Is my taper crimp tight enough?

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slick001

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Can anyone help a new guy here work up a .45acp load?

I am trying to use a Rainier 230gr plated RN, with a once fired S&B case.

After I size it, I am belling it out to .473 on the expander.

Then, I have backed the Seating die back to where it seats it to the COL but does not do the roll crimp. .473 leaving the seater,

then going to a seperate taper crim, and crimping it to .468...

It still looks like it might need more crimp to me? I checked a factory loaded HP that is crimped to .471 and it looks way tighter on its bullet than does my .468 on my bullet...

Am I just being to anal about this or should it look like a tight seal after the taper crimp?

ps, haven't primed and powdered anything yet to shoot and try.

thanks :banghead:
 
That is more than enough. Neck tension holds the bullet. The "crimp" on an auto caliber is just to remove the bell or a hair more. It is not there to hold the bullet.

Here is one of mine.

attachment.php
 
If you'll look in your manual you'll see a .472" (12.01mm) dimension right at the case mouth. That's the maximum diameter that will go into the normal chamber.

45acp.png

So your reloads need to somewhat smaller than that number, say .470" or so. That should be enough. There is no "roll crimp" on a 45ACP, just the "taper crimp" with the square case mouth to headspace on the end of the chamber.

As Walkalong said, the taper crimp only cleans up the case contour at the case mouth. It does zero for holding the bullet in place. Here's an overly simplistic graphic to explain the difference between the 2 "crimps".

Crimps.png
 
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Interesting how the taper crimp is the only part touching the bullet in that fine drawing.
 
He can fix that easily. I love his drawings. I bet he did it that way for clarity of the crimp. :)
 
Calipers are minimally useful in determining crimp. They can help if you have a problem but for the most part are a waste of time having the reloader chasing numbers that make little difference. The goal of reloading is to make accurate ammo that works and other than minimum or maximum dimensions, measurements of things like the crimp mean little.

The crimping portion of the die does 2 things. It removes the belling of the case mouth and it pushes the side of the case mouth into or against the bullet to help hold it in place. How much crimp one should use depends upon how tight the bullet needs to be held. For semi auto cartridges you want the bullet held tight enough so that you don't get any setback when chambering. For revolver cartridges you want the bullet to remain in place under recoil. When using some powders you want the bullet held tightly to improve burn and reliability.

For your .45 acp loads the best way to determine if you have enough crimp is to use the "thumb test". Using thumb pressure on the base of the cartridge press the bullet nose against a hard surface, the edge of a bench works well. If the bullet moves back into the case then you need to add some more crimp. Adjust in small amounts by turning the die in or out and retest until the bullet remains firmly in place. With copper plated lead bullets its usually best to use the least amount of crimp needed so you don't "break" the plating.

For revolver cartridges a simple visual comparison to factory ammo is usually sufficient to see if there is enough crimp.
 
How much crimp one should use depends upon how tight the bullet needs to be held.
Click to expand...

Wrong. In semi-auto applications the crimp does not hold the bullet in place and has nothing to do with holding the bullet in place. It simply restores the case mouth to a shape where it does not interfere with feeding/chambering.
 
Hmmmm, I thought it was resized case neck applying pressure on the bullet that provided neck tension to keep bullet from moving.

Unlike roll crimp into crimp groove in revolver bullets, flat taper crimp on semi-auto bullet has little effect on neck tension.

Comments?
 
GI issue FMJ hardball & National Match ammo measures between .4695" to .471" from several different manufactures I have measured.
It varies only slightly due to differences in case mouth brass thickness from different lots and manufactures.

In all of them I have measured, pulled bullets show only a shiny ring on the jackets where the case mouth touched it tightly without cutting into or bending it.
That is a perfect taper crimp as done by the factorys.

My personal view is, if you can push a bullet deeper in the case by hand before taper crimping?
Your expander is too big and needs to be turned down a thousandth or two smaller.

Taper crimp does not hold the bullet in place.
It only provides for proper feeding and headspacing.
Proper neck tension is what keeps the bullet from moving.

rc
 
thanks for the pic.

ok , so pretty much between .470 to .472?

thing is when I am in that range , looking straight down the bullet from above, looks like i can see a bit of gap between the case and bullet.

maybe i need my calipers checked

it fits the LE Wilson max cartridge gage fine, but looks like a big gap to me.

Here is a photo of the gap at .470????

038.gif
 
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I think your caliper or the way you're measuring is off.
Click to expand...
Measure your bullet diameter to test. Rainier plated 45ACP bullets are sized at .451".

thing is when I am in that range , looking straight down the bullet from above, looks like i can see a bit of gap between the case and bullet.
Click to expand...
I think testing the accuracy of your caliper is what I would recommend as .470" taper crimp should bring the case neck tight against the bullet.

slick001, what's your OAL?

If your taper crimp is around .470" and your OAL shorter than 1.25", I think what you maybe seeing is not the gap between the flared case neck and bullet, but decreasing radius of the nose profile from the case neck.

If your caliper checks out and your OAL is short, then increase your OAL to 1.25"-1.27" and that gap should disappear.
 
918v said:
Wrong. In semi-auto applications the crimp does not hold the bullet in place and has nothing to do with holding the bullet in place. It simply restores the case mouth to a shape where it does not interfere with feeding/chambering.
Click to expand...
I agree 100%. I think the term "crimping" is confusing to new reloaders on semi-auto ammo. I call it "de-flaring" with a taper crimp die...
 
Taper crimp does not hold the bullet in place.
Click to expand...

Don't know where people pick up this nonsense. Its certainly not from practical experience. I have taper crimped both reloads and factory ammo specifically Speer Gold Dots to correct set back problems when feeding in particular handguns of mine. The bullets where indeed held in place by the taper crimp.

Theory: "Neck tension holds the bullet in place and not the crimp". Fact: Neck tension is the result of how tight the case fits against the side of the bullet and that fit is determined by the ID of the case. The smaller the ID the tighter the fit.

Fact: Taper crimp reduces the ID of a portion of the case against the bullet after seating.

Rational conclusion: Taper crimp increases the neck tension holding the bullet tighter.
 
bds
you may be a genius! I think you hit the nail striaght on the head.
the aol is 1.250 , i guess it is seating so deep getting into the roundness of the bullet itself. I found some load data for accurate 2 and this bullet, and that is the aol they called for.

Should I play with increasing the aol a bit to get the gap tighter, or leave it alone??? I test fired a few and they did cycle and shoot good
 
Fact: No amount of proper taper crimp on an auto case can make up for poor neck tension.

The crimp in .45 ACP is so light it does little to nothing to hold the bullet. Can it help? Sure, a little, but neck tension is 99% responsible for holding the bullet in place. That is what new reloaders need to hear. The crimp in auto's is not like the crimp in revolvers.
 
Rational conclusion: Taper crimp increases the neck tension holding the bullet tighter.
Click to expand...

Well, there's some evidence that excessive crimp can actually decrease neck tension, especially with lead bullets.

Rational analysis should include the difference in materials. Brass can exhibit "spring back", unless it has been annealed to dead soft. Lead really doesn't show this property. So, you can "size" the lead down during crimping, unintentionally, and have the brass return to a larger ID after the case is removed from the die.

rcmodel's advice on turning down the expander is correct.
 
I think your caliper or the way you're measuring is off.
Click to expand...

That statement is full of insight. Those based in metrology will tell you that accurately measuring a circular object is one of the hardest things to do. While we normally grab a set of calipers and are happy with the number, there are numerous situations that measuring 2 points on a circle will actually lie to you.

Measuring%20Round.png

To determine a true diametrical measurement, you either have to spin the object between centers or use a 3-point system, such as a V-block and a dial indicator. In the example shown above, we would all agree that the object is ANYTHING but round, but a 2-point measurement taken with a caliper returns the same reading at several places LEADING US TO BELIEVE it is round.

This is one reason that the ULTIMATE cartridge gauge is your barrel. When the auto cartridge drops in and out of your barrel under its own weight using the least possible crimp, then the crimp is correct.

Test on Tuesday. ;)
 
Adjustment of a Taper Crimp Die

Seat a bullet to the correct COL. Back out the seating stem. Then with the round in the fully raised ram, screw the die in by hand, crimping as you go. Can not over crimp this way if brass is all the same length. Final test, will round drop in to the barrels chamber? If not, a hair more taper crimp is needed. Or the COL might be to long.
 
Neck Tension & Taper Crimp

Well, there's some evidence that excessive crimp can actually decrease neck tension, especially with lead bullets.
Click to expand...
A taper crimp die would have to size a lead bullet down more than .005" to cause a problem with neck tension. Lead will "spring back" only so much. If you buckle the case, then this is a different problem. Brass and bullet jackets are not the exact same alloy, but close. See "BULLET DRAW DIES" for spring back/.005" http://www.corbins.com/drawdies.htm#brd
 
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