Do you happen to know the velocity? And bullet weight?
Thanks.
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Thoughts on New Federal 7mm Back Country
- Thread starter lacajun
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It's a 195 elite hunter running at 2965 plus or minus depending on the temp
Thanks.
pavementends
Well-Known Member
- Joined
- Nov 30, 2017
- Messages
- 126
Is it hype? Some of course however many are showing chrono results with the shorter barrels. Savage is showing multiple offerings. How long will the actions last? Who knows at this point. Recoil most agree is dependent on bullet weight and the weight of the propellent. Barrel life, I am not aware of a definitive test comparing pressure vs unburned powder to see which has the most effect. On the other hand maybe federal just wants to sell stuff, the barrel makers lack sales and want barrels to wear out quicker, gun makers want actions to fail so we buy more and Garmin is in on it with fake velocity numbers to make us think the 7BC is fast out of short barrels.
Bottom line, its new and to some is a direct challenge to their favorite.
i.e. Its new, we don't need it, I hate it and why don't the spend their time making 32-40 or whatever my passion is.
Buy or don't buy.
Bottom line, its new and to some is a direct challenge to their favorite.
i.e. Its new, we don't need it, I hate it and why don't the spend their time making 32-40 or whatever my passion is.
Buy or don't buy.
Gun makers may want barrels to wear out, but they don't want actions to fail. If a rifle manufacturer offers the chambering, you can be sure that the action will handle it just fine. Well, at least in a bolt action. A semi-auto would be another story.
Josh06
Well-Known Member
I think it looks interesting. I have a lightweight 20" 280ai and would love to switch that barrel out to a 16" 7mm backcountry and get better performance in a lighter/smaller package. I'll be waiting until we hear about reloading and see some real world reviews but I think it looks promising.
Looking at a recoil calculator pressure isn't listed as a variable. Only muzzle velocity, rifle mass, and mass of the powder and projectile. That would suggest this has a recoil advantage compared to burning more powder to achieve the same velocity at a lower pressure.
Using 60gr of powder (about what will fit in a 7BC) to drive a 175gr bullet at 3000fps in a 7lb rifle generates 30ft*lbs of recoil energy. Using 80gr to do the same thing(about how much powder another member mentioned in his 28Nosler) generates 38ft*lbs of recoil energy. A 25% increases in recoil. Based on that members results, the 175gr bullet would likely be going a little faster from a 28Nosler, but that would increase the recoil further. So from a recoils standpoint, the 7BC seems advantageous.
Using 60gr of powder (about what will fit in a 7BC) to drive a 175gr bullet at 3000fps in a 7lb rifle generates 30ft*lbs of recoil energy. Using 80gr to do the same thing(about how much powder another member mentioned in his 28Nosler) generates 38ft*lbs of recoil energy. A 25% increases in recoil. Based on that members results, the 175gr bullet would likely be going a little faster from a 28Nosler, but that would increase the recoil further. So from a recoils standpoint, the 7BC seems advantageous.
Another potential advantage has just popped into my mind. Sound. Sound is a pressure wave. Higher MUZZLE pressure means a louder bang.
If we compare a 28Nosler to 7BC with the same barrel length, and load the 28Nosler case until we have the same muzzle velocity from both the 28Nosler, and the 7BC, the 7BC will be less loud. The reason is because for both bullets to be going the same velocity from the same length barrel, the AVERAGE pressure from chamber to muzzle will have been equal. If the average pressure is equal, but the 7BC has a higher chamber pressure, then it will have a lower pressure at the muzzle. While this might be less important in a suppressed application, the 7BC should be easier to suppress than a 28Nosler.
That may seem strange, but when we go from a 7-08 to a 280ai, or a 280ai to a 28Nosler to increase velocity, we start with roughly the same chamber pressure, and we increase velocity by burning more powder to achieve a higher MUZZLE pressure.
Obviously the 7BC would be louder than a smaller cartridge pushing the same bullet slower from the same length barrel. It isn't magic. But in terms of comparing it to a larger 7mm that might approximate it's performance, the 7BC should produce less recoil, and be easier on the ears.
If we compare a 28Nosler to 7BC with the same barrel length, and load the 28Nosler case until we have the same muzzle velocity from both the 28Nosler, and the 7BC, the 7BC will be less loud. The reason is because for both bullets to be going the same velocity from the same length barrel, the AVERAGE pressure from chamber to muzzle will have been equal. If the average pressure is equal, but the 7BC has a higher chamber pressure, then it will have a lower pressure at the muzzle. While this might be less important in a suppressed application, the 7BC should be easier to suppress than a 28Nosler.
That may seem strange, but when we go from a 7-08 to a 280ai, or a 280ai to a 28Nosler to increase velocity, we start with roughly the same chamber pressure, and we increase velocity by burning more powder to achieve a higher MUZZLE pressure.
Obviously the 7BC would be louder than a smaller cartridge pushing the same bullet slower from the same length barrel. It isn't magic. But in terms of comparing it to a larger 7mm that might approximate it's performance, the 7BC should produce less recoil, and be easier on the ears.
^^^How significant the difference in sound between a 7BC and 28Nosler with the same barrel lengths would be, I really don't know. Pressure as the bullet moves down the barrel isn't linear, and will have dropped substantially by the time the bullet reaches the muzzle in both cartridges. Muzzle pressure is probably dependent primarily on barrel volume and how much powder was used. Based on that I would guess a 7BC to be equally loud compared to a 280ai, while outperforming it.
adam32+P
Well-Known Member
Actions will be fine...it's just now Federal is being honest that they are running 80k...Sherman's have been running that since they came out, just no published data on them.
Buzzsaw
Well-Known Member
why would anyone trash ANYTHING which might be good for our sport? Human nature to just be negative about anything they don't have?
so you just bought a 7mmPRC or you have your wonderful .280AI. good for you but no need to be negative about any new stuff for us.
so you just bought a 7mmPRC or you have your wonderful .280AI. good for you but no need to be negative about any new stuff for us.
SteveBurton
Formerly 'Jackmonkey'
The 7mm Backcountry is NOT as Good as They're Saying?
Podcast from Unknown Munitions goes over a lot.
Me personally, I think it will flop.
Podcast from Unknown Munitions goes over a lot.
Me personally, I think it will flop.
