Adjusting crimp and bullet depth.


August 28, 2011, 08:11 PM
A few months ago, I bought a Lee Turret Press, and I am finally getting it set up.

I have the first two dies (Sizing and expander) set up, but I'm havign a hard time with the Bullet Seating/Crimping die. I figure seating depth is just a matter of trail and error until it seats the correct OAL (but if anyone knows a better way I'd love to hear it), but its the crimp thats giving me trouble.

1) How do I know that I'm using enough crimp?

2) How do I know if I'm using too much crimp?

3) Does the OAL effect the crimp? Obviously, there needs to be enough of the bullet in the casing for the crimp to "hold on" to, and I'd assume that in order for the cartridge to be short enough to fit in the gun, there would be enough of the bullet in the case, but we all know what happens when you just "assume" things....

4) What are the dangers of using brass that is of unknown origin? My Lyman manuel says not to use it, but my Lee manual doesn't say anything about it. I'd assume that means that Lee thinks its OK, but again, we know what happens when you assume things....


The load I'm planning on using (and trying to set the press up for):
115grain Jacketed bullet - starting with 7.9 grains of Accurate #7 - Min OAL 1.095

Thanks in advance,

Chris "the Kayak-Man" Johnson

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August 28, 2011, 09:00 PM
Your OAL becomes critical when you seat deeper than the suggested OAL for that particular bullet. A 9mm bullet seated .030" deeper than is recomended and drive pressures up to more than double. Speer did some testing and discovered a load producing 28,000 went to 63,000 with .030" deeper seating. So know your bullet and recomended seating depth, and stay at or above that number. Learning how to find the functing OAL for your firearm involves taking the barrel out and seating in small increments until you reach the depth that will fit the magazine and not contact the lands. When you drop a round in the barrel it should make a distinctive clink sound and should spin freely in the chamber without resistence, and it shouldn't leave marks on the bullet from contact with the lands. After having done this your OAL should be at, or longer than the published OAL for that particular bullet.
The crimp should be just enough to close the flaring after you've seated the bullet to the correct OAL. Excessive crimping will have an adverse effect on head space with most AL cartridges, 9mm inlcuded. 9mm and other simular AL cartridges head space at the mouth which is why you don't want to over crimp, it changes head space.
One more tip! Do your load work up near the minimum or starting charge watching for any unusual performance or signs on the brass that may indicate excesive pressures or other possible undesired function. Also, in my opinion you are going about this with the correct approach, including your choice of powder.

August 28, 2011, 09:17 PM
1> With jacketed bullets, the "crimp" is simply to remove the "bell" you put in. Approx. .378-.379" at the mouth after crimp. Use the minimum "belling" needed to set the bullet in the case by hand before using the seating die.
The "neck tension" the sizing die put in is actually what holds the bullet firm. 9mm uses a taper crimp.
2> Too much "crimp" will distort the bullet jacket. Follow the Lee die set-up instructions. Set the seating depth, then set the crimp, recheck both for needed tweeks. Measure the case mouth after seating the bullet to the correct OAL. .378-.379 is fine.
3> Follow the LEE die set-up instructions.
4> My recommendations When first starting reloading:, just use the big name-brand cases. Use either new or range pick-up cases. I suggest WIN, F.C., PPU, R&P, PMC, Speer, Blazer, *-*, or CCI to start. Others may not agree, but I also recommend sorting your cases by headstamp. This will give you consistent results with a consistent handle pull---some cases are 'softer' than others. Make things simple until you gain experience. Getting consistent OALs will be one of your first challenges.

What bullet nose-shape are you using? FMJ RN, JHP, JFP ? That oal sounds "short" but I didn't check your load against data. A FMJ rn/ball ammo is usually out to 1.12-1.145". Triple check your load data.

Stay safe, but enjoy the process.
You'll love shooting those first loads.

August 28, 2011, 09:29 PM
Here are some good crimp pics to go by.

Play with the die adjusted for no crimp to get your O.A.L., then screw the stem all the way up out of the way to adjust the crimp. It is not all that hard, but is the reason many like to crimp in a second step. Many, if not most, loads can be seated and crimped at the same time, but some combinations must be crimped separately after seating.

Loading 9MM is a breeze. You need just enough "crimp" to remove the belling or perhaps .001 to .002 more. I adjust the crimp so the shortest cases get the bell removed and naturally the longer ones will get some inward crimp.

I load 115 Gr jacketed or plated RN at 1.030 to 1.035 O.A.L. This works in my guns. Lead RN bullets are usually a little more blunt and will be a little shorter. Some folks load longer than that, but that is what I do. I just loaded some new to me Berrys 124 Gr hollw base round nose bullets. They are a little more pointed than the ones I am used to and I loaded them at 1.040 to 1.045 O.A.L.

If you load shorter than the load book, adjust your max charge down accordingly.

The "neck tension" the sizing die put in is actually what holds the bullet firm. Yep.

September 5, 2011, 06:24 PM
Thanks guys!

I don't think I articulated my questions about OAL very well. I was confusing the case length with the AOL, and trying to figure out if a longer case needed more crimp, but now that I've had a chance to sleep on it, it makes sense to me.

I think I've got it set up right. My test round looks close to a factory round that I was comparing it with, and the measerments are the same/similar.

Since this is the first time I'm shooting handloads in my gun, I jsut figured it would be worth checking one thing instead of making assumptions:
If I'm starting with the Load Manuals published Starting load, and a bit longer than the Min-AOL, that should keep the pressure down enough that even if my crimp is a little too strong (Although I don't think it is too heavy) my gun won't "Kaboom", correct?

Chris "the Kayak-Man" Johnson

September 6, 2011, 02:30 AM
Are you roll crimping for a revolver or rifle? Does the bullet have a crimp groove or cannelure?
Are you trying to seat the bullet and crimp in one operation?
Setting up to roll crimp, you need to get all your cases to the same length. If you are taper crimping for a straight-wall pistol case, don't trim your cases.
If you are trying to seat and roll crimp in one operation, you absolutely need to get all cases the same length.
When setting up your seating die, you need to first set the die body high enough that the crmp section does not touch the case mouth. At this point, using a case with no primer or powder, seat a bullet to the max COL (not the minimum referenced in the loading manual but the maximum SAAMI COL (go to the SAAMI site and download the cartridge drawing).
Now, if you have flared/belled the case mouth, you will need to adjust the seating stem all the way to the top on the die body and then screw the die body down until the crimp section touches the case. Lower the case and turn the die body in 1/8 of a turn of less. Run the dummy case back up to remove the flare and then lower the ram. Inspect the case to see if the flare is removed. Blacken the bullet and case mouth and try to chamber the round. The round probably will not chamber. Remove the round and inspect the blacking. If the blacking is rubbed off the case mouth, there is still too much case mouth flare. If the blacking is rubber off the bullet, you need a shorter COL. Seat the bullet deeper in small increments and check chambering. Once you get the COL such that the dummy round feeds and chambers, you should seat the bullet about 0.01" deeper for rifles and 0.005" deeper for pistols.
This will give you a decent COL for your gun and that particular bullet. Save the dummy rounds and label them so you re-set the dies for that bullet again.

Steve C
September 6, 2011, 03:01 AM
You are loading quite hot for a first time load. Check the current on line data from Accurate and you will find 7.9gr of No 7 with a 115gr jacketed bullet is a maximum load. Use a start load at least 10% below maximum for your first load and work up. Don't load a full box at the start load but load 5 to 10 test rounds, increase a 1/10 grain or two and load another small batch. When you've used up 50 cases with loads ranging from start to maximum take them to the range and test them starting with the lowest load and then the next higher. Test for accuracy in YOUR pistol and check the cases and primers for pressure signs. Stop if pressure signs appear as the previous lighter load will now be YOUR maximum. Select the load you will use at the best accuracy.

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