If they chamber properly, (and your load is safe) go ahead and shoot them.
I would point out that, while we talk about "rifle" and "pistol" cases, what we are really talking about here (case mouth flare) is the difference between bottle necked and straight wall (or nearly so) cases.
you flare a .45-70 case, just like you do a .38 Special, or a 9mm. So you can easily start the bullet in the case mouth, straight. (and straight matters, you shouldn't just "drop them in").
Serious cast bullet shooters often flare the case mouth of bottleneck RIFLE brass too. The Lyman "M" die is purpose made just for this.
How much flare is too much?? If the brass cracks, its too much. If you can't get it to go into the seating die, its too much.
Standard advice is to flare the brass only as much as you need to start the bullet, and no more. The more metals are bent, the more they work harden, become brittle, and break. The case mouth gets worked more than any other part, and its usually where pistol cases fail (crack).
Overworking brass DOES shorten case life, BUT it may, or may not make a practical difference. Other factors are also in play.
Crimp, how much, what type, if at all, etc. is a much discussed subject, and opinions vary widely. The only constants seem to be that cases which headspace on the case mouth should not be roll crimped, and that a bad crimp is worse than no crimp. Other than that, we...discuss things (aka argue
), a lot.
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)