Fire-forming oddity

[RonnieMilsurp]

Could the extractor be forcing the base off center in the chamber?

Don't think so. It barely contacts it.

[RonnieMilsurp]

Plenty to pick from.

Attachment 316701

Thanks!

[indian joe]

Just did 2 more from fresh cases. Put about 1/8" of tape next to the rim to fill out the space in the chamber. Upped the powder half a grain, pre-trimmed the case. Fired exactly vertical. Got the exact same results. I even re-cast the chamber to make sure I'm not crazy, and it looks normal. Straight walls, just like Mr Springfield intended.

I am putting 6 grains of Win 244 (don't have Trail Boss or any shotgun powder) and filling the rest pretty tightly with corn meal, then capping with wax. The only thing I can think of is that the powder is still settling to one side when I chamber it, even though there shouldn't be much room for things to shift. It's definitely always the top of the chamber that doesn't expand for the first inch. Then it blows out evenly for the last .75".

Attachment 316674

If you use the tapered expanders you will get a much nicer result than those in the picture , plus save on primers and powder