Federal Peak Alloy 5.56

[Schmo]

The biggest thing I'd be watching out for is gas port pressure. If that pressure peaks too close to the gas port you can get ripped case heads, broken extractors, and excessive velocities on the moving parts, beating things up internally more. But if their powder spikes its pressure early and the pressure drops enough by the time the bullet passes the gas port, it'll be less of a concern.

It’s possible they’ll do it through powder selection, but also, regulate port size or go to adjustable gas blocks. I’m moving to adjustable gas blocks anyway for dialing in hand loads. I agree with Form. Don’t let Joe average determine where technology leads. If he’s ignorant and tears something up, that’s on him.

 

[JF_Idaho]

 

[djauofd]

I did go on Reddit and a similar discussion which involved the Alloy 5.56 am. Girsiele corporate account was answered some equations . I posed a question about thrust and recoil. I’ll let you know if the address an answer.


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[khuber84]

So listening to the shoot to hunt podcast Avery was talking to some the manufacturers testing the 7mm backcountry also in peak alloy. They reported that primers were protruding from pocket after firing. Not flattened from the very high pressure. This leads me to a thought. The steel case is gripping the chamber very well. Preventing rearward movement of the case during ignition, so much that the primers are able to move outward filling the headspace gap between bolt face and case head. This extra chamber grip may indeed be something that reduces bolt thrust.

 

[djauofd]

I’m thinking this is probably the case. No pun intended. If so, it would explain the thrust and pressure issue. However, as a consequence I think there will be a real possibility of chambering erosion as this thrust would be induced on the inside wall of the chambering.

If the case shrinks immediately as pressures drops, I would think it would be insignificant. This may be the case using higher speed powders, this would cause the initial higher pressure, but bleed off very quickly because all the propellant is being burned in the case and not being burned down the bore, which is basically how slower propellants achieve higher velocities while not increasing net pressure, as with say Alliant’s Reloder 17.

This would explain how the Peak Alloy 5.56 cases are able to function in a stock AR15 action. Of course my concern would be blown and pieced primers. Not much of an issue in a bolt gun, but problematic in a semi auto gas gun. As happened to me once in an AR10 the blown primer was bounced back into the chamber and as the next round went into battery the primer jammed the live round in place. Took a minute to get it out, had to disassemble the rifle back at my loading bench.


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