Should I be able to close a year old factory fitted barrel (44 mag) on a .005" feeler gauge between the breech and frame and it lock up perfect? And it does wobble without the forearm. I don't remember it being like this the last time I shot it last summer but it must have been.
can you clarify please, does it lock up with NO Wiggling? with or without forearm?
if it locks up with no wiggles, but can close on a 0.005 gauge, that won't matter UNLESS it closes on a 0.005 gauge with round in the chamber. Even then, it it fires 100% of the time, a straight case will usually not have any issues. Bigger concern with a bottlenecked cartridge that headspaces on the shoulder as you can get case head separation if you reload and full lenght size to any degree.
have you measured the headspace with a round in the chamber?
the space between the breech and barrel FACES have little to do with the safety aspect of shooting, from what I have read, and experienced, BUT that is predicated on the Chamber being cut correctly.
I have a 12ga shotgun that locks up solid as a vault, and I can darn near get a dime in there. But the Rim cut is fine for headspacing.
remember, space of 0.001 is a loose as a 0.005 regarding breech/barrel interface. As long as it is not wiggly when locked up.
Chamber headspace is a whole 'nother issue not really related to that measurment.