9mm crimp

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chacam
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9mm crimp

Post by chacam »

I will soon be loading 9mm with a 145 gr lead cast bullet. My brass is range brass and case lengths vary by +/- .005 or so. Using the Lee seating die, it seems like if I set it for oal, that some will be getting more or less crimp. Is that something i need to be concerned about? I am thinking that I set the crimp first and then the oal? Thanks!
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Re: 9mm crimp

Post by GasGuzzler »

Body sets crimp, plug sets OAL. I'm guessing they'll be long or have less powder room with such a huge bullet.

+/- 0.005" is a very small spread and should be no problem. You don't want much crimp if any on pistol cases that headspace off the mouth like 9mm.
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Re: 9mm crimp

Post by Ranch Dog »

I don't think .005" is going to be much of an issue. A 145-grain 9mm Luger bullet is probably .625" in length, I don't think it will move unless that powder is ignited. Really pay attention to your charge, as GG noted there will not be much usable case capacity and .1 of a grain is going to mean a lot.
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Re: 9mm crimp

Post by mr surveyor »

due to the taper of the 9mm luger, isn't it only about the first 0.15 inch at the case mouth of a properly sized case that has sufficient tension for proper bullet retention? The reason I mention this is that when I first tried my hand at reloading the 9mm with a Lee Loader kit I found that I had to flare the mouth enough to be able to load cast bullets ... it was a very tedious task to get the exact amount of flare to be able to seat the bullet without shaving lead, or too much flare and then nearly no case tension. It seems to me that due to the taper issue, the crimp on the 9mm actually is a part of proper case/bullet tension and not just for the sake of closing the mouth to ease feeding issues. I've had no problems loading 9's with standard Lee dies using the FCD to close them up, and sticking to plated or jacketed bullets. Then again, I'm more partial to loading the straight wall .45 acp and the fatter bullets - easier to handle. :)


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Re: 9mm crimp

Post by RBHarter »

Seat and crimp in separate operations . On the 9mm , really any auto , make up 5 dummies . No powder or primer just the case and the bullet of choice . Now seat them no crimp just short enough to put all 5 in the magazine with no fussing or wiggling . Now field strip and pull the bbl . Get your 5 rounds of dummies and a factory round and a fired round from your gun . Now the factory round should just fall in the chamber or Plunk . Next take the fired case and "feel" it's fit . Now this should give you a pretty good idea of where bottomed is in the chamber and how the chamber feels . Take an uncrimped dummy and drop it in the bbl . There is a chance at this point that you'll get a plunk . It is just as likely that you'll get a case mouth rub or the bullet nose or shoulder hitting the rifling or throat . Decide which and adjust as needed to get a fit some where looser than the fired case and tighter than the factory ammo .
Put your pistol back together and put the 5 now chamber correct dummies in the mag and cycle manually if all goes according to plan then they should all cycle freely .
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Re: 9mm crimp

Post by mr surveyor »

yes, they should all cycle properly and show no (or extremely little) bullet set-back from cycling.


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Re: 9mm crimp

Post by GasGuzzler »

Right, post the smart way. I made dummies for my P95 until they were too long to fit. Backed off then added extra powder after testing.
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Re: 9mm crimp

Post by Ohio3Wheels »

Auto pistol cases and the crimping there of is a topic that takes up a lot of band width on just about any forum you wander on to. As someone noted earlier with that big a bullet in the 9mm you probably don't need a crimp to keep it from "telescoping" as they cycle. That said you need to remove any bell you put on to get the bullet seated so you might as well apply some crimp. As too how much - you, your gun and your choice of components will be the determining factors. Me, I taper crimp almost everything that goes into my pistols and pistol caliber rifles and I don't rim 380, 9mm or 45ACP. They're either lost in the weeds or worn out other wise before they grow enough to need trimming. For the auto loaders I stay at or slightly under max list OAL to keep the bullet off the rifling and to fit the magazine. Short cases and head space can in extreme cases be a problem but in most pistols in good condition the extractor claw will hold the case against the breach face and allow ignition.
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