Crimping big bore rounds

How do I setup my crimp die? How do I know I have enough crimp? How much is too much, too little crimp?

Which crimp die do you use?

I use a Lee Factory Crimp die for my 375 Ruger. The easiest way to show how to set it up is there Youtube video.
There's a couple other videos out there to explain it well too.

My only suggestion is get a locking ring with a set screw from another die and set the ring so you don't have redo that each time you remove and install it on the press.

I crimp the 45/70 375 416Rem 416 Rig and the 458 Lott. All with the Lee crimping die. A better concept and I crimp in the crimping groove of the bullet by my eye based on experience of past usage.
Don’t over think it and you will be able to feel the crimp based on how hard the tool handle works. You do not need much effort.
I also crimp thousands of revolver cases each year and use the bullet seating die as supplied by the die people. Same thing do a few and you will learn by doing.
Good luck.

If you are using the lee die, I turn it in until I can’t wiggle the bullet anymore( in the die not the case) then give another 1/8 or 1/4 turn. If may sound weird but you will see what I mean.

Wyatt Smith said:

If you are using the lee die, I turn it in until I can’t wiggle the bullet anymore( in the die not the case) then give another 1/8 or 1/4 turn. If may sound weird but you will see what I mean.

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Wow! That’s not much crimp! Is that holding up to 458 mag or 505 Gibbs recoil?

Luvthunt said:

I crimp the 45/70 375 416Rem 416 Rig and the 458 Lott. All with the Lee crimping die. A better concept and I crimp in the crimping groove of the bullet by my eye based on experience of past usage.
Don’t over think it and you will be able to feel the crimp based on how hard the tool handle works. You do not need much effort...,,

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I do about the same, but was wondering if there was a more precise method. I probably over crimp a bit.

I use the Lee as I like its crimping action.

1. Take a sized and trimmed case and insert into shell plate.
2. Run the machine to full bottom stroke.
3. Back the seating stem all way off in the seating die, then screw the die body down onto the sized brass finger tip tight.
4. Seat the bullet in increments until you reach the cannelure or desired OAL.
5. Back the seating stem well off again.
6. With the operating lever in the full up stroke, (shell and bullet out of the die) turn down the die body about ⅛ of a turn, run it up into the die and check the crimp at the case mouth.
Note: You should not be experiencing any great resistance during this process. It should be a gentle bump like the sizing die and shell plate meeting at full bottom stroke when setting up the sizing die. IF YOU FEEL GREAT RESISTANCE...STOP AND BACK OFF THE DIE BODY. IF YOU FAIL TO DO SO YOU WILL CRUNCH THE CASE.
7. When you achieve the desired crimp, leave the cartridge in the die with the lever at full bottom stroke. Dial down the locking ring and tighten it to save the crimp setting. Dial down the seating stem finger tight onto the bullet.
8. With the lever at full top stroke and the die empty, tighten the seating stem just a tiny bit(slightly, just a squeak).
9. Load another shell to check the OAL.
10. Plunk test the cartridges in your rifle's chamber. They should slide in and out freely by gravity alone.

As has been posted- don't overthink it. I use a Lee Factory Crimp Die almost exclusively for hunting ammo. The Lee FCD is the one with the collet "fingers" visible from the top. The regular crimping shoulder on the inside of most seating dies can work for crimping, but are difficult to set correctly and have a tendency to decrease neck tension not increase it.

To properly use a Lee FCD. First, adjust your bullet seating die so the internal crimping shoulder barely touches the case mouth- then turn out an additional 1/2 turn so it won't touch the mouth of even a slightly long case. Set the lock ring on the seating die there. Seat bullet so the case mouth is up next to the FORWARD edge of the crimp groove or cannelure. (Note- you can use a Lee FCD even on a smooth sided bullet but you have to be gentle with the compression) Start the Lee FCD into the press. Run a loaded cart all the way up into the press. Turn the Lee FCD down until you feel contact. Lower the cart and turn the Lee FCD down an increment. Raise the cart up into the die again and watch the collet "fingers" compress around the case mouth. Repeat process of turning die down in tiny increments until the collet "fingers" completely close and touch each other. Set the die lock ring there. Any more compression of the collet die will unduly stress the die and press and won't gain any more crimp.

And to determine if you have enough crimp... simply load magazine full and shoot all but last round. Measure its length to see if any change. Do this two or three time for confidence in the test. Easy to do at the range during regular shooting session. Magazine rifles, both stacked and tube type, are prone to jamming rounds into case due to recoil thus shortening overall length. Double rifles and revolvers are prone to "pulling" bullets in the unshot barrel (or chambers) thus increasing overall length. Plus rough handling, by whatever circumstance, can change length usually by jamming bullets deeper into the case.

3 pics.
1st pic shows relaxed collet fingers before crimp process begins. 2nd pic shows full collet finger closure- crimping complete. 3rd pic shows usually the best location for a crimp.

nksmfamjp said:

Wow! That’s not much crimp! Is that holding up to 458 mag or 505 Gibbs recoil?

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It’s plenty for my 375 but it has good neck tension. A bullet with a crimp groove can use more than 1/4 turn.

nksmfamjp said:

Wow! That’s not much crimp! Is that holding up to 458 mag or 505 Gibbs recoil?

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This is basically what I do for my .458 Lott. I've also had a range session where I kept the bottom two in the magazine and never fired. Then came home and measured. No compression.

YMMV

I just loaded some .416 Taylor cartridges this evening using the older Barnes original 400gr bullets which don’t have a cannelure. I tapered crimped the case to the bullet. I don’t think the bullet is going to move as it seems tight? 70.0 gr of Reloader 15 for a medium load, we’ll see? I haven’t shot the rifle yet as I couldn’t find factory ammo.

fourfive8 said:

Note- you can use a Lee FCD even on a smooth sided bullet but you have to be gentle with the compression)

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How are you gentle with compression? Do you not allow the fingers to close?

Pheroze said:

How are you gentle with compression? Do you not allow the fingers to close?

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I do watch the fingers close when first setting up... so watching the fingers combined with the feel of the compression being exerted by the press are two gauges I use. Depending on the dimensions of the neck wall thickness, diameter of bullet or bottom of groove under the crimp and type of bullet- the fingers may not close all the way even though they have applied the correct amount of compression and deformation to the crimp. If it is a regular cup and core with standard copper jacket then you can put quite a bit more compression on the collet fingers because the jacket will deform underneath. Makes no difference whether bonded or not. Just depends on jacket thickness/hardness. However, if crimping into a monolithic copper or brass bullet, especially one that doesn't have a groove where you want to crimp or the groove is shallow, probably wise to be careful with the compression. You can feel the compression really build in those instances as the ram approaches maximum "break over" advantage on the press. Probably won't break the die but I heed the Lee warning about probably the cumulative negative effects on the die. Plus, I imagine any repeated high, peak stress at break over also tends to have a negative effect on the press over time.

458—-thanks I have been using the Lee crimping dies for years and never got onto the fingers approach.
Just proves you can teach an Old dog new tricks.

As you can see from the posts above there are two methods of crimping bullets. The original method called the Roll Crimp was used for years. The Lee Taper crimp / Factory crimp die came along later. I much prefer the Lee taper crimp as you are not seating the bullet while crimping it. Put another way the bullet is totally seated and stationary when using the Lee Taper crimp system.

Luvthunt said:

458—-thanks I have been using the Lee crimping dies for years and never got onto the fingers approach.
Just proves you can teach an Old dog new tricks.

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+1

Shootist43 said:

As you can see from the posts above there are two methods of crimping bullets. The original method called the Roll Crimp was used for years. The Lee Taper crimp / Factory crimp die came along later. I much prefer the Lee taper crimp as you are not seating the bullet while crimping it. Put another way the bullet is totally seated and stationary when using the Lee Taper crimp system.

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I like the roll crimp on anything that has a cannelure.
I like the FCD on 10mm, .300WM and old old .243 brass that has been over trimmed.
I have never felt it was difficult to set a die to seat and crimp in the same stage. There's lots of good information on die setup out there. I got mine from a precision rifle shooter's video.

I never said roll crimping was hard to do, I just don't like the idea of crimping the case mouth into a moving bullet.

When I roll crimp I do it in a separate step just like the lee die. When I seat the bullet I screw the bullet pusher a long ways down, so the case does not touch the crimp area. Likewise when I crimp I thread it all the way so it won’t touch the bullet.

Any decrease in accuracy?