt like as much a marketing explanation as anything else. I dont understand why they went all weatherby with stacking their lugs on the 4 lug havak actions anyway if that isn't at least as strong as the basic typical 2 lug actions that are going to get chambered in this round.

Each action must have a design pressure based on a governing body (SAMMI I assume?). That design pressure has a safety factor the same as pipe does for pressure. That safety factor is controlled by the governing body.

Say, for example, the safety factor is regulated at a minimum of 2. So, in order to be rated at 65000 psi, the action must be tested to 130,000 PSI, minimum. On any firearm with a safety factor under 2.46 (2x80K= 160k. 160K/65K= 2.46) they would not be able to use the action with an 80,000 PSI cartridge.

***I have no idea what the safety factor for rifle actions are or what an actions burst pressure may be***

 

[jimh406]

I heard/read that actions are tested to 110-120k psi. The issue is the cases can't handle it which is the reason for the stronger case.

 

[D4570]

What could possibly go wrong with another 20ksi. And it's not reloadable.

I have read they are reloadable

 

[44hunter45]

The whole thought of it tempts me to make 6 and 6.5 creedmoor cases out of hybrid 277 fury cases and load them to get 26" barrel type velocities out of my 18" suppressed tubes.

Reloadable does not mean it is practical to do so.

If you have ever played with resizing steel cases or converting cartridges you know you get short die life.
You will get radial cracks around the base of the die.

Back when I got my 1896 Mauser in 6.5 Swede there was no brass to be had anywhere. I converted 200 rounds of military 30-06. First you cut it shorter, then anneal it, and then run it through your die, then ream and trim. The .473 rim is a little too small, but they worked.

This is what 200 rounds did to my 6.5x55 sizing die. Imagine trying this with "special steel alloy".

I'm betting their alloy is about identical to a Wolf steel case. Wolf is a US company who "sources their ammo from several European Companies".

Federal is now officially owned by CSG in Czechoslovakia. Why shouldn't they produce steel cased voodoo. They are supplying steel ammo all around the world, why not try to convince US shooters it is the coolest new thing?

 

[jimh406]

Reloadable does not mean it is practical to do so.

You are just guessing until cases and reloading equipment are available. You may or may not be right.

 

[Ought Six]

Meh

 

[mtmuley]

Meh

Yep. mtmuley

 

[44hunter45]

You are just guessing until cases and reloading equipment are available. You may or may not be right.

Doesn't matter to me. I ain't buying one.

 

[grizzly_]

I'll stick with 300WM and 7mm Rem Mag.

And if my gun makes it to Botswana or Yellowknife or some other BFE place and my ammo gets lost on the flight, odds are much better I can buy a box off a local and still go hunt.

 

[elkhuntinfool78]

They come out with a new cartridge every other day it seems anymore. At the end of the day if it gets you excited then go for it. On the the flip side there are countless others that would work also. My biggest gripe if I were to buy a new cartridge would be how do you choose which ones will be here for the long term? No doubt many will be forgotten in the near future. I myself won't be biting on the 7 bc but that doesn't mean it's not a great cartridge for you.