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40 Flare and Crimp settings


thegunnerd

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Hi guys,

Just curious what people tend to get in terms of measurements of their flare and subsequent crimp .

Do you measure it from the interior diameter of the exterior diameter of the case mouth? I just don't want to be over-crimping . I'm not seeing any dimpling on the bullet and i'm getting decent accuracy, this is more of a technical question to see what the general consensus is .

thanks !

Aaron

oh let me post some of the numbers i get

after resize before case mouth flaring .4175"

after case mouth flaring .4335"

after seating the bullet and crimping .4205

bullet diameter is exactly .4000" ( good quality control by x-treme bullets )

It's a 180 gr RNFP plated bullet seated to 1.805" for my 2011

Edited by thegunnerd
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Sweet Thanks Man .

Just wanted to feel out what people were seeing on their calipers . This is my first venture into 40 territory so i'm working out my load. What are you pushing it with?

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Sounds good to me. Just make sure to push the round against a table with your thumb and measure again to check that the neck tension is good and tight. Setback in .40 = bad things.

I'll check em right now , so far i haven't seen it happen with my rounds .........

I'm back from my bench.....no setback at all 1.1805 before and after . Sounds like a may be good to go. Now i need to chrono it and be done

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Just remember that the crimp is relative to the thickness of the case walls. If you get a lot (meaning group) of thin walled cases, your crimp may need to be adjusted. That said, the inside diameter of the case is what holds the bullet (as you probably know, but just saying for the noobs out there), and so crimp is always about feeding reliability and not about holding the bullet in place, at least in an auto pistol. Thin walled cases can certainly affect bullet setback, but a smaller sizing die and not the crimp is the way to solve that.

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Just remember that the crimp is relative to the thickness of the case walls. If you get a lot (meaning group) of thin walled cases, your crimp may need to be adjusted. That said, the inside diameter of the case is what holds the bullet (as you probably know, but just saying for the noobs out there), and so crimp is always about feeding reliability and not about holding the bullet in place, at least in an auto pistol. Thin walled cases can certainly affect bullet setback, but a smaller sizing die and not the crimp is the way to solve that.

Thanks man , that's a great explanation on what crimp is actually doing . For me i had just come across some info in dif places that was referencing crimp being such a by eye thing. Which is what i used to do. I'd flare a case enough to seat a round without marring the bullet , and then I'd run a flared case up then turn the crimp die down etc. but i recently got a new very accurate digital caliper and i got to thinking , what are some good numbers for a good amount of flare and then where to crimp to afterward . For me , i found i need to flare the case mouth slightly wider now that i'm using plated bullets . They tended to shave a little copper trying to seat in the same setting as the montana gold i had pressed. Of course over expanding is something to worry about with case necks cracking and then over crimping can be an issue too. I don't want to be caught with high over pressure or cases that don't chamber .

Luckily mine are chamber checking fine and firing fine already . I'm hoping to chrono it tomorrow and see what's what . Hopefully i won't have to adjust my recipe to make power factor

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