Taper Crimp .. How much is enough

[Bill in Ky]

I just got my taper crimp dies for my 9mm and my 45acp. As the title explains, how do I know how much taper crimp to put on these rounds?
Is it trial and error?
I have searched a lot on this site and I see people saying things like "light taper crimp" etc, but that's not much help to a rookie.
Thanks for the help!!

[GBertolet]

In the 45, many shooters like .469-.471 diameter at the mouth of the crimp. OK to go a little more if desired.

[pworley1]

I set mine to just tight enough to keep the bullet from moving under recoil. I believe that getting it consistent is the thing you are going for. Experiment with more or less for accuracy once you get enough to secure the bullet.

[rogerreloader]

If you are using jacketed bullets no more crimp than is necessary to make them feed reliable. If you are using plated bullets DO NOT crimp so much that it cuts through the plating. This will cause plated bullets to be very inaccurate. Feeling the transition from bullet to hull will tell you a lots. As smooth of a transition as possible without going too far(distorting the bullet). Hope this helps.

[Zymurgy50]

I use the barrel drop test for the 45. Pull the barrel and as you begin to adjust the crimp die down drop the round into the chamber. Only adjust the die down until the loaded round drops all the way into the chamber. Any more than that and you are swaging the bullet down in size.

[Mk42gunner]

For the .45, I set mine with a factory 230 grain hardball round. Screw the die down until it touches the factory round firmly and that is usually good.

It has been so many years since I loaded 9mm, I think I would try the same thing with it instead of trying to meet an arbitrary measurement.

Robert

[r1kk1]

Dimensions can be found on SAAMI and the Lyman cast bullet book as well as other sources.

Take care

r1kk1

[canyon-ghost]

A light taper crimp closes the case hard enough that you can't push the bullet back (try putting it on the bench and pushing down with both thumbs). It's light enough that there is a ridge for it to headspace on (you can feel it with your thumbnail). You should have about half the case thickness showing, or more, without buckling or bulging the case. If you'd have to pick up a hammer to move the bullet, you have a tight, light taper crimp. Chances are, a hammer wouldn't move it.

If it's too tight, the case will swell immediately behind it and give you some trouble chambering a round. After you waste a few dummy brass setting this crimp, you'll get a pretty good idea what it takes to set it. This is where you gain a little experience.

Good Luck,
Ron

PS: I reload with a trash can in the room, brass is easy to throw away. Might as well start with enough of it to experiment with. Brass, primers, lead bullets, etc. is all expendable and you can throw away experiments as long as there is no powder in the case. If there is, I use a copper tubing cutter to cut the case in half and pour the powder out before disposal.

[Artful]

For the .45, I set mine with a factory 230 grain hardball round. Screw the die down until it touches the factory round firmly and that is usually good.

Robert

I keep factory rounds for just this purpose in many calibers. It's good to have an ideal gauge.

[mdi]

I don't "crimp" my semi-auto reloads.I merely use a taper crimp die to remove any flare in the case mouth from expanding for bullet seating, to insure reliable chambering. I take the barrel of the gun to my bench and check chambering (plunk test) as I'm seating bullets and de-flaring. I use Lee and RCBS dies and neck tension has been enough to keep the bullets in place (jacketed, plated, lead, and PCed) shooting a 1911, a Ruger P90 (45 ACP), a FMK and a Tokerev in 9mm. A few thousand rounds of each caliber...

[W.R.Buchanan]

Bill: Post #2 has the correct answer. In the case of the .45 acp the crimp should measure .470 at the case mouth. All of the rimless cartridges have specific amounts that the crimp should be. When in doubt look at factory ammo, and what they do.

ALL FactoryAmmo is Crimped in some manner or another.

The .40 S&W should be .417-.418. Not sure about the 9MM but some reloading manuals do contain this information or you can measure a factory round and see what they did.

The monikers "light" or "heavy crimp" have more bearing on Roll Crimps used on Revolver Cartridges, Taper crimps have specific values.

Randy

[Airman Basic]

As others said, I don't measure, just taper enough to pass the plunk test, usually using my Blackhawk cylinder.

[Char-Gar]

I just got my taper crimp dies for my 9mm and my 45acp. As the title explains, how do I know how much taper crimp to put on these rounds?
Is it trial and error?
I have searched a lot on this site and I see people saying things like "light taper crimp" etc, but that's not much help to a rookie.
Thanks for the help!!

Bill...This really is an easy problem to solve. First of all you should taper crimp rounds for the 9mm and 45 ACP to shoot in the autopistol. Here is how you set it up, but you will need a factory loaded round of each caliber.

1. Put a factory round in the shell holder and run the ram up to the top of the stroke.
2. Screw the taper crimp die down onto the factory round as hard as you can using your hand only, no tools.
3. Set the lock ring on the die and you are done.

That really is all there is too getting a proper taper crimp on your handloaded rounds either jacketed or lead. As long as you bullets are seated to the proper depth for you barrel, your pistol will run with no problems.

I have loaded a quarter million 45 ACP rounds with every kind of case ever made and this has worked with all of them. Cast bullets are sized .452 but they have done just was well for me at .451 and .453. I don't believe I have ever loaded a jacketed bullet in a 45 ACP case.

I do not understand how some people can take something so simple and make it so complicated. Handloading ammo for either the 9mm or 45 ACP autopistol that will run as smooth as factory ammo is quite easy, but from reading this board, you would think it is rocket science.

[454PB]

I set it by feel. I screw the crimp die down to the point where it is way overcrimping, then apply the appropriate amount of pressure. There's no way to tell another person how much that is, I learned it by trial and error and measurement with a caliper.

Unless every case is trimmed to the same exact length, each round is going to have a different degree of crimp.

I don't know of many handloaders that trim pistol brass.

[wallenba]

First measure your case wall thickness, then double it. Add that figure to your sized boolit o.d.. Then subtract .002''. That should set the tension properly without sizing down most of the boolit in the process.

Example: Your case wall measures .010, double it = .020.
Your boolit is sized .452
equals .472
minus .002 = .470

Then just incrementally adjust the taper crimp die down until it measures .470

[Bill in Ky]

Excellent "How To"
Thanks


First measure your case wall thickness, then double it. Add that figure to your sized boolit o.d.. Then subtract .002''. That should set the tension properly without sizing down most of the boolit in the process.

Example: Your case wall measures .010, double it = .020.
Your boolit is sized .452
equals .472
minus .002 = .470

Then just incrementally adjust the taper crimp die down until it measures .470

[Love Life]

Lyman 49th and SAAMI have the info for those who may want to look them up.

[tazman]

Thanks for posting. I will look them up but for a 9mm not a 45 since I don't have one.

[John Boy]

Bill - the crimp on factory loaded smokeless powder rounds is your standard.
OK, how to measure ... take a factory round and put it in a kinetic bullet puller. Count the number of whacks it takes to remove the bullet from the case. The tighten the crip die on your reloads to match the whacks it took for the factory rounds.
Here's the standard I use:
3 whacks = light crimp
5 whacks = medium crimp
8-10 whacks = hard crimp
I whack on a lead ingot that is always on the bench

[MtGun44]

I set mine to about .466 or a hair tighter. Inadequate TC is one of THE MOST COMMON
problems with .45 ACP ammo causing jams (failure to close), and "too tight" causes ZERO
problems, too loose will cause ammo unreliability. I helped many IPSC shooters make reliable
ammo (no excuses in IPSC, one bad round can cost you a huge amount) for over 30
yrs and it HAD TO be reliable. There is nothing to be gained by TCing to .470 as is often
recommended (which is actually NO taper crimp at all), and a lot to be lost.

9mm is less of an issue, but again, a few thousandths "too tight" is safer than too loose.

Bill

[ackleyman]

Bill, Mtgun44 is dead on with my experience. In addition, if you shoot a custom 45acp with a target barrel, the tight TC becomes even more important. I had bad experience with a Barstow barrel on my Kimber TC to .470, reducing the TC to .468 ended that issue.

What is weird is that my cast bullets "normalized" in their OD after being loaded for a couple of years. Over time, the OD expanded as the cast bullet had retained the memory of the OD prior to being sized and lubed. The OD of some of the rounds expanded to .471 and those bullets caused me serious feeding issues in IDPA matches.

Also, I had to go through 3 taper crimp dies to get the die that I liked, and that Die was an RCBS.

On my 9's, I just give a slight taper crimp, have not mic'd the OD or had problems of any kind other than a large dose of AA#7 with the 124's is very accurate and will put unburnt powder in your face of a short barrel'd 9mm.