Federal New Cartridge

[cmahoney]

Ok, I just got slightly more intrigued by these new fangled cases. I’m pretty sure I have a slow twist 243 tikka barrel I pulled off a donor. I also have some 55gr Hammers I use for a very low recoil 243 round. Quick math in my head says 4k plus, for the cost of a few of these cases and some time at the bench. Hmmmm


Sent from my iPhone using Tapatalk

I get 4000 FPS with 55 grain ballistic tips out of a 24” .243 with 8208 in brass cases.


Sent from my iPhone using Tapatalk

 

[roadrunner]

Him and Spomer have already made a video touching tips and raving about the authority this cartridge brings to the table.

*Spomer and he. You use "he" to replace the subject name Joe VonBenidict.

Yeah, I'll go all holier than thou and church it up a little

 

[Flyjunky]

Hornady the other day said on their podcast, they see more correlation with throat erosion to powder volume vs bore size and little to do with pressure. Comparing some 50k cartridges vs 63k.

S2H said on their podcast, rcbs is stalled in building reloading components for it, it taking as much as 12 passes through a die to resize. If that's the case, this is DOA for anyone but the factory gun, factory ammo guy. And at $4+ per round, it's unlikely anyone will be shooting this enough to be proficient at the long ranges the cartridge is meant for.

I agree, the success of this cartridge, long term, will be tied to the ability to reload these cases.

 

[z987k]

I get 4000 FPS with 55 grain ballistic tips out of a 24” .243 with 8208 in brass cases.


Sent from my iPhone using Tapatalk

Get 2ish firings from that? You're likely north of 70kpsi.

 

[solarshooter]

Recoil comparison for a 7PRC and 7BC at the same speed, with my best estimates of powder charge and accounting for higher muzzle exit pressure/powder velocity increase due to higher chamber pressure (e rif is the column for recoil energy):

Tiny difference in recoil. We could debate on muzzle exit pressure/powder velocity increase at bullet exit, or better yet maybe someone could run some Quickload/GRT iterations and post those pressure curves for assessment. But from this I don't see a benefit other than maybe the 7PRC cannot actually hit 3k in 20". Running a 28 Nos which I think can do that no problem:

So in that case there is a more noticeable difference. However I'm now a little skeptical the 7BC can even hit 3k in 20" at 80ksi... again need some Quickload investigations to see if that actually works.

Fundamentally though I don't see the benefit of higher mv with the 175 class 7mm - it's still an 8mph gun and terminal ranges are still STUPID far. It's just more recoil.

 

[solarshooter]

Some more thoughts on barrel life. Higher pressure means higher temperature. My understanding from discussions on double base powders is that higher temps mean faster barrel erosion. Therefore I would not be surprised if barrel life is more consistent with the larger powder charges. Despite what marketers want you to think, you can't fool physics and there are no free lunches!

I would say at this point the only potential benefit I can identify is shorter barrel length, but even that is a little suspect to me.

 

[Article 4]

Looks like Weatherby is up with their announcement in the 307 and the Mark 5

 

[doc holiday13]

It’s getting blasted because it’s only adding to a performance stat (velocity over 3k) that shooters care less about every day as other tech increases.
What happens when another company comes out with steel case ammo for a 7rem, 7-08, or PRC in a couple months? The backcountry will be irrelevant, for those who cared in the first place, before the ‘25 hunting season even starts.

Exactly. the cartridges will be harder to make in steel so no smaller outfits will wanna make it in steel so they'll make a brass version.

 

[solarshooter]

OK I did some more digging, looks like people are getting about 2900fps with handloaded 7PRC and 175/180s. Backfire's video showed 2880 from a 16" barrel with a 175, so adjusting up to 20" using 25fps/in we do get about the advertised 3000fps. So with those numbers:

Slightly more MV for slightly more recoil. And the same wind number.

 

[BelowAverageBowhunter]

I'd really like to see a bore scope after 700rds I'm thinking the barrel life on this one is going to be right in line with all the other overbore stuff doing these speeds even with the reduced charge. I've seen more fire/pressure cracking problems than throat erosion on my barrel burners and I'm guessing the 17k psi increase isn't going to help.

 

[gbflyer]

I got the notify me when available email from Powder Valley. Looks like $50-$65 per box for ammo.

 

[littlebigtine]

OK I did some more digging, looks like people are getting about 2900fps with handloaded 7PRC and 175/180s. Backfire's video showed 2880 from a 16" barrel with a 175, so adjusting up to 20" using 25fps/in we do get about the advertised 3000fps. So with those numbers:
View attachment 819382
Slightly more MV for slightly more recoil. And the same wind number.

Can you explain to me the relatioship between powder,velocity, pressure and recoil. Intuitively to me, it makes no sense that influencers are claiming that this has less recoil than the 7prc with higher velocities out of the same size barrel… so how does the increase in pressure correlate with free recoil?

 

[Bluefish]

Can you explain to me the relatioship between powder,velocity, pressure and recoil. Intuitively to me, it makes no sense that influencers are claiming that this has less recoil than the 7prc with higher velocities out of the same size barrel… so how does the increase in pressure correlate with free recoil?

Pressure has no direct bearing on recoil. Recoil is effectively momentum, mass x velocity of the gun has to equal mass x velocity of the ejected material. Ejected material is powder and bullet. More pressure means more velocity of the bullet for the same amount of the same powder. By using less powder to get the same velocity due to higher pressure the recoil is less. You can also do the same thing by changing powders. If a powder gets more velocity for a smaller charge it has slightly less recoil. It becomes a pretty small difference, but marketing takes anything they can get.

There was a guy who researched the pressure vs recoil pretty extensively for shot shells. Neil was his first name. Now deceased but he did some pretty scientific research on the subject. The only measurable difference was the recoil starts ever so slightly sooner with higher pressure. If I remember right, it was on the order of 1 millisecond or less. Too fast for the body to perceive any difference.

 

[BelowAverageBowhunter]

Can you explain to me the relatioship between powder,velocity, pressure and recoil. Intuitively to me, it makes no sense that influencers are claiming that this has less recoil than the 7prc with higher velocities out of the same size barrel… so how does the increase in pressure correlate with free recoil?

Not who you were asking but everything that comes out of the end of the barrel contributes to recoil(bullet and burnt/unburnt powder). so if you have a 175gr bullet at 2800fps and 70 grains of powder(70 grains of powder turns in to 70 grains of gas once its burnt) in the case of the prc. That's 245gr of material exiting the barrel. With the 7 BC if it only takes 55 gr of powder you have 10 grains less leaving the barrel it's like shooting a lighter bullet when it comes to recoil.

This is all overly simplified and the gasses leaving the barrel are traveling faster than the bullet in both cases so if the pressure at muzzle exit is higher(gasses traveling faster after muzzle exit) it could likely cancel eachother out. Higher gas speeds could make a muzzlebrake or suppressor very effective though.

 

[solarshooter]

Can you explain to me the relatioship between powder,velocity, pressure and recoil. Intuitively to me, it makes no sense that influencers are claiming that this has less recoil than the 7prc with higher velocities out of the same size barrel… so how does the increase in pressure correlate with free recoil?

Calculating recoil energy involves first doing a conservation of momentum calculation of the bullet/powder and rifle to find the rifles velocity, and then using that and the rifles mass to calculate the energy of the rifle.

Conservation of momentum to solve for rifle velocity:
(mass_bullet * velocity_bullet + mass_powder * velocity_powder)/mass_rifle = velocity_rifle

Solve for rifle energy/recoil energy:
1/2 * mass_rifle * velocity_rifle^2 = energy_rifle, aka recoil energy

The mass and velocity of the powder can be a significant part of the total momentum, partly because it's a decent chunk of mass, but also because the powder travels at a high velocity out of the barrel - faster than the bullet. If you watch slow-mo videos of bullets leaving the muzzle, you will see the cloud of burnt powder gas momentarily overtakes the bullet until it diffuses and slows down and the bullet exits the cloud.

I've done some searching and the general consensus is the powder is leaving the barrel around 5000fps for typical rifles and barrel lengths. This speed will depend on muzzle exit pressure, and this is where it gets a little hard to know how the 7BC recoil will pan out. For the numbers above, I've assumed there will be an ~20% increase in muzzle exit pressure and thus powder exit velocity, proportional to the increase in chamber pressure, so 6000fps.

If I instead run it with 5000fps, you get the "free performance" everyone is talking about.

 

[solarshooter]

To really calculate this stuff might be a little involved, but we could at least get a sense for it with some Quickload/GRT runs to see what the relative muzzle exit pressure might be.

Yes higher pressure gas could produce more braking effect from a brake/suppressor. It will also be louder.

There are some interesting second order things to consider with higher exit pressures. Some people are of the opinion that higher MEP is less accurate, because those gasses are going faster relative to the bullet and can push on it in an asymmetric way. This is why flat base bullets are considered more accurate for short range BR, there is no boat tail surface for this "reverse airflow" to push sideways on. This is also why some think that muzzle devices like brakes and suppressors can aid accuracy because they strip these gasses away from the bullet and reduce this effect.

There is also the question of recoil impulse. I know the hot thing in PRS right now is running essentially a 6BR charge in a 6 Dasher case. MVs are very similar to 6BR, but the shooters claim the recoil impulse is "softer" and "slower" which aids in accuracy when shooting from weaker positions, and aids in spotting impacts. I'm sure this scenario corresponds to less peak pressure, and I wonder if the inverse effect will be true with this high pressure cartridge. Will it feel extra "sharp" and "explosive"?

 

[Sundodger]

To really calculate this stuff might be a little involved, but we could at least get a sense for it with some Quickload/GRT runs to see what the relative muzzle exit pressure might be.

Yes higher pressure gas could produce more braking effect from a brake/suppressor. It will also be louder.

There are some interesting second order things to consider with higher exit pressures. Some people are of the opinion that higher MEP is less accurate, because those gasses are going faster relative to the bullet and can push on it in an asymmetric way. This is why flat base bullets are considered more accurate for short range BR, there is no boat tail surface for this "reverse airflow" to push sideways on. This is also why some think that muzzle devices like brakes and suppressors can aid accuracy because they strip these gasses away from the bullet and reduce this effect.

There is also the question of recoil impulse. I know the hot thing in PRS right now is running essentially a 6BR charge in a 6 Dasher case. MVs are very similar to 6BR, but the shooters claim the recoil impulse is "softer" and "slower" which aids in accuracy when shooting from weaker positions, and aids in spotting impacts. I'm sure this scenario corresponds to less peak pressure, and I wonder if the inverse effect will be true with this high pressure cartridge. Will it feel extra "sharp" and "explosive"?

Great thoughts.

Something I have been pondering, in my field (which is not firearms) higher internal combustion temperatures and pressures result in lower unburned hydrocarbon particulates at the cost of nitrogen oxide formation.

No one cares about nitrogen oxide emissions in guns, but I have talked to gun enthusiasts that claim unburned powder hitting the back of the projectile as it leave the barrel impact accuracy.

I wonder if these higher pressures can minimize this accuracy loss. Another thing to note is I have no idea how much this impacts accuracy if at all, for all I know it might be negligible compared to other factors.

 

[ACHILLES]

More psi is more recoil right? Why is this changing the game? Its not like your having your cake and eating it 2… some one carr to clear this up for me? A 6.5 creed running that 80k psi approaches 6,5 prc capability? But the recoil would also be trending that direction?

I’m all for advancements and see the benefits for certain applications and I’m sure will try it out myself at some point. But here’s how I view it now for hunting.
I can either buy a 7prc rifle, brass, dies or factory ammo for $50/box. Or I can buy a 7BC rifle which I’m guessing is going to be more expensive, more expensive dies, and alloy cases, or factory ammo for Im guessing $80-$100 box or more.
Both will probably achieve similar performance(guessing within 100fps) and I’m assuming close to the same recoil. It’s just going to cost way more to shoot the 7BC.
Also I would think this will change the minimum barrel length ratings for your suppressor. I would also assume a 7BC country is going to be pretty loud at 80kpsi out of a 16” Bbl no matter what can your using.

 

[dirtshooter]

7mm flatbrim

 

[Sundodger]

I’m all for advancements and see the benefits for certain applications and I’m sure will try it out myself at some point. But here’s how I view it now for hunting.
I can either buy a 7prc rifle, brass, dies or factory ammo for $50/box. Or I can buy a 7BC rifle which I’m guessing is going to be more expensive, more expensive dies, and alloy cases, or factory ammo for Im guessing $80-$100 box or more.
Both will probably achieve similar performance(guessing within 100fps) and I’m assuming close to the same recoil. It’s just going to cost way more to shoot the 7BC.

Good chance you are right, I am very curious to how all this pans out. Only time will tell, and maybe Gen1 of this stuff is just that, but maybe in another 10 years Gen4 of this stuff will really make the juice worth the squeeze.

Also I would think this will change the minimum barrel length ratings for your suppressor. I would also assume a 7BC country is going to be pretty loud at 80kpsi out of a 16” Bbl no matter what can your using.

I am VERY curious what the pressure curve (with respect to time or barrel length) looks like on this cartridge. Maybe the pressure crashes pretty quickly and it's actually quieter. Seems unlikely, but does anyone know what they are unique powder? Something unique possibly?