Crimping 9mm and .40


February 18, 2012, 08:46 AM
What are your thoughts on crimping for these two calibers? So far I have only loaded the 9mm and will load some .40 this weekend.
The 9mm seems to seat fairly tight and I don't think recoil while in the magazine will move them.

What's everyone else doing?


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February 18, 2012, 08:49 AM
I use a Lee FCD for my 9mm.....never had an issue.

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February 18, 2012, 09:58 AM
Crimping cases that headspace on the case mouth is a poor choice of terms.

What you are really doing is removing the belling of the case mouth. The "crimp" does not hold the bullet in place, case mouth tension on the bullet holds the bullet in place.

A taper crimp die is normally used to remove the belling although there are other ways to accomplish the same thing.

In my opinion a Lee handgun FCD is a solution looking for a problem.

February 18, 2012, 10:11 AM
I have the lee fcd for 9 and 40. Don't really use it though. The neck tension on the brass after seating the bullet seems sufficient to me. If a bullet seems to slide into the case too easy I set it aside to test later. Testing is just me pushing the round against my bench to see if the bullet moves. If it does I use a bullet pulled and discard the brass.

The Bushmaster
February 18, 2012, 10:17 AM
I don't know cfullgraf. I do just a bit more then just remove the bell. I, also, put a light crimp on the case mouth to insure they don't hang up when entering the chamber.

February 18, 2012, 11:10 AM
Neck tension comes from friction between resized case and the bullet, not from taper crimp.

For semi-auto cases that headspace on the case neck edge, I use taper crimp with .020" added to the diameter of the bullet. Since case wall thickness varies from .010"-.012"+ depending on the headstamp, taper crimp with .020" added to the diameter of the bullet will result with either flat taper crimp or slightly negative taper crimp that indents the side of the bullet (see picture below).

So for 9mm .355" jacketed/plated bullets, I use .375" taper crimp. I do not have issues with the use of Lee Factory Crimp Die on jacketed diameter semi-auto bullets but do not recommend its use on larger diameter lead bullets (.356"+) as post-sizing of the larger diameter lead bullets may decrease bullet-to-barrel fit (especially if your barrel is oversized), increase leading issues and could result in keyholing (depending on the barrel groove diameter/powder/charge).

Note: Drawing not to scale

February 18, 2012, 11:19 AM
If a reloader flares judiciously, the shank of most 9mm or .40cal bullets stretches the case as much as it was flared, in effect flattening the flare against the bullet and negating the need for any intentional "unflaring" of the cases.

February 18, 2012, 11:45 AM
If you measure a varity of factory loads, you will find the following case mouth measurements, on average:

9mm = .376".
40 S&W = .421".

If you set your seating/taper-crimp dies to reproduce those measurements, you can't go too far wrong.


February 18, 2012, 11:57 AM
Good information, thanks for the replies

February 18, 2012, 01:02 PM
I always crimp any thing I load. Hand guns and longe guns.

February 18, 2012, 02:24 PM
bds and rcmodel have it nailed.

February 18, 2012, 03:04 PM
Without even looking, I would bet some where on page #1 is another post referring to AL cartridge crimping. Eventually someone is going to experience a serious falure the result of over closing of the belled mouth because they were trying to crimp the mouth.

An AL cartridge has the potential to get the mouth pinched from crimping which can easily cause pressures to go sky high. If the mouth is able to get past the point in the chamber it is intended to stop against by even a tiny bit, or head spaces on, it will get pinched, and to the extent that pressures could would likely get critical.

And a FCD more often than not just creates problems with neck tension for many newer reloaders. If a reloader is having problems with neck tension, they are either doing something wrong during resizing, are over belling, or possibly using the wrong size bullet. Case mouths should only be belled just enough to eliminate shaving, and then closed up to the same diameter as what it measures to just above the base of the now seated bullet. But if that mouth gets tapered, it will cause the bullet to get pinched in the mouth that can't expand, thus preventing the bullet from exiting unrestricted. In effect, this transforms an other wise normal cartridge into an exploding device, simular to a pipe bomb.

Since I don't load with lead, I have eliminated all belling of the mouths on all of my handgun cartridges. I just chamfer the mouths enough to allow for the bullet to start and seat without shaving or cross seating. I haven't had any problems with this method in the better than 20 yrs. I began seating like this. And I'm guessing my brass is lasting a little longer as a result too.

February 18, 2012, 07:48 PM
I agree with rcmodel with one exception, plated bullets.

The plated bullets I use (Berry's) are .356" dia (+/-). I've found a .3765 to .378" will work fine for all 9mm Luger jackets without leaving any marks on any of my pulled bullets. .377 is my optimum taper crimp. I usually load with range pick-up WIN cases.

February 20, 2012, 10:24 AM
Lee FCD has neer been a problem for me. I seat and crimp seperately and hae my dies set to produce ammo at factory dimensions.

February 20, 2012, 10:42 AM
We can debate the FCD for pistols all day, and we have.

As posted, neck tension holds the bullet in 9MM and .40. Any "crimp" is a taper crimp that just removes the bell or a hair more.

Since 9mm cases vary quite a bit in length, I adjust my crimp so that short cases get the bell completely removed, and others get a hair more. (.001 to .002 Max)

Many people make the mistake of think crimp on an auto caliber holds the bullet, and many put way to much crimp on them, to the point of causing problems.

The FCD for pistols crimps like any other, and can be adjusted wrong just like any other. it is the carbide ring that post sizes where to debate comes in.

February 20, 2012, 10:45 AM
Which is why people should adjust their dies to get rounds which match up with reliable factory specs rather than simply what "they" think is best.

February 20, 2012, 11:14 AM
There seems to be a lot of opinions on placing a crimp on a bullet. I found the same thing when I started loading for my 308/M1A. I don't really like to crimp other than 45 colt.
On my 308 die I slightly turned down the center mandrel so the neck tension would increase slightly as recommended by several M14 guys.
I set my 9mm die to take out any bell and the rounds performed well. I will do the same with the .40.

February 20, 2012, 12:20 PM
Use the expander plug to set neck tension and crimp to remove bell enough to allow cycling the SA properly. Lately I don't even crimp(actually I do, but only to reduce the bell on LONG cases), fired cases still have the bell. They cycle and HS properly in my 40 XD. 9mm is a different situation altogether, if your chamber is tapered..

February 20, 2012, 12:33 PM
The FCD for pistols crimps like any other, and can be adjusted wrong just like any other. it is the carbide ring that post sizes where to debate comes in.

= This comment is only for semi-auto pistol FCD =

I believe the FCD's carbide sizer ring's diameter was meant for typical jacketed diameter bullets (.355" for 9mm, .400" for 40S&W, .451" for 45ACP etc.) to smooth out any bulging of case neck from bullet seating for more "factory-like" finished reloads. Also, if the base of your case somehow did not get full-length sized completely (perhaps hot loads shot in looser factory barrel chambers that overly bulged the case base), FCD's carbide sizer ring will help further resize the overly bulged case bases to reliably feed/chamber (especially in tighter match barrels).

For me, the use of FCD for these purposes is fine but not for use with larger diameter lead bullets as the carbide sizer ring may post-size the finished case which results in reduced bullet diameter that decreases bullet-to-barrel fit. If you want to use the FCD with larger diameter lead bullets, you can either knock out the carbide sizer ring to use as a taper crimp die (to seat and taper crimp in separate steps to not shave the bullet when using heavy/negative taper crimp) or have Lee Precision replace the carbide sizer ring with a larger one (I think someone posted Lee charged $15 for this service but I would check with Lee customer service for current pricing).

Instead of using FCD "after" my rounds are reloaded (they stay in the die boxes), I do Quality Control check "before" my rounds are reloaded. During resizing, if I have a case that requires significantly more effort, I will do a barrel drop test with the tightest chamber I have (which are Lone Wolf barrels for me). If the case don't drop in freely, I will resize the case again until it drops in freely or it gets tossed in the recycle bin. You could use the FCD to "push-through" resize the overly bulged case with the knob removed as in Lee Bulge Buster ( but not 9mm which is a tapered case and wider at the base).

For me, if an overly bulged case is reloaded, it may not fully chamber in the barrel and I prefer to catch it before I reload it instead of "fixing" the case with the FCD.

OK, back to OP on taper crimping 9mm/40S&W cases.

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