WeiserBucks

1000 lb Elk are about as rare as a smart Democrat. OP, Take the 6mm, either of the bullets you talked about will work fine. Shoot em...

I for one print and carry my tax return for the past 3 years just in case a game warden wants to see that as well.

You describe 6% of game wardens. In my experience they're the worst form of LE in this country and would arrest their own mother for...

Do you carry around your approved 4473? Of course not. Quit making NFA items into some kind of mystical never never land golden ticket...

Tax stamp is just that, a tax document. It's not a permit or permission slip.

and Treasury agents

Luckily we don't live in east Germany and papers please get a laugh. Police cannot just ask you for paperwork on something that is...

Why SCI?

Shoot em where they should be shot and you'll be fine.

Unions…

Any of many that will accept a 3.9"+ mag box.

Custom rifles are seldom built to SAAMI specs for a reason.

Why send either back, when you can simply verify with a known solid scope? If the gun shoots fine with a verified functional scope...

With a 3.6 mag box half the bullet will be below the case neck junction?

For a 28 Nosler?