Quick question about the crimping

[ADClope]

I've been trying to understand the various types of crimps and when they are to be used. This question, in my case, is in regards to pistol cartridges. My understanding is that a taper crimp does not actually crimp, but simply removes the bell created by the expander, and the roll crimp will actually "pinch" the case mouth into the bullet. The third type of crimp it seems like, is the Lee Factory Crimp, but I'm not sure which category this directly falls into as it seems to be a bit of a hybrid?

Also, I've been reading that you cannot roll crimp without a cannelured bullet. For my 9mm, I currently have just a standard 9mm 115 GR bullet with no cannelure and a set of Hornady dies that I'm using. They are the standard, custom grade, without taper crimp (so I'm assuming roll crimp, if you choose to after seating). Does this mean that I cannot crimp these bullets with my current seating die? Will I need either a Lee Factory Crimp Die, or a taper die?

I tried belling the mouth so that it just BARELY allowed the bullet to start, and then seated it to the recommended COL of 1.100, but when pressing the completed cartridge into the loading bench, the bullet did move back into the case, so it appears neck tension is not enough.

Just looking for some clarification on these things.

Thank you

[bbqncigars]

The dies should have come with setup instructions, but there's some good videos covering seat/crimp dies on youtube. I've loaded hundreds of 9mm using the traditional RCBS seating die. The Lee FCD is nice for some things, but a luxury not a necessity.

[Nathan]

A taper crimp has a mild conical shape in the die to crimp, but leave the mouth proud so it can headspace properly.

A roll crimp rolls the case mouth into the bullet, often hiding the case mouth partially.

A factory crimp is either a roll crimp or a taper crimp with a carbide sizing ring. The ring resizes the case with the bullet area of the case for better feeding, but may effect bullet fit to barrel.

Redding also makes a profile crimp for hard kicking revolvers. It is a roll crimp which is followed with a taper crimp to prevent buldging with a heavy roll crimp.

[DaleA]

Other folk are better at explaining stuff than I am. You might take a look at this thread.

https://thefiringline.com/forums/sho...d.php?t=395875

Note: the 9mm and the .45 ACP are two cartridges that headspace on the case MOUTH so the roll crimp is not used on them or they won't chamber correctly. The above thread has lots more information on this as to the reasons why.

[Nick_C_S]

My understanding is that a taper crimp does not actually crimp, but simply removes the bell created by the expander

Umm, yes. And no. That's an over-simplification. The inside of a taper crimp die is like an upside-down "V." The amount of crimp is dependent on how much you adjust it down. So yes, you can adjust it to just take the case mouth flair out. But you can also adjust it to crimp pretty darn hard (not recommended).

and the roll crimp will actually "pinch" the case mouth into the bullet.

Yes, it "pinches" or "rolls inward" the case mouth into a cannelure or crimp groove. To continue with my above analogy (with some trepidation), the inside of a roll crimp die is shaped like two upside-down "J's", facing each-other.

The third type of crimp it seems like, is the Lee Factory Crimp, but I'm not sure which category this directly falls into as it seems to be a bit of a hybrid?

Nope. A Lee FCD is a taper or roll crimp, depending on chambering. For revolver cartridges, it's a roll crimp. For semi-auto's, it a taper. What is different about a Lee FCD is the collar at its base that will "neck down" any irregularities in the case over the bullet. Whether or not the use of a Lee FCD is a good thing is a point of contention and spirited conversation. Opinions tend to be strong on each side.

There is also a Redding die - whose name escapes me - that supposedly does both. It taper crimps if you apply a light crimp; and it roll crimps if you apply it more heavily. I know little about it and have never used one. But those who have seem to speak highly of it.

I've been reading that you cannot roll crimp without a cannelured bullet.

Basically true. In the handgun world, roll crimping should be done into either a cannelure (usually jacketed bullet), or crimp groove (usually lead).

For my 9mm, I currently have just a standard 9mm 115 GR bullet with no cannelure and a set of Hornady dies that I'm using. They are the standard, custom grade, without taper crimp (so I'm assuming roll crimp, if you choose to after seating). Does this mean that I cannot crimp these bullets with my current seating die?

No. You may use your Hornady die to crimp. Your Hornady 9mm die set is likely a taper crimp. Generally, when you buy a die set for semi-auto cartridges, you get a taper crimp die. Subsequently, when you buy a die set for revolver cartridges, you get a roll crimp die.

I tried belling the mouth so that it just BARELY allowed the bullet to start, but when pressing the completed cartridge into the loading bench, the bullet did move back into the case, so it appears neck tension is not enough.

The neck tension may not have been enough. But it was less a function of how much you flaired the brass, as how little you crimped it. Sounds like you under crimped it. It's hard to know for sure, because if you push hard enough, any bullet will set back. I wasn't there.

I've been loading for over three decades. And when you've been doing it as long as me, you flair generously. I don't want to fight with a bullet to place it in the case mouth for seating. I want it to be quick and easy. So I flair a lot. It would seem I don't over work the brass by doing this; as it has caused no problems down the line. And although I don't spend a lot of time pushing seated bullets up against my load bench (no time, actually), I don't have any problems out at the range either.

Crimping is a "feel" thing with no substitute for experience.

[Nathan]

Speaking of crimp....in general, crimp hurts accuracy...in general...

So, how much crimp?

In auto pistol, I crimp the amount that gives minimal crimp and holds the bullet within 0-0.002" setback on 5 slide drops feeding from the mag.

On a revolver, I crimp test rounds in 1/4 turn on crimp die increments and check setback of the last round in the cylinder. Again, I'm targeting 0 setback.

[44 AMP]

9mm, I currently have just a standard 9mm 115 GR bullet with no cannelure and a set of Hornady dies that I'm using

What "standard" 115gr bullet are you using? Lead? Plated? Jacketed?

If you don't have the instructions, (or if you do and they are generic) call Hornady, and ask them. Give them the stock number of the die set and they can tell you what crimp, if any, is built into their dies.

For 9mm Luger, the seating die will have either a taper crimp, or none (so a separate crimp die must be used).

You CAN crimp into an uncannelured bullet, but you shouldn't, as it can distort the bullet, and even rupture the plating of plated bullets.

Some bullet styles (handgun, SWC, or wadcutter) can be crimped over the front driving band, if its the proper thing for that load.

On a revolver, I crimp test rounds in 1/4 turn on crimp die increments and check setback of the last round in the cylinder. Again, I'm targeting 0 setback.

I think the term you are looking for is "Creep" or "crimp jump", setback isn't an issue with revolvers.

[Nathan]

44, you're right...I was just thinking movement in general.

[mdemetz]

Lee's description of their revolver taper crimp die:

Lee 44 SPECIAL/44 MAG Taper Crimp Die, overcomes crimp problems caused by poor die design. Offers little or no advantage when used with 1986 or newer Lee Dies as the crimp angle is already a modified taper crimp


It sounds like their revolver crimp die is similar to Redding's?

[Unclenick]

The Lee crimps are shallower, at least in the CFCD's (Carbide Factory Crimp Die). The Redding Profile Crimp die is a roll crimp with a tapered leade from further down the case. This prevents the problem shown in the last position on the right which comes from using a conventional roll crimp seating die too hard, ironically reducing bullet pull force by causing the case neck to break contact with the sides of the bullet. The Profile Crimp Die lets you make very hard crimps without allowing that to happen. A friend of mine has a titanium frame short barrel .45 Colt that can't be used even with commercial ammo with more than a 200 grain bullet or the bullets jump the crimp. He needs a profile crimp die and a custom bullet mold with extra deep crimp groove to shoot 250 grain bullets in that thing.




ADClope,

What brand of brass are you using? Remington (R-P (Remington-Peters) headstamp) are famous for being so thin they get too springy upon resizing to hold a bullet well. I used to just toss them in 45 Auto because they wouldn't hold a bullet. The solution was Dillon dies which are small base as compared to standard dies, and narrow the cases more. Even if you aren't using R-P brass, that may solve your problem.