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Thread: 9mm Overpressure Due to Crimping Too Tight?

  1. #21
    Boolit Master

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    One more vote for seating depth. 9mms particularly spike in pressure if they are seated too deep. Use the same load but set the OAL to maximum. You will likely see a reduction in pressure indications.

  2. #22
    Boolit Master
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    Quote Originally Posted by DonMountain View Post
    The Hornady and Lyman Cast Bullet Manuals are obviously in error, so I will just ignore them too as being probably wrong.
    Where is the Hornady and Lyman manual does it say that the taper crimp on 9mm can cause pressure issues?

  3. #23
    Boolit Master
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    Quote Originally Posted by reddog81 View Post
    Where is the Hornady and Lyman manual does it say that the taper crimp on 9mm can cause pressure issues?
    They dont say that . He is just upset that he didnt get the answer that he wanted. We have all been that way at sometime or another.
    I have come to ignore long ago primer sign as a method to predict pressure as most have. I AM NOT SAYING it is not possible. Just that it is an UNRELIABLE way.
    The OP wanted answers that validated his opinion and when he didnt get them he was upset.
    We Know Mass Cannot Be Weighed But It Has Newtonian Weight And That Is Derived From Kilograms And Kilograms Can Be Converted to Pounds. But, Still Mass Cannot Be Weighed. But How is the kilograms obtained? Can Kilograms Be Weighed? Evidentally Yes It Can. But, Still Mass Cannot Be Weighed So Kilograms Must Not Exist. Funny Isn't It.
    One good thing out of this the next time I'm at the doctors and they want to weigh me I'll tell them mass cannot be weighed.

  4. #24
    Boolit Master
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    Even though the appearance of the primers may be unreliable to show pressure signs, it would show that something is different and then it would be up to the individual to seek out the cause. This could be a learning experience for others, or maybe the OP found his mistake and thought that was good enough. Some of the newer cases have oversized flash holes, some cases have the reinforced sides in the web area, and it is possible that some unknown debris got accidentally left in the case. That is of course just operator error. On the other hand, Cartridge OAL is also very likely part of the problem. There were a lot of suggestions and unfortunately ignoring the primer appearance is not really what was intended by that comment.

    Perhaps the OP is just taking time to work through the suggestions in an orderly manner and will update when the problem has been discovered. SWMBO might have other priorities and keeping things happy in the home is likely more important than updating a thread. Dusty

  5. #25
    Boolit Master
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    Quote Originally Posted by Dusty Bannister View Post
    Even though the appearance of the primers may be unreliable to show pressure signs, it would show that something is different and then it would be up to the individual to seek out the cause. This could be a learning experience for others, or maybe the OP found his mistake and thought that was good enough. Some of the newer cases have oversized flash holes, some cases have the reinforced sides in the web area, and it is possible that some unknown debris got accidentally left in the case. That is of course just operator error. On the other hand, Cartridge OAL is also very likely part of the problem. There were a lot of suggestions and unfortunately ignoring the primer appearance is not really what was intended by that comment.

    Perhaps the OP is just taking time to work through the suggestions in an orderly manner and will update when the problem has been discovered. SWMBO might have other priorities and keeping things happy in the home is likely more important than updating a thread. Dusty
    While you may be correct I choose to look at human nature. He never gave much info. Why? Like getting a doctor to diagnose a disease over the phone by telling him your sneezing a lot and taking aspirin but its not helping.
    What is wrong with me doc? Prescribe me some meds.
    We Know Mass Cannot Be Weighed But It Has Newtonian Weight And That Is Derived From Kilograms And Kilograms Can Be Converted to Pounds. But, Still Mass Cannot Be Weighed. But How is the kilograms obtained? Can Kilograms Be Weighed? Evidentally Yes It Can. But, Still Mass Cannot Be Weighed So Kilograms Must Not Exist. Funny Isn't It.
    One good thing out of this the next time I'm at the doctors and they want to weigh me I'll tell them mass cannot be weighed.

  6. #26
    Boolit Master


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    Quote Originally Posted by lefty o View Post
    you really dont need a "crimp". set the die to straighten the bell back out of the case after seating a bullet. that will almost surely give enough neck tension to hold the bullet fine.
    You are muddying the water.

    All the manuals call debelling a taper cartridge a taper crimp. ( vs roll crimp, etc. )

    Telling someone they don't need to crimp is counter productive, and blows the newbies minds that are reading and not posting.

    It should be fully understood by anyone that has been reloading for any significant amount of time that a taper crimp is reforming the brass to close the bell and provide neck tension on the projectile, vs something like the taper crimp that actually is rolling an edge over.. ( you could argue that's not a crimp too ), or vs a factory crimp that uses some fingers at the mouth to press inward.

    I cringe every time I hear someone tell someone not to crimp a (taper) crimp cartridge... because the person you are telling it to usually has low experience, and might not understand that YES, it does need a trip thru the crimp die..

    All the major manufacturers are calling the die a crimp die, and the manuals call it a taper crimp.

    to do anything else is just confusing the newbies.

  7. #27
    Boolit Master


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    Did he say anywhere what primer pressure signs he was seeing? flatenned? popping out?

    If he's on the low end and gettign primers unseating, he may simply be too low.

  8. #28
    Boolit Master
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    You can use a roll crimp die to straighten out the flare hence "taper" crimping. But a taper crimp die cannot roll crimp. Besides all the taper crimp dies ive seen says taper crimp on them.
    We Know Mass Cannot Be Weighed But It Has Newtonian Weight And That Is Derived From Kilograms And Kilograms Can Be Converted to Pounds. But, Still Mass Cannot Be Weighed. But How is the kilograms obtained? Can Kilograms Be Weighed? Evidentally Yes It Can. But, Still Mass Cannot Be Weighed So Kilograms Must Not Exist. Funny Isn't It.
    One good thing out of this the next time I'm at the doctors and they want to weigh me I'll tell them mass cannot be weighed.

  9. #29
    Boolit Master Texas by God's Avatar
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    Some of us are old enough to remember no such thing as a taper crimp die. For auto pistol cartridges that headspace on the case mouth the seating die squeezed the bell back to paralell. But as soon as I discovered the taper crimp die I got one in .45 ACP. Because they help.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  10. #30
    Boolit Man
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    I've had "pressure signs" on primers when no excess pressure was there from too much headspace. And also from gun oil in the chamber and/or on the case.

  11. #31
    Boolit Master redhawk0's Avatar
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    I remember in my early reloading days, I cast some 208gr WCs for my 44Mag. I was only loading for target shooting and the Lee 208gr did the trick....however, I found no loading data for that particular bullet design so I was...shall we say....winging it. I found loading data for a 220 or 225gr bullet (I forget now...30 years ago) and loaded to the low end for the powder weight listed for W-231. I had severely flattened primers, and some punctures.

    I started making some inquiries on the old castpic site and found out it was due to my seating depth. Since the entire boollit, except for the last 0.1", was pushed into the case (unlike the 240gr RN I was used to shooting)...the pressure was way too high for what I was trying to accomplish.

    Anyway...to make a long story short...I cut my powder back to 60% of those initial loads and they shot great, no primer flattening, no piercings...just a whole lot of fun at the range.

    So....without more information...I vote for seating depth as the culprit as well.

    redhawk
    Last edited by redhawk0; 03-15-2018 at 10:17 AM.

    The only stupid question...is the unasked one.


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  12. #32
    Boolit Master
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    Quote Originally Posted by Soundguy View Post
    You are muddying the water.

    All the manuals call debelling a taper cartridge a taper crimp. ( vs roll crimp, etc. )

    Telling someone they don't need to crimp is counter productive, and blows the newbies minds that are reading and not posting.

    It should be fully understood by anyone that has been reloading for any significant amount of time that a taper crimp is reforming the brass to close the bell and provide neck tension on the projectile, vs something like the taper crimp that actually is rolling an edge over.. ( you could argue that's not a crimp too ), or vs a factory crimp that uses some fingers at the mouth to press inward.

    I cringe every time I hear someone tell someone not to crimp a (taper) crimp cartridge... because the person you are telling it to usually has low experience, and might not understand that YES, it does need a trip thru the crimp die..

    All the major manufacturers are calling the die a crimp die, and the manuals call it a taper crimp.

    to do anything else is just confusing the newbies.
    settle down, i am not muddying anything. many people put way too much crimp on their cartridges, and it causes many problems. removing the bell puts sufficient neck tension on the bullet, and that is all that is generally needed. yes it needs to go thru the crimp die, but it really is not crimped.

  13. #33
    Boolit Master Grmps's Avatar
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    IF you were over crimping a 9MM,
    you would get leading to beat the band cause you'd be downsizing the boolit
    If you are getting bad leading you might be over crimping
    if no leading I would have to go with seating to deep or to much / hot powder

  14. #34
    Boolit Master
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    Ok,

    You do need crimp but just enough so that the bullet will not move if you place the nose of the bullet to the bench and push the case. I use my vernier caliper and measure OAL and then push on the case trying to see if the bullet will move in the case. I then re-measure the OAL of the round and see if there has been any change. If it moves then simply adjust slightly to obtain more tension.

    With respect the the OAL in the manuals..... I set up my length and then place the bullet/round in the barrel once the barrel has been taken out of the gun. The case needs to be even with the back of the barrel. If the case sticks out past then its too long and if its in too far its too short.

    Never seen a 9mm blown sky high but I have seen 40 cals that went to meet their maker.

    Pay attention to the load!!! Go according to the manual unless you have 50 or 60 years of reloading and really know what your doing developing a load from scratch. Always drop a load into a case and dump it into the scale pan and weigh it to see if your actually getting what you want in the load. I suggest that you weight about 10 or so to start and see if the load varies any. Once this is done and the load is indeed true then weight about every 50 or so. If using a powder dropper like RCBS and such use the same method each time otherwise the charge will vary.

  15. #35
    Boolit Master
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    I know I'd sure like to see the loaded rounds plunked into the barrel to see if the crimp is excessive, some pics of the fired primers & loaded rounds, in general more info, before I have enough data to have a solid opinion; Till then we're doing intelligent guesstimation, which might help get them to the answer but may not be "THE" answer.

    And I can understand the OP being a little upset at being told to ignore the hot primer signs etc. - I know if it were me I'd feel a few DOZEN twinges of paranoia, for good reason, at that point! I like my face the way it is, TYVM, don't want to need plastic surgery on it from pieces of a firearm slamming into it, and excessive pressures make me consider that a real possibility... Me no like!

  16. #36
    Boolit Master Forrest r's Avatar
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    9mm's are always interesting when it comes to reloaders and what so view as ok, not good, what to do, etc.

    [IMG][/IMG]

    [IMG][/IMG]

    [IMG][/IMG]

  17. #37
    Boolit Master
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    My OAL for a 9mm with X-Treme 124gr hollow point plated bullet is 1.083

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  18. #38
    Boolit Master
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    I don't believe I have adopted the so called plunk test. I simply put the round into the barrel and adjust OAL until the rim end is even like shown in the picture. Too shallow and there is going to be additional pressure. To long and your not going to get what I refer to as lock up.

  19. #39
    Boolit Master
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    After getting the length correct I then check to see if the rounds will load into the magazine. Never had a situation where the OAL was correct and the rounds wouldn't work in the magazine. Now, I haven't gone into too much detail with my explanation of OAL and crimp. What I have shown in the two pictures has always worked for me and generally is a little more length than what is possibly shown in some of the manuals.

    Obtaining just enough crimp is easy as I have mentioned. Just enough so the bullet won't move and your set and this is checked with either a vernier or a micrometer.

    Length as the picture shows the rear of the shell casing is flush with the end of the barrel as shown in the picture.

    I used to worry about the pressure. The 9mm round seems to have a tendency to flatten the primers more than some other rounds. I have been told by those in the know here not to worry about a primer that has flattened so I guess take out a quarter and flip the coin and settle on the answer you get.

    Anyway, you have my answers for what has worked for me for years. I've never blown up a gun so either I am very lucky or I might know what I am doing. Take your pick on the answer.

  20. #40
    Boolit Mold
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    Quote Originally Posted by 6bg6ga View Post
    Ok,
    You do need crimp but just enough so that the bullet will not move if you place the nose of the bullet to the bench and push the case.
    A taper crimp does not hold the bullet in place, that is done by the case neck tension caused by the sizing.
    If you can push in a bullet by hand you sizing die is out of spec or not setup correctly.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check