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Thread: 9X19mm Crimp Die vs. 9X19mm (combination) Seater/Crimp Die - Thoughts?

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    9X19mm Crimp Die vs. 9X19mm (combination) Seater/Crimp Die - Thoughts?

    Like the title says.

    I have an RCBS carbide die set in 9X19mm with a taper crimp plug for the seater die for my current Dillon 550C. All of my 9X19mm loads will be for semiautomatic pistols, so nothing odd.

    Will I get any qualitative benefit from going with a dedicated crimp die in lieu of the combination die? Any safety issues? Yes, I've loaded and shot these before, with no apparent red flags/pressure signs as detected from the brass, just wondering if it's better to go with separate seater/crimp dies for this process.

    Regards,
    Pat
    Last edited by PatEgan; 01-23-21 at 03:11.
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    I prefer crimping as part of a separate step from seating. When you use the combination die, it is typically a roll crimp and reliant on the length of the brass. When loading mixed headstamps, the amount of crimp varies. I’d you use a taper crimp, there is enough wiggle room where all cases get a satisfactory crimp.


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    9mm is going to be a taper crimp anyway since the cartridge headspaces on the mouth of the case. The benefit of having a separate crimp step is so that you can seat the bullet fully before crimping otherwise you are still seating while crimping is taking place which could shave the sides of the bullet.

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    Back in early '70s I did testing in 9mm Luger,.45 Auto, and.44 Mag. In all cases, groups were smaller when seating and crimping were separated. Of course, unless you are actually shooting for accuracy at 25 yards or more, it may not matter.
    Testing also showed:
    1) trimming.44 Mag cases for uniform crimp had no effect at 50 yards and group size was slightly smaller for mixed length (not statistically significant). Later, I repeated for.38 Spl in S&W M52 and again found trimming had no effect even at 50 yards.
    2) trimming 9mm Luger cases hurt accuracy, I suspect due to increased head space gap. Groups with longest cases were slightly smaller than with shortest cases.
    3) varying degree of crimp for all three cartridges had no significant effect on accuracy at 25 or 50 yards
    4) with all three, accuracy was slightly smaller when COL minimized bullet to lede/rifling gap. All loads worked up from start load when COL was varied. Noticed no pressure effects from bullets being in contact with lede
    5) Like every one else back then,.357 jacketed bullets and.358 lead bullets were standard for Reloading 9mm Luger. There were no.355 bullets on gun store shelves and only 130gn.356" FMJ for.38 super were available.
    6) in.38 spl and.44 Mag,Redding Profile Crimp die gave best accuracy compared to any other roll crimp die I had.
    Last edited by noylj; 01-23-21 at 09:34.

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    Quote Originally Posted by PracticalRifleman View Post
    I prefer crimping as part of a separate step from seating. When you use the combination die, it is typically a roll crimp and reliant on the length of the brass. When loading mixed headstamps, the amount of crimp varies. I’d you use a taper crimp, there is enough wiggle room where all cases get a satisfactory crimp.


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    Not sure 'exactly' which RCBS dies OP has but my RCBS 9mm seater die does a taper crimp (if adjusted to do that). Not sure if they even make a 9mm die that does a roll crimp?

    100% agree with your comments about brass length and how it relates to that crimp.

    Most of my brass is Starline and they hold a damn tight tolerance on their lengths. Pretty much seat and crimp in one step on everything pistol if using that brand brass. If using mixed headstamp stuff I might be inclined to seat and crimp in two steps but...

    I still use the same RCBS die to do both operations with. I see no need for an extra special die just to do crimping when I already have one that will do that. Some guys will claim they like the second (crimping die) die so they do not have to 'readjust' anything but personally - I am just not seeing the 'difficulty' in making that tiny adjustment to the dies I already have. No matter what if you switch bullet types / profiles you are going to have to readjust things anyway so how much time really got saved having an extra die???

    I think the concerns about shaving bullets mentioned above are legitimate concerns if say loading lead or bullets with super thin jackets AND crimping the holy heck out of the rounds but otherwise - Not so much. Most of my pistol rounds I am only 'crimping' to remove the bell from the brass and iron things back out flat. May be called crimping but in reality it is not. Am not mashing any case mouths into any sort of canelure usually - The neck tension is holding the bullet in place well enough...

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    Quote Originally Posted by PracticalRifleman View Post
    I prefer crimping as part of a separate step from seating. When you use the combination die, it is typically a roll crimp and reliant on the length of the brass. When loading mixed headstamps, the amount of crimp varies. I’d you use a taper crimp, there is enough wiggle room where all cases get a satisfactory crimp.


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    This.

    I don't believe safety is a concern with either the combination or seperate dies.

    It does add a die change when you use a single stage press, kind of a pain. I use a turret press, so crimping seperately only adds a few seconds to each round. On a progressive press, I don't know if you would even notice.

    Andy
    Last edited by AndyLate; 01-23-21 at 09:34.

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    Quote Originally Posted by DG23 View Post
    Not sure 'exactly' which RCBS dies OP has but my RCBS 9mm seater die does a taper crimp (if adjusted to do that). Not sure if they even make a 9mm die that does a roll crimp?

    100% agree with your comments about brass length and how it relates to that crimp.

    Most of my brass is Starline and they hold a damn tight tolerance on their lengths. Pretty much seat and crimp in one step on everything pistol if using that brand brass. If using mixed headstamp stuff I might be inclined to seat and crimp in two steps but...

    I still use the same RCBS die to do both operations with. I see no need for an extra special die just to do crimping when I already have one that will do that. Some guys will claim they like the second (crimping die) die so they do not have to 'readjust' anything but personally - I am just not seeing the 'difficulty' in making that tiny adjustment to the dies I already have. No matter what if you switch bullet types / profiles you are going to have to readjust things anyway so how much time really got saved having an extra die???

    I think the concerns about shaving bullets mentioned above are legitimate concerns if say loading lead or bullets with super thin jackets AND crimping the holy heck out of the rounds but otherwise - Not so much. Most of my pistol rounds I am only 'crimping' to remove the bell from the brass and iron things back out flat. May be called crimping but in reality it is not. Am not mashing any case mouths into any sort of canelure usually - The neck tension is holding the bullet in place well enough...
    On a progressive press you will perform all steps simultaneously in separate stations. Therefore having two dies is necessary if not doing crimp and seating in one station.

    Shooting largely coated lead, it has been a problem for me attempting one operation; many times seeing shaved bullets or bulged cartridges that weren’t properly crimped/bell removed.

    You’re right, 9mm is typically a taper crimp. I read the OP half awake this morning and was making a general statement.


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    I never tried the combo die. Heard too many problem stories. I'm sure it could be made to work, but it strikes me that they should be separate based experience doing it separately.
    "What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v

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    Quote Originally Posted by PracticalRifleman View Post
    On a progressive press you will perform all steps simultaneously in separate stations. Therefore having two dies is necessary if not doing crimp and seating in one station.

    Shooting largely coated lead, it has been a problem for me attempting one operation; many times seeing shaved bullets or bulged cartridges that weren’t properly crimped/bell removed.

    You’re right, 9mm is typically a taper crimp. I read the OP half awake this morning and was making a general statement.


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    If I was shooting mostly coated (or plain) lead I would be doing it in two steps same as you.

    In my experience - With quality jacketed bullets, brass that is fairly consistent in length, AND if you are going for minimal on the belling and crimping... Shaving and crushing only happen when the dies are not adjusted properly.

    The more a guy tries to work (crimp) the case mouth beyond just ironing out the belling that was done - The more difficult it will be to get everything running smoothly in a single step with a single die. Your comments about the brass length / mixed headstamps and the amount of crimp applied were all spot on but become even MORE important as that die body gets turned down for more crimp than the bare minimum needed to iron out the belling that the other die did.

    I like my RCBS 9mm dies. They make a special seater plug for the Speer Gold Dot 9mm bullets which cost nothing but an email. Same seater plug works like a champ with many other brands of 9mm HP I tend to use as well but not telling RCBS that...



    I like the way they did the belling stems you get with many of their straight wall pistol dies. The tiny step before the major belling works well for me with the projectiles I like to use normally.



    With my dies this was the difference in size between the steps (and my craptastic sketch of the shape due to not having a macro camera here right now):



    The brass smears give a good tell of how that expander was adjusted and what it was doing to the brass it was used with in that session.

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    Quote Originally Posted by DG23 View Post
    If I was shooting mostly coated (or plain) lead I would be doing it in two steps same as you.

    In my experience - With quality jacketed bullets, brass that is fairly consistent in length, AND if you are going for minimal on the belling and crimping... Shaving and crushing only happen when the dies are not adjusted properly.

    The more a guy tries to work (crimp) the case mouth beyond just ironing out the belling that was done - The more difficult it will be to get everything running smoothly in a single step with a single die. Your comments about the brass length / mixed headstamps and the amount of crimp applied were all spot on but become even MORE important as that die body gets turned down for more crimp than the bare minimum needed to iron out the belling that the other die did.

    I like my RCBS 9mm dies. They make a special seater plug for the Speer Gold Dot 9mm bullets which cost nothing but an email. Same seater plug works like a champ with many other brands of 9mm HP I tend to use as well but not telling RCBS that...



    I like the way they did the belling stems you get with many of their straight wall pistol dies. The tiny step before the major belling works well for me with the projectiles I like to use normally.



    With my dies this was the difference in size between the steps (and my craptastic sketch of the shape due to not having a macro camera here right now):



    The brass smears give a good tell of how that expander was adjusted and what it was doing to the brass it was used with in that session.
    That’s the same die I use for applying my bell. I actually have the same set but have slowly swapped to a Redding competition seater and I’m also using the Redding crimp die. Buying the two I ended up with enough cost to justify the full set, and I prefer the Redding carbide sizing die, too.

    I mostly shoot action pistol and end up with a lot of bulk mixed stamp, so our applications are a bit different. These days I’m afraid there will be more and more coated lead as components are so short.


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