Chamfering vs flaring/crimping for 9mm?

[Centella]

Morning friends,
I have never flared or crimped my pistol loads, I've always only chamfered. I'm starting to consider flaring and crimping because of some issues I'm encountering. My question is, do you always have to chamfer the inner part of a 9mm luger case mouth even if you'll be flaring to accept the bullet?

Thanks!

 

[Walkalong]

I never chamfer auto cases like 9MM, but I do flare a little. If you don't flare, a light chamfer would be a good idea IMHO, but some folks
don't flare or chamfer.

What issues?

 

[CQB45ACP]

Morning friends,
I have never flared or crimped my pistol loads, I've always only chamfered. I'm starting to consider flaring and crimping because of some issues I'm encountering. My question is, do you always have to chamfer the inner part of a 9mm luger case mouth even if you'll be flaring to accept the bullet?

Thanks!

No you don’t have to and I suspect most do not.

I do but just because 1) I’ve grown accustomed to it, 2) I use only the same small batch of cases over and over so they’re chamfered, and 3) when I use .356” plated berry bullets they seem to be easier to seat.

When using .355” Extreme plated, like you I didn’t expand/flare nor crimp/remove flare. With Berry’s I do (M style expander).

 

[badkarmamib]

I have never chamfered for straight-wall rounds. Flare just enough to get the bullet to balance in the mouth, crimp just enough to remove the flare.

 

[IWAC]

Chamfering may or may not be "necessary", and is generally not needed except after trimming, to remove jagged edges, both internal and external, which can cut plated jacketing, and possibly cause chambering problems with rifles. YMMV

 

[243winxb]

do you always have to chamfer the inner part of a 9mm luger case mouth even if you'll be flaring to accept the bullet?

NO. RCBS M type expander is all thats needed. Great die set, less problems.

 

[TonyAngel]

I never did chamfer for any straight wall pistol cartridge. A slight flare to help get the bullet started and prevent shaving. I also taper crimp for semi autos. I like to crimp enough to prevent the bullet from getting pushed in when a mishap occurs.

 

[gifbohane]

I never tried it but I believe that seating the bullet without expanding (belling) the case mouth is all but impossible. Accidentally crushed a few cases where mouth was not belled.

I have never chamferred the case mouth

 

[Atavar]

The only time I chamfer is after I trim case length, which is seldom for straight pistol cases.

 

[Centella]

I never chamfer auto cases like 9MM, but I do flare a little. If you don't flare, a light chamfer would be a good idea IMHO, but some folks
don't flare or chamfer.

What issues?

Hey, thanks for the reply. I got 2 issues: one, some bullets have a hard time seating; two, with some rounds, the bullet will move if you push it with just a little bit of force. A believe a flaring die and Lee's factory crimp might fix these?

 

[Centella]

No you don’t have to and I suspect most do not.

I do but just because 1) I’ve grown accustomed to it, 2) I use only the same small batch of cases over and over so they’re chamfered, and 3) when I use .356” plated berry bullets they seem to be easier to seat.

When using .355” Extreme plated, like you I didn’t expand/flare nor crimp/remove flare. With Berry’s I do (M style expander).

Thanks!

 

[LiveLife]

What issues?

Yes, I am curious too.

Perhaps bullet tilting during seating? Differing amount of flare from different resized case lengths? Scraping bullet while applying taper crimp?

9mm ... I've always only chamfered

I never chamfer auto cases like 9MM, but I do flare a little. If you don't flare, a light chamfer would be a good idea IMHO, but some folks
don't flare or chamfer.

Same here.

For calibers that headspace off case mouth, I do not want to chamfer inside of case mouth because you are decreasing the surface area that can "headspace" with the chamber.

NOTE: I also use minimal to no taper crimp so case mouth/neck seal with the chamber faster for less gas leakage.

I have never flared or crimped my pistol loads

I have used just enough flare to set the bullet without tiipping/tilting during seating but problem is unless you sort resized cases by length, mixed range brass will produce different resized case length to result different amount of flare. (To address this issue when using mixed range brass, I measure sample of various headstamp brass and use shorter ones to set the flare amount so longer case will apply slightly larger amount of flare )

As to amount of taper crimp, I just return flare back flat on the bullet. To achieve this, I add average thickness of case wall to the bullet diameter. So for .3555" sized RMR bullet, .3555" + .011" + .011" = ~.378" at case mouth.

And as requested by their customer base, Lee Precision addressed these issue FOREVER (No need for flare, no bullet tilt/tipping, no bullet scraping) with stepped "M" powder through expander which, regardless of resized case length, eliminated bullet tilt/tipping issue during seating and indexing with inline bullet feeder die (No more fussing with flare amount and different resized case lengths) - https://www.thehighroad.org/index.p...-through-expander.916523/page-4#post-12725787

If you look at the zoomed in picture of RMR 124 gr FMJ loaded to 1.130" with .378" taper crimp, on the right side of case mouth, you will note sharp right angle of case mouth with gradual taper crimp following "tapered 9mm case" contour with even bulging of case neck at bullet base to show even neck tension - https://www.thehighroad.org/index.php?threads/thr-group-project-pistol-advanced-reloading-concepts-and-discussions.778197/p(age-10#post-11419509

These were minimally flared and deflared cases using old powder through expander with .378" taper crimp applied at case mouth (Note even bulging of case neck at bullet base to express sufficient neck tension ... None of these produced bullet setback)

These were used with stepped "M" style Lee powder through expander with .378" taper crimp applied at case mouth (Note secondary bulging at top of case neck to show "stepped" expanding but also even bulging of case neck at bullet base to express sufficient neck tension ... None of these produced bullet setback) - https://www.thehighroad.org/index.p...powder-through-expander.916523/#post-12569719

 

[Centella]

Yes, I am curious too.

Perhaps bullet tilting during seating? Differing amount of flare from different resized case lengths? Scraping bullet while applying taper crimp?


Same here.

For calibers that headspace off case mouth, I do not want to chamfer inside of case mouth because you are decreasing the surface area that can "headspace" with the chamber.

NOTE: I also use minimal to no taper crimp so case mouth/neck seal with the chamber faster for less gas leakage.


I have used just enough flare to set the bullet without tiipping/tilting during seating but problem is unless you sort resized cases by length, mixed range brass will produce different resized case length to result different amount of flare. (To address this issue when using mixed range brass, I measure sample of various headstamp brass and use shorter ones to set the flare amount so longer case will apply slightly larger amount of flare )

As to amount of taper crimp, I just return flare back flat on the bullet. To achieve this, I add average thickness of case wall to the bullet diameter. So for .3555" sized RMR bullet, .3555" + .011" + .011" = ~.378" at case mouth.

And as requested by their customer base, Lee Precision addressed these issue FOREVER (No bullet tilt/tipping, no bullet scraping) with stepped "M" powder through expander which, regardless of resized case length, eliminated bullet tilt/tipping issue during seating and indexing with inline bullet feeder die (No more fussing with flare amount and different resized case lengths) - https://www.thehighroad.org/index.p...-through-expander.916523/page-4#post-12725787

If you look at the zoomed in picture of RMR 124 gr FMJ loaded to 1.130" with .378" taper crimp, on the right side of case mouth, you will note sharp right angle of case mouth with gradual taper crimp following "tapered 9mm case" contour with even bulging of case neck at bullet base to show even neck tension - https://www.thehighroad.org/index.php?threads/thr-group-project-pistol-advanced-reloading-concepts-and-discussions.778197/p(age-10#post-11419509

Hey, thank you, that's great info. Good to know about the difference in case lenght by stamp..will implement that into my process

 

[LiveLife]

Hey, thank you, that's great info.

You are very welcome.

Good to know about the difference in case lenght by stamp..will implement that into my process

Actually resized case length can vary by headstamp but also vary by number of resizing and firing cycles as case length can grow longer with increased number of firing.

RCBS M type expander is all thats needed.

Yes, using stepped "M" style expander/powder through expander addresses the variance from resized case length issue along with other issues like bullet tilting/tipping during indexing/seating. (Now you can see why president John Lee jumped at immediate R&D of stepped "M" style powder through expander when I suggested while offered to beta test inline bullet feeder die ... And now, they are part of almost all of Lee Precision die sets ... "Ask and you may receive" )

 

[Jim Watson]

I flare generously so as to avoid scraping the bullet. I seldom pick up 9mm brass, no interest in "case life."

I do wish Dillon would join the "M" club. The aftermarket part I bought does not have enough step to start a bullet.

 

[Hugger-4641]

I use very little flare and light crimp with LFC die. Have never needed to chamfer 9mm.

 

[bihj]

The (should be) reason one chamfers a case is to remove the burr after trimming, it has nothing to do with bullet seating.

 

[N555]

Flare only.
No one chamfers case mouths on straight or straightish pistol brass.
I do a slight taper crimp then hit them with the lee factory crimp die.

 

[Soonerpesek]

I do wish Dillon would join the "M" club. The aftermarket part I bought does not have enough step to start a bullet.

If you haven’t already, try UniqueTek.com….
They have stepped powder funnels for the Dillon presses…unless that’s the aftermarket part you’ve used……then disregard the previous comment….

 

[CQB45ACP]

I never tried it but I believe that seating the bullet without expanding (belling) the case mouth is all but impossible. Accidentally crushed a few cases where mouth was not belled.

I have never chamferred the case mouth

With .355” Extreme 115RN I never expand nor (obviously) crimp. Quite possible.

 

[9mmepiphany]

Hey, thanks for the reply. I got 2 issues: one, some bullets have a hard time seating; two, with some rounds, the bullet will move if you push it with just a little bit of force. A believe a flaring die and Lee's factory crimp might fix these?

Neither of those issues are really exclusively a "flaring" problem.

Your issues as listed
1. unequal expansion due to differing case lengths. You can either set it for your shortest case and over expand the others or you can sort you cases by headstamp to lessen variances

2. Not enough neck tension is what allows bullets to be pushed into the case of a completed round. This is a sizing issue and correctly addressed by adjusting the Sizing die...or sorting cases to separate cases with thinner case walls

 

[Jim Watson]

If you haven’t already, try UniqueTek.com….
They have stepped powder funnels for the Dillon presses…unless that’s the aftermarket part you’ve used……then disregard the previous comment….

I was looking at those. My previous attempt was the DAA/MR Bulletfeeder version. Negligible step.

 

[LiveLife]

with some rounds, the bullet will move if you push it with just a little bit of force.

2. Not enough neck tension is what allows bullets to be pushed into the case of a completed round. This is a sizing issue and correctly addressed by adjusting the Sizing die...or sorting cases to separate cases with thinner case walls

Correct. Resizing die should "full length" resize to optimize neck tension. With ram lever all the way down, check the space between bottom of die and top of shell holder/shellplate. If you see daylight, die needs to come down further until there is no daylight. (If using progressive press, you may need to recheck for daylight while resizing with full shellplate)

And even with "full length" resized brass, if you apply too much flare with expander, you can actually increased resized case neck ID to decrease neck tension and produce bullet setback.

 

[Walkalong]

Hey, thanks for the reply. I got 2 issues: one, some bullets have a hard time seating; two, with some rounds, the bullet will move if you push it with just a little bit of force. A believe a flaring die and Lee's factory crimp might fix these?

You’re kind of thinking in the wrong direction. Neck tension holds the bullet, a proper taper “crimp” that only removes the flare won’t help. Neither will the magic FCD die with carbide insert, it could even make things worse. It has uses, but that’s another discussion.

Adjust the expander so the shortest cases get enough to start the bullet easily, which means the longer ones get a little extra, but will be fine unless you adjust it to far down for the shorter ones.

If after that your bullets move under light pressure your sizer isn’t all the way down (it’s a good tapered case), or the expander is too big. If you skip the expander and the bullet won’t move, the sizer is OK, but if it still moves, the sizer is too big

 

[ballman6711]

I chamfer and deburr new brass, or brass that's been trimmed. Once in awhile I'll see a piece of used brass that looks like it has a burr on the mouth and I'll give it a quick chamfer and deburr.

I don't bother otherwise.

chris