Brass casing lodged in chamber. Extractor ring ripping off.

[MEHavey]

While W760 is slower than, say IMR4895, the port pressures "ain't that different"
- Using W760 to achieve 55,000psi in chamber, the pressure at 7" port is 29,204 psi
- Using I4895 to achieve 55,000psi in chamber, the pressure at 7" port is 29, 209 psi
(You guys tell me the actual port location)

Question & Observation:
Q-1. Does the rifle have an adjustable gas regulator (like Ruger's SR762) ?
O-1. Failure to extract doesn't explain "stuck" case with no other pressure signs.

 

[bfoosh006]

While W760 is slower than, say IMR4895, the port pressures "ain't that different"
- Using W760 to achieve 55,000psi in chamber, the pressure at 7" port is 29,204 psi
- Using I4895 to achieve 55,000psi in chamber, the pressure at 7" port is 29, 209 psi
(You guys tell me the actual port location)

Question & Observation:
Q-1. Does the rifle have an adjustable gas regulator (like Ruger's SR762) ?
O-1. Failure to extract doesn't explain "stuck" case with no other pressure signs.

But... the duration of the pressure matters as well.

 

[Nature Boy]

But... the duration of the pressure matters as well.

this is what I understand as well

easy to rule it out, just make some moderate loads with a faster powder and see if the problem is resolved

 

[Blue68f100]

Are these reloads or factory ammo?

 

[BushMaster-15]

Easy enough to rectify , Clean Your chamber GOOD , Then Load #5 with 47.0 Gr. ,Load #5 with 47.5 Gr. and #5 more with .48 Gr. fire in mixed order . Just keep track of Which cases are which and see what gets sticky . Primers aren't always the best indicator of pressure signs .

 

[gwpercle]

For the AR10 rifle you may be using too much of too slow a powder for the semi-auto action .
The large amount of burning powder may be causing an "over gassed " situation .
Try a different , faster burning , powder and don't load them so hot .
My book shows this load suitable for bolt action rifles and it is only 0.4 grs below red line Maximum (48.4 grs for 2500 fps is max. ) !
For the AR10 ... at least drop back to 46.4 for 2400 fps ... that might work better .
Gary

 

[conan32120]

Winchester 760 is too slow a propellant for an AR 308.

This is giving you excessively high port pressures and excessive bolt velocities.

Switch to a faster propellant,

this seems logical as in my mind the bolt may be trying to extract the casing before pressure drops enough for the brass to "let go" of the chamber

 

[MEHavey]

Still.... no explanations for stuck case yet.

 

[bfoosh006]

Still.... no explanations for stuck case yet.

IMHO... it is stuck because the chamber pressures are still to high , and the fired case has not been released from the chamber walls... and it is ripping the rim off while trying to yank it out... again at high pressures.

It is possible that there is a rough chamber as well.

The stuck to the chamber walls / rim ripped off is a common issue with steel cased .223 / 5.56 ammo in a over gassed AR.
FWIW.. The steel case doesn't contract as readily as a brass case after firing... mimicking what is happening here.

Most steel cased ammo used by ComBloc countries have a taper to the case, and that helps chamber release dramatically.