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Shooting & Reloading - Mausers, Big Bores and others >> Rifles

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85lc
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A new type cartridge - 7mm Backcountry
      #388779 - 11/01/25 06:07 AM

https://www.americanhunter.org/content/an-in-depth-look-at-7mm-backcountry/?

An In-Depth Look at 7mm Backcountry
by NRA Staff posted on January 7, 2025
Videos News Ammo Videos Review New For 2025

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Federal Ammunition set out to create a brand-new 7mm, with an eye toward speed, suppressors and seriously heavy bullets. This pursuit, which has culminated in the 7mm Backcountry, can be encapsulated by three measurements: 20, 170 and 3,000. What does this mean? Through 20-inch barrels and with 170-grain bullets, the 7mm Backcountry—not a magnum cartridge—can achieve 3,000 feet-per-second (fps). How it does it is the real question. For the answer, read on, or check out the video embedded above.

The first and most important part of the answer is the cartridge's unique, Peak Alloy case. The patented, high-strength steel alloy—similar to the steel alloys used in bank safes, race cars, and nuclear reactors—is stronger than brass used in conventional cases. This allows it to safely handle higher chamber pressures, boosting velocities to magnum levels through a shorter barrel while maintaining comparable, if not reduced, perceived recoil.

7mm Backcountry Expansions

This leads to some incredible results. Federal’s 155-grain Terminal Ascent bullet, the lightest bullet Federal will initially offer in 7mm Backcountry, has an astonishing 24-inch barrel muzzle velocity of 3,300 fps. And, its 20-inch barrel data comes in at 3,150 fps. Through a 16.5-inch barrel, it can still clock an impressive 3,000 fps. Federal’s load, with the heaviest bullet being offered and with the highest ballistic coefficient (the Berger Elite Hunter 195-grain bullet), produces a 24-inch barrel muzzle velocity of 3,000 fps. Its 20-inch barrel velocity still comes in at 2,850 fps. These remarkable numbers are currently unreachable, even in 7mm PRC.

“7mm Backcountry is a result of six years of development,” explained Abramowski. “Driven by the U.S. military’s need for improved performance ammunition, we tested many materials at high pressures to ensure rifle function out of a one-piece case configuration for manufacturing efficiency and design reliability. Peak Alloy delivers everything we dreamed it would. It can be loaded at a maximum chamber pressure of 80,000 pounds per square inch (psi) and achieve 3,000 fps velocities with 170-grain class bullets out of 20-inch barrels.”

When developing the cartridge, Federal engineers developed testing to confirm safety when loading high-strength steel cases at 80,000 psi.

Case on box

So why design something with an eye toward shorter barrel performance? In a word, suppressors. Hunting suppressed has become all the rage lately, and its not hard to see why. With less felt recoil and hearing-safe options, shooting suppressed saves ears and shoulders alike.

“We acknowledge that hunters are moving away from magnum cartridges in long barrels to short, light, compact rifles with suppressors,” said Mike Holm, Federal’s director of centerfire rifle ammunition. “However, cartridges and rifles haven’t kept pace with this trend. Installing an 8-inch suppressor on a 24-inch barrel results in an awkward and impractical platform."

7mm Backcountry Cartridges

Initial Offerings

Federal launched its new cartridge with a gamut of all-range and long-range projectiles to best exploit the velocity, energy, range and trajectory advantages of 7mm Backcountry. These flat-shooting, 170-plus-grain class, heavy-for-caliber bullets offer a balance between sleekness and energy, touting high ballistic coefficients (BC).

“Our goal was to take the new case technology and design the ultimate, high-tech hunting cartridge that could handle loadings at a higher pressure,” said Eric Miller, Federal's centerfire rifle product line manager. “We also wanted it to operate in non-magnum, standard long actions to keep room for round capacity. The result is a non-magnum-looking cartridge with the same neck length as 7mm PRC, body taper and shoulder angle as 6.5 Creedmoor, and a cartridge size similar to 30-06 Springfield or 280 Ackley Improved. Yet it accepts heavy bullets with a long ogive.”

“Terminal Ascent is our flagship all-range big game bullet that extracts the utmost performance from the 7mm Backcountry cartridge,” continued Miller. “Its bonded construction penetrates deep on close targets, while the patented Slipstream polymer tip initiates expansion at extreme long range. The 155-grain load is the fastest 7mm on the market with 3,150 fps out of a 20-inch barrel, while the 170-grain achieves 3,000 fps out of 20-inch barrels. The 155-grain bullet has a G1 BC of .586, and the 170-grain is .645.”

Next is Federal’s Barnes LRX 168-grain load. This offering is specifically for those looking for an all-copper option, and achieves 3000 fps from a 20-inch barrel with a G1 BC of .513.

The Federal-engineered Fusion Tipped 175-grain provides a more traditional option, traveling at 2,975 fps from a 20-inch barrel with a G1 BC of .575

Finally, Federal will load its new 7mm Backcountry cartridge with Berger Elite Hunter 195-grain bullets. These bullets have an incredible .755 ballistic coefficient, the highest on the market among hunting bullets, and travel a blistering 2,850 fps out of a 20-inch barrel.

--------------------
RB


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85lc
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Reged: 19/01/18
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Re: A new type cartridge - 7mm Backcountry [Re: 85lc]
      #388780 - 11/01/25 06:15 AM

This is an interesting concept of revising the cartridge case to allow very high chamber pressure to acheive high velocity from a short barrel. This combination allows a can to be added and still have a reasonable total barrel length.

They are reporting velocities froma 20" barrel that are similar to what I get with a 24" barrel from my 7PRC.

The writeup indicates that there isn't undue stress on the rifle but it would seem that there would be increased barrel wear unless the powder burns cooler than traditional powders.

Interesting (to me) development.

--------------------
RB


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93x64mm
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Re: A new type cartridge - 7mm Backcountry [Re: 85lc]
      #388782 - 11/01/25 06:47 AM

80KPSI - boy that's proofing load territory!
Bit hot for me that cartridge!


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Hunter4752001
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Reged: 25/01/10
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Re: A new type cartridge - 7mm Backcountry [Re: 93x64mm]
      #388784 - 11/01/25 08:51 AM

Sounds like another dose of 6.8x51 Koolaid. Forget afordable and reloadable ammo.

Forget "cooler burning powders'. Basic law of physics - pressure varies directly with temperature. High pressure means high temperature.

The pressure also has implications for cans. Suppresors essentially work by reducing the high pressure barrel gasses down to a lower pressure exit gas. While internal design affects efficiency, the primary mechanism is volume. This means any cans on a high presure system need to larger than on a low pressure system.


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Marrakai
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Re: A new type cartridge - 7mm Backcountry [Re: Hunter4752001]
      #388789 - 11/01/25 12:10 PM

Yeah... Nah...

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au


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DarylS
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Re: A new type cartridge - 7mm Backcountry [Re: Marrakai]
      #388817 - 12/01/25 07:06 AM

Not for me, either. Too high pressure, too high vel. and a Berger-Bomb for a bullet.
I'll stick with my 1936 m70 in .30 GVT 06.
165's at 2,960fps and 180's at 2,745fps. Both shooting under 3/4" @ 100 meters.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V


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NitroXAdministrator
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Re: A new type cartridge - 7mm Backcountry [Re: Hunter4752001]
      #388825 - 12/01/25 06:29 PM

Quote:

Sounds like another dose of 6.8x51 Koolaid. Forget afordable and reloadable ammo.

Forget "cooler burning powders'. Basic law of physics - pressure varies directly with temperature. High pressure means high temperature.

The pressure also has implications for cans. Suppresors essentially work by reducing the high pressure barrel gasses down to a lower pressure exit gas. While internal design affects efficiency, the primary mechanism is volume. This means any cans on a high presure system need to larger than on a low pressure system.




I'm not understanding how a sound suppressor reduces recoil? A muzzle break, yes,but that would be very loud. Am I wrong?

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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NitroXAdministrator
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Re: A new type cartridge - 7mm Backcountry [Re: Marrakai]
      #388826 - 12/01/25 06:31 PM

Quote:

Yeah... Nah...




Yeah .... Nah x2

I'm keen on the new wonderful effective 7x57.

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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3DogMike
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Re: A new type cartridge - 7mm Backcountry [Re: NitroX]
      #388832 - 13/01/25 05:41 AM

Yeah….nah x3

I wonder what the priming system is? I rather doubt typical primers would withstand 80,000 PSI.
Doubtful that proprietary reloading components will be available, similar to the situation with the #216 primer that Federal uses in their factory .470 ammunition.
Quién sabe?
- Mike

--------------------
"Will Rogers never met a fighter pilot"
- Anon

“Always carry a flask of whiskey in case of snakebite, and furthermore always carry a small snake."
-- W. C. Fields


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DarylS
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Re: A new type cartridge - 7mm Backcountry [Re: NitroX]
      #388840 - 13/01/25 06:21 AM

Quote:

Quote:

Sounds like another dose of 6.8x51 Koolaid. Forget afordable and reloadable ammo.

Forget "cooler burning powders'. Basic law of physics - pressure varies directly with temperature. High pressure means high temperature.

The pressure also has implications for cans. Suppresors essentially work by reducing the high pressure barrel gasses down to a lower pressure exit gas. While internal design affects efficiency, the primary mechanism is volume. This means any cans on a high presure system need to larger than on a low pressure system.




I'm not understanding how a sound suppressor reduces recoil? A muzzle break, yes,but that would be very loud. Am I wrong?




The suppressor reduces recoil from the blast effect similarly to a break. A muzzlebreak spreads that blast out & is very loud as some of that blast is directed backwards towards the shooter, or straight out the sides and top, while the suppressor diffuses the blast inside it's body.
The suppressor or break are most effective when used in very high capacity cases burning a LOT of powder and producing a LOT of muzzle blast which increases recoil.
This is how I understand the phenomenon.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V


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85lc
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Re: A new type cartridge - 7mm Backcountry [Re: DarylS]
      #388850 - 13/01/25 09:04 AM

A suppressor is very similar to the muffler on your car in that it reduces the muzzle blast. It retains the muzzle gas and allows the gas out more slowly.

There are powders that burn more cooly - not cold but cooler than other powders and that reduces barrel erosion. Heat is the major contributor to barrel erosion.

This new case is just an evolution in cartridge development. At one time, cartridges developed 40,000 psi and with new powders, that limit was raised to 50,000 ps. Then newer cartridges started operating at 60,000 and then 65,000 psi. The limit was the cartridge case and not the rifle.

What Federal is saying is that this new cartridge can operate in rifles available today and not need a special rifle. That is in line with what I have read - usable chamber pressure is limited to the strength of the cartridge case.

Now, the real question is whether this cartridge will be economically viable. Are there enough buyers that want a suppressor on a rifle and have their rifle have a reasonable barrel length. It seems that a number of European hunters use rifles with suppressors. In the US, suppressors are only now becoming available; however, I don't know anyone that has a suppressor on a hunting rifle.

I don't have a suppressor and being somewhat deaf (my wife says very deaf), I don't hear a rifle or shotgun blast when hunting and wear ear muffs only while at the range. Also, while I have a few new guns, I like shooting vintage guns. That said, I am not a canidate for this rifle cartridge. However, I wouldn't be surprised that in 5 - 10 years, more new cartridges use this new case and operate at higher pressures.

That is my 2 cents.

--------------------
RB


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DarylS
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Re: A new type cartridge - 7mm Backcountry [Re: 85lc]
      #388854 - 13/01/25 12:30 PM

Suspect what you say about the future ctg. design is true, 85lc.
Steel bases allow higher pressures. As to the primer, that in itself is very important.
The mil. spec. 5.7x47? ctg. primers have harder cups to prevent slam firing in full auto rifles.
Seems to me, the mil. round generates around 57,000psi.
The .220 Swift of 1923?, generated some 62,000psi while the .22-250 Remington of 1965 was generating 65,000psi.
That's 60 years ago, now. 'Bout time something was developed producing more pressure. Just kidding. How much is needed?
Depends on who is buying, I guess.
The 8 MM Rem mag. also produced a suggested maximum pressure of 65,000psi in the States, but is listed as 67,000psi Pezio pressure in Europe.
The .300 Lap Mag. is listed highest of the current rounds at 68,000PSI - CIP.
We know that standard magnum primers used today, handle these pressures just fine - BUT - will they handle even higher pressures? 80,000psi? yikes - maybe?

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V


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Rule303
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Re: A new type cartridge - 7mm Backcountry [Re: 85lc]
      #388859 - 13/01/25 01:47 PM

A lot of Kiwis use suppressors. They do deteriorate/wear out with usage. This leads to the questions of how many rounds before needing to replace the suppressor and how big does it have to be?

what are the ballistics out of a 22" or 24" barrel as most will be hunting non suppressor. Next, will the steel case's be reloadable and if so will they require Tungsten dies or similar and will the required powders be available in gun shops?

The current cartridge may use a cooler burning powder but friction also generates heat and the faster the bullet if traveling the more surface friction heat it will generate. The barrels certainly wont last as long unless chrome lined.

So in theory I could get my 358 RUM up top near the 4000fps area with 225 grain projectiles. So using a Woodleigh Hydro I could shoot through 2 Buff, not a scenario I would want.

Think I will be a Yeah-Nah 4


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NitroXAdministrator
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Re: A new type cartridge - 7mm Backcountry [Re: Rule303]
      #388871 - 14/01/25 12:51 AM

Yes I too think if it's successful, we'll see a new range of cartridges and rifles. Progress.

But I doubt there'll be any handloading. Pay hefty $$$ every pop.

The main use will be military sniper rifles.

And idiotic 'long range 'hunting' sniper rifles'. The Crymore brigade will become the Backdoorcountry mob.

I'll stick to my desired 1890s cartridge 7x57 however. If it could kill elephant's, maneater tigers and leopards, deer galore, it still works.

And in a nice classic Mauser rifle not some wanker 2030 rifle.

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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3DogMike
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Re: A new type cartridge - 7mm Backcountry [Re: NitroX]
      #388882 - 14/01/25 01:23 PM

Well said John

“…and in a nice classic Mauser rifle not some wanker 2030 rifle…”

Emphasis on “wanker rifle” (yes, I know the term, I lived in the UK for 3 years whilst in the US Air Force)
-Mike

--------------------
"Will Rogers never met a fighter pilot"
- Anon

“Always carry a flask of whiskey in case of snakebite, and furthermore always carry a small snake."
-- W. C. Fields


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NitroXAdministrator
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Re: A new type cartridge - 7mm Backcountry [Re: 3DogMike]
      #388885 - 14/01/25 08:17 PM

Half a joke. It may be the future. Well see.

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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