The 6UM

[Quandary]

Will the Whidden 6UM die set be available in both the 30* and 40* shoulders?

 

[Kronos]

There are already people getting 3,500fps MV with 115’s and the UM.

Yes, but with less recoil and getting those speeds with a shorter barrel is a win-win for hunting. I wouldn’t want to use it for high round use target practice… I’m assuming the barrel life would be pretty short.

 

[Formidilosus]

Yes, but with less recoil and getting those speeds with a shorter barrel is a win-win for hunting. I wouldn’t want to use it for high round use target practice… I’m assuming the barrel life would be pretty short.

How would a steel alloy 6UM case decrease recoil?

 

[HuntHarder]

How would a steel alloy 6UM case decrease recoil?

Isn't the whole premise of the steel cases, to use less powder to achieve higher pressure and velocity? Less grains of powder will produce less recoil or am I totally misunderstanding the new cartridge from federal?

 

[WMelbgator]

Federal isn't going to let that case out for sometime. They spent money developing it and I'm sure they have patients on it. If they do start selling or give other companies licenses to make it, it's going to be expensive. Federal is discounting the cost of the Backcountry to gain market share.

 

[Formidilosus]

Isn't the whole premise of the steel cases, to use less powder to achieve higher pressure and velocity? Less grains of powder will produce less recoil or am I totally misunderstanding the new cartridge from federal?

That wasn’t what @Kronos asked. He asked when there would be steel alloy 6UM cases to allow 3,500fp mv with 115gr bullets. I pointed out that there are already 6UM’s doing 3,500fps MV with 115’s. To which he replied “but with less recoil”. That’s makes no sense.

A steel alloy case allows you to load to higher pressure, and therefore achieve higher MV in the same cartridge- it’s isn’t going to reduce recoil in the same cartridge, but increase it.

 

[HuntHarder]

That wasn’t what @Kronos asked. He asked when there would be steel alloy 6UM cases to allow 3,500fp mv with 115gr bullets. I pointed out that there are already 6UM’s doing 3,500fps MV with 115’s. To which he replied “but with less recoil”. That’s makes no sense.

A steel alloy case allows you to load to higher pressure, and therefore achieve higher MV in the same cartridge- it’s isn’t going to reduce recoil in the same cartridge, but increase it.

Makes sense, same case, but different metals would not change much except the ability to increase pressure. It would have to be a redesigned case to try and achieve similar ballistics with less recoil. Thus new case using less powder to get similar velocities.

 

[khuber84]

Muzzle pressure from a 20" going 3300 VS a 26" going 3500 is going to be higher. The 20" is going to be 12oz or more lighter too. I bet recoil difference is near identical between the two. What does 200fps get you? The ability to maintain terminal performance from 1000 to 1150-1200y? 99.9% of shooters have no business engaging game at either distance, myself included.
The only hybrid case around is the sig. The new 7mm backcountry isn't a hybrid, it's a steel alloy. Every steel alloy case I've found is unreloadable. If you want once and done brass, just load your virgin adg 6um brass to absolute max. It'll blow the primer likely and the case will be junk, but you got all that velocity you're looking for! Jake at unknown has said he runs that 20" 300rum in that exact fashion! One firing and the case is done, that how absurd the pressure is. I don't recommend doing any of this dumb shit, but people do it! And if you want all this speed, it's gonna be what you have to do. However, I DON'T recommend it.

 

[GoatPackr]

Case won't matter on recoil.
It takes x pressure to move a load forward at y speed.
Stronger case won't matter because it will take the same amount of work to move the load.
Yes you could use a faster powder and increase pressure and get more speed but that will also increase recoil and yes you could use a shorter barrel and get same speed with the added pressure but you also just chopped off weight so you added even more recoil.

 

[Brix8984]

Case measurements


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@Ryan Avery listening to the shoot to hunt podcast today about the 6um and I believe you stated that the 6um30 and the 6-6.5 prc had the same case capacity and one could expect 3150 fps out of a 20” barrel. Is that accurate and these numbers written on the page are wrong or am I just slow per usual and misunderstanding?

 

[Ryan Avery]

@Ryan Avery listening to the shoot to hunt podcast today about the 6um and I believe you stated that the 6um30 and the 6-6.5 prc had the same case capacity and one could expect 3150 fps out of a 20” barrel. Is that accurate and these numbers written on the page are wrong or am I just slow per usual and misunderstanding?

No, I am slow and stated it wrong. I also got more first-hand data on the 6-6.5 PRC with 115 Dtacs and 108 last week and will put up numbers and fix that part of the podcast. I have to stop drinking and podcasting.

 

[khuber84]

listening to the shoot to hunt podcast today about the 6um and I believe you stated that the 6um30 and the 6-6.5 prc had the same case capacity and one could expect 3150 fps out of a 20” barrel. Is that accurate and these numbers written on the page are wrong or am I just slow per usual and misunderstanding?

My 20in 6prc topped out at 3170 with rl26(mild pressure signs). N570 topped out at 3130, no pressure, out of capacity.

Edit, this was with 115 dtacs, 240k freebore, adg brass.

 

[Castle Rock]

A steel alloy case allows you to load to higher pressure, and therefore achieve higher MV in the same cartridge

The primer is going to be the limiting factor here
To improve much is going to take a different priming system, probably along the lines of the failed Remington electrically fired concept

 

[Formidilosus]

The primer is going to be the limiting factor here
To improve much is going to take a different priming system, probably along the lines of the failed Remington electrically fired concept

I’m not following..?

 

[Castle Rock]

Steel and composite cases will take much higher pressures.
To achieve higher velocities a new way to ignite the powder has to be developed because the primer cup is the weakest link

 

[gabenzeke]

The primer is going to be the limiting factor here
To improve much is going to take a different priming system, probably along the lines of the failed Remington electrically fired concept

Didn't the etronics or whatever rifles just use a different priming/ignition system? I feel like you could still use the same brass....so it would still have the same capacity to handle pressure I would think.

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[Formidilosus]

Steel and composite cases will take much higher pressures.
To achieve higher velocities a new way to ignite the powder has to be developed because the primer cup is the weakest link

The primer isn’t an issue. The Sig Fury is ran over 85,000 PSI with standard primers.

 

[Gstew1930]

since we are talking about this steel case ammo, i have a question i was thinking about last night. With regards to recoil, same bullet going the same speeds as a 7 PRC. The recoil should be the same correct? or does the weight & amount of propellent play a factor?

 

[DangerRanger]

I believe the amount of propellant is one of those technically yes as the recoil has to account for moving the mass of the propellant out of the barrel.

But o don’t know how that compares with a pressure increase.

My brain is saying if 2 scenarios both involve the same 150gr bullet at 3000fps (theoretical) in the same length barrel the one using 10 grains more powder simple has to recoil more. Not much, but technically more

 

[Gstew1930]

I believe the amount of propellant is one of those technically yes as the recoil has to account for moving the mass of the propellant out of the barrel.

But o don’t know how that compares with a pressure increase.

My brain is saying if 2 scenarios both involve a 150gr bullet at 3000fps (theoretical) in the same length barrel the one using 10 grains more powder simple has to recoil more. Not much, but technically more

Thats where im at with it too