Rifled Chamber?

[captainkirk]

I picked up a piece of fired brass (30-30) at the range the other day.  Whoever fired it was long gone, but I think it was likely a win 94.  The primer had backed out a little indicating a "springy" action, and there was a slight bulge above the case head on one side, but no obvious signs of over pressure.  The round appeared to be factory loaded (no die marks, etc.)  The odd thing is it sure looks like rifling marks are evident on the case.  They appear to have some twist and continue from the body of the case onto the neck, skipping the shoulder.  They also appear to have been "pressed" into the case body above the web when the case expanded to fill the chamber upon firing, and seem consistent with the rifling style and pattern in this type of rifle.  Anybody ever seen this?  I always thought chambers were cut after the barrel had been rifled, so I don't see how this could happen.  Just curious, there were several others lying around in the same caliber with the same markings, so it was not just one shell.

Thanks

captainkirk

[Mikey]

captainkirk:  Years ago I remember reading that the Heckler and Koch battle rifle in 308 left marks on the fired brass like that - I think they felt it would help battle rifles continue to function in extreme conditions.  I ahve seen brass fired from one of those rifles, and have seen that brass reloaded numerous times, all without ill effect.  However, seeing something like that in 30-30 is new (at least to me - lol).  Mikey.

[captainkirk]

I have seen some of the brass from the HK91 and its fluted chambers as well.  Generally, it is "smoked" along the flutes from gas moving around the brass.  I think it helps with reliability in getting a fired round out of the gun and another in.  That crossed my mind when I first looked at this case, but it looks entirely different.  It is as though the rifling has been "ironed" into the case...

[armory414]

Sounds to me like someone was firing .30-30 rounds in a gun of a different caliber--.35 Rem. or larger, possibly.

[captainkirk]

I forgot to mention that the brass looked completely normal otherwise.  Case head expansion looked normal for a 30-30, neck and shoulder were not blown out or blown forward.

captainkirk

[sgtt]

I believe the chamber flutes are to delay the action somewhat on self loading/ full auto, rifles/carbines.  I only witnessed this once on TC barrel that I had rechambered by a custom maker who had used the wrong reamer.