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steve herman
07-23-2010, 04:00 PM
Just got into reloading and have some questions.

1- can a 380 round be loaded with a 9mm die set?

2-crimping,when to and when not to?

3-what effect is chrimping on pressure?

Thanks,

Steve H

Thanks for your help. Just ordered a set of Hornady 380 dies from Cabelas.

biometrics
07-23-2010, 04:14 PM
1 - NO not reliably... the resizing die is supposed to reform the brass to original dimension... not just the neck of the cartridge which is all you would do if you tried this. This is usually only feasible on bottleneck type cartridges that have been fired only in the gun where they will be reused. They headspace between the bolt face and the cartridge shoulder... the cases have already been perfectly sized by the firing process for that chamber.

2- you crimp when the projectile doesn't stay put when you have reloaded the case. You can't crimp the mouth of the .380 case because it is where the cartridge headspaces between the chamber and the bolt face.

3- A negligible amount - Don't worry about it.

-John

JanvanSaane
07-23-2010, 05:19 PM
I use a "Taper crimp die". It will taper a crimp rather than roll a crimp so the cartridge head spaces ok. Use it on both .45 and 9MM. Under heavy recoil I do not want any bullets pulling out of the case, or pulling the bullet out when the bolt slams forward. This may just be a personal preference but I have always taper crimped them. Jan

Rusty Marlin
07-23-2010, 10:30 PM
Just got into reloading and have some questions.

1- can a 380 round be loaded with a 9mm die set?


2-crimping,when to and when not to?

3-what effect is chrimping on pressure?

Thanks,

Steve H

1 and 2 have been answered adequately, but I feel 3 needs some clarification.

For Semi auto cartridges with or with out taper crimps, there is little to no effect. The powders used are very fast burning and don't require much resistance from the bullet to get a proper pressure curve with full combustion.

For large volume handgun cases like .45 colt, .44 mag and such, crimping can have a marked effect on the pressure curve, effecting complete burning of the propellant or not, and even the difference between sticking a bullet in the barrel with light loads or blasting them clear. With no crimp on these large volume cases when using med burn rate powders, like Universal clays, Blue Dot, Herco and such, the primer can dislodge the bullet, effectively increasing the volume of the case even more, before the powder starts burning and this will cause a light load to become a squib load.

With Slow burning magnum powders like 2400 or W296/H110 a heavy crimp is required to get the case pressure up high enough to get complete combustion of the powder. If not heavily roll crimped on light and medium weight for caliber bullets they can leave quite a surprising amount of unburnt powder in the case and laid like snow banks up the barrel.

For rifles... it depends... Auto loader: defiantly crimp, unless its a straight cartridge that head spaces on the case mouth, like the .50 Beowulf, .30 carbine, .351 Win....; Single shot: never crimp... unless it positively effects group size, them by all means crimp. On my .38-55 I don't even remove the bell mouth put on from the expander die.
Lever guns with tube magazines: always crimp.

huntinguy
07-23-2010, 10:30 PM
9mm is a tapered case. 380 acp is a straight case.

Steve points out the only type of crimp allowed on the more common self feeders. You can however over crimp... won't say how I know... but you can.

With the smaller pistol cases seating depth is critical for pressure. You will need a good reloading manual and a good set of calipers. It is easy to send a 9mm over sammi spec by seating too deeply.

if your expander is the proper size you should be fine, with most self feeders, to not crimp. I usually don't.

wooleybooger
07-23-2010, 11:46 PM
rusty marlin took the words right off my keyboard. i lightly taper crimp my 45acp and 9mil loads- both lead and jkt bullets. most revolver loads i put a heavy roll crimp on but i use slow powders and heavy for caliber lead bullets in those.semi-autos generally dont need a crimp if your dies are adjusted right and your bullets and brass are sized accordingly. i use a taper crimp in my autos because i may have 5-6 brands of brass in 1 box. uniformity on the OD makes for better feeding. in a revolver powder burn(pressure) is the reason for a crimp.

steve herman
07-24-2010, 02:43 AM
Thanks for the info

steve

deltaenterprizes
07-24-2010, 08:54 PM
A proper taper crimp straightens the flair made to allow starting the bullet in the case mouth. The bullet should be a press fit in the case of a couple thousandths.
I taper crimp all of my target loads for handguns. Heavy recoiling handguns should have a roll crimp to stop bullet movement under recoil.

Forestgnome
07-26-2010, 09:32 AM
1 and 2 have been answered adequately, but I feel 3 needs some clarification.

I agree. If I don't crimp 45 Colt when using 2400, I get a lot of powder blowing out everywhere and velocities are low and very inconsistent.

Farbmeister
08-19-2010, 10:03 PM
Wow, so wrong, but so sure of the answer.

A crimp performs several tasks.. but the order of importance is:

ENSURE A UNIFORM START PRESSURE.
Prevent Bullet movement.
Any other old wives tale about why you crimp.

A bullet is a press fit to the case. The resistance to the powder charge is a few dozen PSI with no crimp (aka a .45ACP round). The crimp is a UNIFORM resistance to the entire bullet to ensure that a much higher (a few 100psi) have developed.

Unless you are match loading, most cases and bullets are not round, so when you mate them under a press fit (no crimp) you can have varying differences in resistance to the initial powder charge. With a crimp, all that variance is taken away as the crimp is setting a defined resistance with the lip of the case into the bullet.

Ever wonder why they make crimps for bullets with no cannuelar? Or crimp rifle rounds? Not for the reasons others have listed.

Wow...