SAAMI cartridge specs / drawings downloaded long ago; updated periodically.next time look at sammi specs for chamber and case length. there is typically 15 thou MIN diff and typically MUCH MORE like 40.... just to prevent "normal" use from causing the problem.
sinclair sells slugs that go in a shortened case, you close the bolt and reopen. measure and have the ACTUAL NECK LENGTH OF YOUR CHAMBER, now trim based on that number. your carbon ring issue goes away.
I'm skeered to tally all the specialty handloading tools I got already. Dollar total would likely pay for the next $1K plus scope on my wish list. And there's nothin' like visual confirmation that, with MY firearms & personally trimmed brass, all is OK. And there's no guarantee that an individual firearm meets specs. Especially a factory-built one, as opposed to a reputable smith. But being human, even they can make mistakes.
It's good that we have the tools available that Sinclair, Short Action Customs, 21st Century and others - plus excellent stock, action and barrel makers - provide to us. I just can't afford ALL of 'em. ;~D
Having said that, a Teslong equivalent made stateside would be worth 2X to me. But I have zero idea whether that multiple is economically viable and the responsibility for making it happen is way above my pay grade.