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Thread: 9mm Overpressure Due to Crimping Too Tight?

  1. #41
    Boolit Master
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    Taper Crimping. Unlike a roll crimp, a taper crimp does not leave a radiused edge on the case mouth. A taper crimp simply flattens out the 'belling' that was previously done by the expander die, and squeezes the case mouth tightly against (but still mostly parallel to) the sides of the bullet.

    So yes it does put tension on the bullet. Try simply loading one round without crimping and see what happens. The bullet will move. Now put the bullet into the loader again and do a crimp and remove it. The bullet will no longer move if the crimp is correct.

    The Full length sizing die sizes the whole case back to spec. Once this is done the primer is expelled and a new primer can be installed. Once this has been acomplished the neck of the case is belled and powder is put in. From there a bullet is seated in the case and from there the the crimp die removes the belled case neck and crimps the bullet.

    This is the correct explanation.
    Last edited by 6bg6ga; 03-14-2018 at 06:43 AM.

  2. #42
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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. 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.
    Bingo.........

    Winelover

  3. #43
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    Well, I see the OP hasn't responded to all the additional information posted here.

  4. #44
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    Quote Originally Posted by contender1 View Post
    Well, I see the OP hasn't responded to all the additional information posted here.
    Does that surprize you? He either got upset over the responses not comfirming what he thought he knew or he was just bored.
    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.

  5. #45
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    unfortunate to see questions asked, then never revisited.

  6. #46
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    Quote Originally Posted by lefty o View Post
    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.
    it's a terminology issue that seems to trip too many people up.

  7. #47
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    Quote Originally Posted by Soundguy View Post
    it's a terminology issue that seems to trip too many people up.
    i guess, but my point remains...many people way over crimp. straightening the case puts plenty of tension on the bullet without actually crimping(bending the mouth of the case inward, actually indenting the brass into the bullet).

  8. #48
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    Quote Originally Posted by lefty o View Post
    i guess, but my point remains...many people way over crimp. straightening the case puts plenty of tension on the bullet without actually crimping(bending the mouth of the case inward, actually indenting the brass into the bullet).
    it's my opinion that people that started on rimmed cartridges, and didn't actually read a manual, and just reloaded as taught by 'dad' or the 'neighbor', and then they eventually transitioned into rimless cartridges, and they carried over the 'heavy crimp' they used on their magnum wheelguns.

  9. #49
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    Quote Originally Posted by xrayfk05 View Post
    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.
    Reading authoritative statements like this remind me of an old biker saying, " there are two kinds of riders, those that have laid a bike down and those that will". To relate it to the shooting world, "for those that don't crimp, there are two kinds of shooters, those that have had a KABOOM and those that will". I have instances where, while trying to feed a FACTORY round with a huge HP, the gun jammed, failure to feed, and the bullet had shifted. Therefore, I ALWAYS crimp , albeit, a very small amount but a crimp into the bullet nevertheless. That's just me. If one chooses not to crimp, well supposedly we are all big boys here and can make our own decisions.


    As far as the OPs none response, if I were on the receiving end of some of the smart "donkeyed" comments, I would not respond either. Some folks here have such a great insight into the human mind, they should team up with Uri Geller and take their show on the road.
    Liberals don't know they're stupid in the same way a fish does not know it is wet. It is just their natural state of being.

  10. #50
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    Quote Originally Posted by roysha View Post
    Reading authoritative statements like this remind me of an old biker saying, " there are two kinds of riders, those that have laid a bike down and those that will". To relate it to the shooting world, "for those that don't crimp, there are two kinds of shooters, those that have had a KABOOM and those that will". I have instances where, while trying to feed a FACTORY round with a huge HP, the gun jammed, failure to feed, and the bullet had shifted. Therefore, I ALWAYS crimp , albeit, a very small amount but a crimp into the bullet nevertheless. That's just me. If one chooses not to crimp, well supposedly we are all big boys here and can make our own decisions.


    As far as the OPs none response, if I were on the receiving end of some of the smart "donkeyed" comments, I would not respond either. Some folks here have such a great insight into the human mind, they should team up with Uri Geller and take their show on the road.
    Many people want to feel good about their ideas. They ask someone about their idea to get that feel good feeling and when someone doesnt agree with them they get hurt.
    Study of humans is interesting.
    Concerning crimp. I crimp jacketed and cast heavier than most when it comes to Semi Autos.
    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.

  11. #51
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    Quote Originally Posted by Soundguy View Post
    it's my opinion that people that started on rimmed cartridges, and didn't actually read a manual, and just reloaded as taught by 'dad' or the 'neighbor', and then they eventually transitioned into rimless cartridges, and they carried over the 'heavy crimp' they used on their magnum wheelguns.
    dont doubt any of that. see way too many people on the internet asking questions that are answered in every single reloading manual printed. those people cant be helped, as they dont want to help themselves. the rest of us can discuss things though.

  12. #52
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    Agreed. I see way too many new reloaders that haven't read a manual, don't own a manual, and get their data online from non official sources, don't work up loads, use others pet loads, etc.

    Its a wonder there aren't more kabooms.

    Of courst it does explain the broken pieces of guns and stocks I have seen at the range over the years, and the blown out cases where a smaller cartridge was held by the extractor claw then fired in a larger chamber and letting it partially bliw out and fire form the case.

  13. #53
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    He did appear to ask a question to be solved and when his disagnosis of high pressure was questioned and he was asked to provide loading information specifics he got miffed.

    It is true that taper crimping is no substitute whatsoever for proper case tension. It adds nothing to jacketed bullet grip, but may help with lead bullet retention IF it is applied to greater degree than most are willing to apply it.

    Said by a guy who has tested that and makes statements based on his findings.

  14. #54
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    A taper crimp does not add any tension on the bullet. It merely removes the bell put on the case to accept the bullet. Think about it... brass has spring back. Lead does not spring back. You get all the bullet tension from the sizing operation. This is one reason the manuals say to put just enough bell on the case mouth to get the base of the bullet started. No more, no less. I have tested round right out of the seating die (and before the taper crimp die) with the "push-against-the-edge-of-your-bench test" and they always pass with no setback. Try it.
    Looking for an RCBS A2 with the removable bushing. I need it to complete my A series collection. Please let me know if you have one you want to get rid of. Thanks!

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  15. #55
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    Saw mention of 9MM headspace here. Was looking for go/nogo dimensions for 9MM. Did not find so far. One loading manual I have state .750 CASE LENGTH for 9MM and another says .754. That said, I do not own a 9MM case that measures even .750 and I have a bunch. Some only a bit over .740. So say the go dimension is .754??? I'd bet some chambers are well deeper than that. Shoot a .745 case and expect a problem? I think not as I'm obviously doing it and have no problems at all.
    Have to think the extractor is holding the cases close enough to the breech face to where actual headspace means little. Otherwise a situation could happen to where the firing pin might not reach out far enough to fire the ctg.
    Interested to hear what others here think or have experienced.
    Re crimping. I seat bullets without crimping then use a second die in the last station of the Dillon to just roll in the remnant of the flair. The size die reforms the case enough t get good bullet pull.
    Pete
    Last edited by shortfal; 03-14-2018 at 10:34 PM. Reason: add. text

  16. #56
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    Quote Originally Posted by 35remington View Post
    He did appear to ask a question to be solved and when his disagnosis of high pressure was questioned and he was asked to provide loading information specifics he got miffed.

    It is true that taper crimping is no substitute whatsoever for proper case tension. It adds nothing to jacketed bullet grip, but may help with lead bullet retention IF it is applied to greater degree than most are willing to apply it.

    Said by a guy who has tested that and makes statements based on his findings.
    I'll have to diisagree that taper crimping does nothing for case tension. Sure you FL resize your case and then you bell the case so it will aid in installation of the bullet. Once the bullet is installed to the correct depth/OAL the case will need to have that belling removed. Sure you can remove the belling so the case is absolutely straight but I suggest that you measure the case OAL and then push on the bullet and see what happens. The bullet WILL move slightly. Add MORE tension as a result of slightly more taper crimp and the bullet will be held and will not move. If you think taper crimp does nothing then crank it down more and then use your bullet puller and see what the excessive use of the taper crimp has done to the bullet. Now you have made a ring all the way around the bullet. So, yes the taper crimp does help apply enough tension to keep the bullet from moving.

  17. #57
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    I suggest that those that don't understand how taper crimping works to read post #41.

    Taper Crimping. Unlike a roll crimp, a taper crimp does not leave a radiused edge on the case mouth. A taper crimp simply flattens out the 'belling' that was previously done by the expander die, and squeezes the case mouth tightly against (but still mostly parallel to) the sides of the bullet.

    Read the part where is says "squeezes the case mouth tightly against." If you still think it does nothing I suggest that you try moving the bullet prior to taper crimping it. It will move. Now, taper crimp it and it will not move. Taper crimp it too much and you WILL put excessive fore on it and you most certainly indent a ring around the bullet. So, if you think the taper crimp does nothing I suggest that you try the above and you WILL find that taper crimping DOES put pressure/tension on the bullet.

  18. #58
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    Quote Originally Posted by IllinoisCoyoteHunter View Post
    A taper crimp does not add any tension on the bullet. It merely removes the bell put on the case to accept the bullet. Think about it... brass has spring back. Lead does not spring back. You get all the bullet tension from the sizing operation. This is one reason the manuals say to put just enough bell on the case mouth to get the base of the bullet started. No more, no less. I have tested round right out of the seating die (and before the taper crimp die) with the "push-against-the-edge-of-your-bench test" and they always pass with no setback. Try it.

    Well I don't agree and have experienced this more than thirty five years ago. I use to purchase Speer Lawman Ammunition (125 JSP) for my Browning HP. That was the original source for the Speer 9 mm brass that I would reload with their 125 gr JSP's. My dies were and still are RCBS carbide. They came without their taper crimp die............which I purchased later. After numerous loadings, my reloads weren't passing the edge of the bench test, any longer. Until, I tried their newly released taper crimp die. Brass was literally given a new lease on life. Been using that die ever since, in a separate operation. I currently load for six different nines. BTW, 9 mm was the second cartridge I learned to reload, without anyone's mentoring. The first set of dies were 38/357 RCBS steel..................I learned about the advantages of carbide, after those.

    Winelover

  19. #59
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    My experience is like yours. I have 50 years reloading and I started out with 38/357 as my first caliber to reload. I then graduated to 45acp. my first 38/357 dies employed the roll crimp that simply rolls the edge of the case into the ring on the bullet. When I started reloading jacketed bullets I found a need to have a better crimp as the roll is worthless on jacketed. i then purchased the carbide dies and an optional tapper crimp die.

    I will attempt to over crimp a 9mm bullet and post a picture for those that are either unwilling to accept the fact that taper crimping DOES apply pressure to either a lead or JACKETED OR PLATED bullet. If you still cannot understand it or grasp the concept there is no hope for you in my opinion.
    Last edited by 6bg6ga; 03-15-2018 at 07:10 AM.

  20. #60
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    Click image for larger version. 

Name:	taper crimp too much.JPG 
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    Note the ring on the 9mm bullet. This is a result of too much crimp and as a result the pressure tended to push into the wall of the bullet. This ought to be enough proof that the taper crimp does exert holding pressure on the bullet.

    Where is that brass spring back now?

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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
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LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check