9mm OAL seating problem - The Firearms Forum

springerbuster · 11-15-2009, 08:03 PM

I have been loading 9mm in hollow point and round nose. I can't seem to get a consistent over all length. I have my seating die set for 1.160 (or so I thought). When measuring the lengths of my finished rounds I have lengths of 1.155 all the way up to 1.167. I am loading on a progressive press and the problem is there before I run them through a crimp die. How much deviation should I expect on a progressive press? I might add that I am using mixed brass, but even when I compare rounds from the same brass they are different lengths. Any suggestions would be appreciated.

gdmoody · 11-15-2009, 10:20 PM

Mine do the same thing so I can't tell you exactly what your problem may be but the 9mm head spaces on the mouth of the case so it needs very little or no crimp. If you don't go over the maximum length of 1.169 you should be OK. I set my caliper at 1.169 and each one that I load will be put through that caliper, if they go through they are good to go! I have the same problem with .45ACPs and I do the same thing with them.

312shooter · 11-15-2009, 11:11 PM

Several things come to mind, maybe try to increase the bell on the case mouth a hair, also the profile of both your seater plug and the bullet, I had the same problem using berrys bullets when I switched to Montana Gold they came out perfectly consistent.

LDBennett · 11-16-2009, 08:03 AM

There's an anvil inside the seating die. It is probably not ideally shaped for your choice of bullets and certainly will vary depending on the specific bullet you are using. A machinist or even the die manufacturer can make you a better anvil, shaped to your bullet of choice. The anviles are typical just flat across but a hemispherical dome shape may minimize the damage to the bullet nose.

If you have insufficient belling of the case mouth then you may be reshaping the nose of the bullet when you seat the bullet against the extra drag caused by the tight fit of the bullet going into the case. Hollow points are particularly bad about deforming as they are seated, as are soft lead bullets. Perhaps a better bullet is in order?.

But 9 mm requires a taper crimp and does not have to crimp into a groove or canalure. If the OAL of the finished cartridges does not exceed the maximum OAL spec you are OK. I know it seems funny to try to get everything just perfect when reloading only to have the bullet deform and make the OAL vary all over the place but they are OK to shoot. If you are concerned about ultimate accuracy you should change to a better harder bullet and make sure you belling operation is setup correctly to minimize the force required to seat the bullets. Perhaps a better shaped anvil will minimize any damage to the nose of the bullet. A call to the die maker may get you a better anvil shape or some good advice.

LDBennett

11-15-2009, 08:03 PM	#1
springerbuster V.I.P. Member Join Date: Sep 2009 Location: Southwest Washington Posts: 154	9mm OAL seating problem I have been loading 9mm in hollow point and round nose. I can't seem to get a consistent over all length. I have my seating die set for 1.160 (or so I thought). When measuring the lengths of my finished rounds I have lengths of 1.155 all the way up to 1.167. I am loading on a progressive press and the problem is there before I run them through a crimp die. How much deviation should I expect on a progressive press? I might add that I am using mixed brass, but even when I compare rounds from the same brass they are different lengths. Any suggestions would be appreciated. __________________ The second amendment was put there to protect all of the other amendments -->

11-15-2009, 10:20 PM	#2
gdmoody Advanced Senior Member Join Date: Sep 2007 Location: Northeast Georgia Contributor Posts: 6,407	Re: 9mm OAL seating problem Mine do the same thing so I can't tell you exactly what your problem may be but the 9mm head spaces on the mouth of the case so it needs very little or no crimp. If you don't go over the maximum length of 1.169 you should be OK. I set my caliper at 1.169 and each one that I load will be put through that caliper, if they go through they are good to go! I have the same problem with .45ACPs and I do the same thing with them. __________________ NRA Endowment Member GeorgiaCarry.Org Member Retired US Army Postal Worker Personally, I carry a gun because I'm too young to die and too old to take an ass whoopin'.....author unknown (but obviously brilliant)

11-15-2009, 11:11 PM	#3
312shooter Advanced Senior Member Join Date: Mar 2008 Location: Las Vegas NV Posts: 1,159	Re: 9mm OAL seating problem Several things come to mind, maybe try to increase the bell on the case mouth a hair, also the profile of both your seater plug and the bullet, I had the same problem using berrys bullets when I switched to Montana Gold they came out perfectly consistent. __________________ "Democracy is based on citizenship- perhaps the greatest gift the United States has given to the world- Power is vested in the people themselves, and government flows from the people" James M Henslin

11-16-2009, 08:03 AM	#4
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,754	Re: 9mm OAL seating problem There's an anvil inside the seating die. It is probably not ideally shaped for your choice of bullets and certainly will vary depending on the specific bullet you are using. A machinist or even the die manufacturer can make you a better anvil, shaped to your bullet of choice. The anviles are typical just flat across but a hemispherical dome shape may minimize the damage to the bullet nose. If you have insufficient belling of the case mouth then you may be reshaping the nose of the bullet when you seat the bullet against the extra drag caused by the tight fit of the bullet going into the case. Hollow points are particularly bad about deforming as they are seated, as are soft lead bullets. Perhaps a better bullet is in order?. But 9 mm requires a taper crimp and does not have to crimp into a groove or canalure. If the OAL of the finished cartridges does not exceed the maximum OAL spec you are OK. I know it seems funny to try to get everything just perfect when reloading only to have the bullet deform and make the OAL vary all over the place but they are OK to shoot. If you are concerned about ultimate accuracy you should change to a better harder bullet and make sure you belling operation is setup correctly to minimize the force required to seat the bullets. Perhaps a better shaped anvil will minimize any damage to the nose of the bullet. A call to the die maker may get you a better anvil shape or some good advice. LDBennett