Anyone tried 6.8X51/.277 Fury hybrid cases?

[Bodhisafa]

What if pressures are kept low around 62,000 psi, would these cases still cause issues?

 

[DaveTooley]

Just my opinion.
The steel section extends past the solid part of the case head. It gets thinner as it gets to the transition with the brass body. I think, even at normal pressures, that area will eventually expand just like an all brass case. Of course we're going to try and make it work in our world but it was designed to be one and done.

 

[Bodhisafa]

I am building an AR 10 for hog hunting. I was going to use this cartridge but if the brass is an issue I will need to change tracks.

What cartridge would be equivalent that would be great in an AR 10? Besides 308/6.5 creed.

 

[DaveTooley]

I am building an AR 10 for hog hunting. I was going to use this cartridge but if the brass is an issue I will need to change tracks.

What cartridge would be equivalent that would be great in an AR 10? Besides 308/6.5 creed.

If you want knock down power go 338 Federal.

 

[SKWERLZ]

I’m curious what they are doing for extractor materials and heat treatment with these steel base cases.
It’s gotta be rough on extractors designed around conventional cases.

 

[DaveTooley]

I’m curious what they are doing for extractor materials and heat treatment with these steel base cases.
It’s gotta be rough on extractors designed around conventional cases.

My guess is on the initial firing extraction isn't bad, or worse than anything else. Even with steel there will be some spring back. Now if you exceed the strength of the chamber walls and get some expansion there then all bets are off.

 

[SKWERLZ]

My guess is on the initial firing extraction isn't bad, or worse than anything else. Even with steel there will be some spring back. Now if you exceed the strength of the chamber walls and get some expansion there then all bets are off.

Was thinking of it snapping over the steel rim repeatedly instead of a brass rim, maybe a moot issue but certainly could get interesting.

 

[DaveTooley]

Was thinking of it snapping over the steel rim repeatedly instead of a brass rim, maybe a moot issue but certainly could get interesting.

They have thought of that.

 

[Griffbl]

To add what Walt is saying….

The steel case head will start to ring the chamber after X amount of rounds at high pressure. I’d give you about 250-500 rounds and you will start to have extraction issues. Serious issues.

Also running it at high pressure on standard bolt guns… be prepared to use a dead blow hammer to open the bolt not just on the uplift but beating it back as well.

Also copper fouling will be an issue and effecting accuracy. To hold good accuracy you will be cleaning it about every 30 rounds.

Walt can correct me if I’m wrong but if I am… I’m not far off.

I have to agree with Walt… right now for the intended purposes of a military round with purpose built guns for that round is where it’s at and not for casual or target shooting in conventional guns.

Later, Frank
Bartlein Barrels

Frank-

I would like your opinion as to this: I will take it a s a given that the hybrid case junction of steel and brass is obviously "ringing" chambers at some point...Question for you Sir: Do you think Federal's approach (i.e. 7mm Backcountry) with an all steel case is a better solution for higher pressures than is the Hybrid case employed by Sig? Thank you so much. I appreciate your posts and inputs given your expertise.

Most Sincerely,
Brad Griffith aka Griffbl

 

[DaveTooley]

Frank-

I would like your opinion as to this: I will take it a s a given that the hybrid case junction of steel and brass is obviously "ringing" chambers at some point...Question for you Sir: Do you think Federal's approach (i.e. 7mm Backcountry) with an all steel case is a better solution for higher pressures than is the Hybrid case employed by Sig? Thank you so much. I appreciate your posts and inputs given your expertise.

Most Sincerely,
Brad Griffith aka Griffbl

Only time will tell.

 

[Straightshooter1]

Tried some H-4895 last month:

177 SMK's
45.5 grs H-4895
Case Fill: 95%
COAL: 2.977
Case Volume: 56.3 gr H2O *
Ambient Temperature: 93°F
AVG MV: 2,876 fps
Barrel: 26" 10:1 Krieger Heavy
SD: 7.1, ES: 23
QL Estimated Pmax pressure: 79,050 psi

Again, all cases extracted normally with no bolt lift issue and no pressure signs of any kind. While they all fired well and the results on target were decent (10 shots fired), this is more pressure than I need or want. But was an interesting test for this powder.

*Case head stamp on this one was "24", having less case volume than the previous I posted here.

 

[EricF]

From 233 rounds of hybrid SIG cases resized to 6.5 Creed. Weren't loaded super hot, most were 44 gr H4350 with 140 ELDs, about 2750 fps in a 20" CTR.

 

[Walt Krafft]

Yup. There it is.

 

[CJ6]

It's like nobody listens when somebody that helped develop the cartridge tells what's going to happen.

 

[FrankG]

Frank-

I would like your opinion as to this: I will take it a s a given that the hybrid case junction of steel and brass is obviously "ringing" chambers at some point...Question for you Sir: Do you think Federal's approach (i.e. 7mm Backcountry) with an all steel case is a better solution for higher pressures than is the Hybrid case employed by Sig? Thank you so much. I appreciate your posts and inputs given your expertise.

Most Sincerely,
Brad Griffith aka Griffbl

I think your dealing with two different scenarios. They Sig case is strictly towards a military grade weapon with parts built to handle it. Will see where it goes from there.

Fed's all steel case and I don't know all the details about it is geared towards the hunting crowd is what I'm thinking. Fed has shared some data with us and so far from what I've heard it helps with chambers and bolt thrust etc... but I don't have any more data at this point in time. If what I'm hearing is correct.... it would be an advantage for box ammo for the commercial market.

I haven't heard how reloading an all steel case good or bad though how it would work.

There are also some aluminum cases / ammo out there and from what I've seen and heard run really well but other than experimental stuff don't know if it's going to take off or not. The place that had quite a bit of testing done and seemed to work great but haven't seen anything in like 5 years.

 

[msalm]

Wonder if something as ‘simple’ as meloniting the barrel could ’possibly’ help w/ that ring formation…hmm. I couldn’t pass up the opportunity to at least play with it and ordered some to try in my 270-08 Ackley Improved…better order an extra barrel just in case

 

[Straightshooter1]

From 233 rounds of hybrid SIG cases resized to 6.5 Creed. Weren't loaded super hot, most were 44 gr H4350 with 140 ELDs, about 2750 fps in a 20" CTR.View attachment 1695490

It was suggested that it would be the hammering effect of the thinner part of steel part of the case against the chamber would create a ring. This doesn't look like any kind of "hammering" effect??? It appears to me to be more like gas leakage similar to what we see on a bolt face when gas leaks past primers???

 

[msalm]

It was suggested that it would be the hammering effect of the thinner part of steel part of the case against the chamber would create a ring. This doesn't look like any kind of "hammering" effect??? It appears to me to be more like gas leakage similar to what we see on a bolt face when gas leaks past primers???

Upon a closer look, I think you’re right. There really not an impression so much as an erosion ring. Surprising as with the pressure of firing I would think the pressure of the brass against that steel wall would seal.

 

[Straightshooter1]

Upon a closer look, I think you’re right. There really not an impression so much as an erosion ring. Surprising as with the pressure of firing I would think the pressure of the brass against that steel wall would seal.

Having just now looked at my chamber with a bore scope, I'm seeing that same kind of thing after 97 firings. Haven't run a bore scope there before and haven't done any cleaning since my outing last weekend. I'm convinced that this is from gas leakage burning into the steel as I see powder deposits on both sides of the grove:


After shooting last weekend, upon inspection of the Lapua brass I did notice what looked like a slight indication of case head separation on the outside of the case. The interior didn't show anything. But now, when I compare that hardly seeable ring on the case to the Hybrid cases, it lines with with that outer seam where the steel ends:


I'm going to give my barrel a good cleaning and look at that ring again, just to get a clearer view. I don't think it's very prominent yet for any serious damage . . . yet. You can even feel anything on those lines on the brass cases. But until there's some kind of solution, I won't be firing any more of these for a while (maybe when the barrel is shot out and I'm ready to throw it away ).

 

[CJ6]

Can you feel the groove in the chamber ?