Calculator for measuring taper crimp

[Apple Man]

I always adjusted taper crimpers by that looks about right and dropping in a case gauge. I came across this the other day finding what pleases the case gauge is a moderate crimp .378 for the 9mm.

https://www.dillonprecision.com/crimp-calculator.html

[G W Wade]

Handy but just common sense. Have seen a lot of people crimping wat too hard. Remember one shooter complaining about his pistol not shooting very good. You could spin the bullet in the case with your fingers. Would be good for sone new reloaders GW

[Apple Man]

Handy but just common sense. Have seen a lot of people crimping wat too hard. Remember one shooter complaining about his pistol not shooting very good. You could spin the bullet in the case with your fingers. Would be good for sone new reloaders GW

Many Many years ago I switched from a roll crimp to a taper crimp on 38 specials. I had never used one of these before so I just cranked it down and loaded a bunch up. Well they shot terrible, come to find out I was sizing the boolits down with the taper crimper.

[higgins]

The SAAMI spec. for the mouth of a 9mm round is .3800 so you're awful close, probably within tolerance.

[jsizemore]

The powder funnel/expander for my Dillon 550b 9mm is .353. I size my 9mm bullets to ,357 cuz that's what the throats in my guns like. I went round a little with the fella that made me a custom expander/funnel cuz I wanted mine .356. That dillon expander was reducing bullets too much. He thought .356 was too big. We agreed that if it was too big I could chuck it in the drill and take a little diameter off. I polished it a little when I had reloaded the same lot of 3000 Speer brass for the 10th time. I finally had to scrap that brass after the 15th loading. Pulled bullets measured .3567. I shoot really fast burning pistol powder to ensure the bullet base fills the throat. Doesn't hurt that I only use 3.1-3.4 grains of powder.

When I measured the same lot of brass, case walls ran .010-.011. Crimp had enough adjusted tension that loaded rounds measured .377-.379 at the mouth. The Sig demands case mouths be less than .380. The new FC brass walls measure the same. The only difference now is the expanding is smooth when operating the press handle. The old brass was so work hardened that it wouldn't release easily from the expander and would leave a light sprinkling of fine brass flakes on the shell plate. I might need to swap in a slightly larger sizing die like a 38/357 carbide to reduce the brass work hardening even further.

[1eyedjack]

An article by Brian Pierce in Handloader refers to. 373 as a crimp dimension. I tried to duplicate that dimension and created some of the worst ammunition ever created! Swaged lead powder coated bullets down to .345 ish about as accurate as throwing rocks and left lead every where. Some failed to fire due to very light primer strikes possibly due to deep clambering? Sometimes we try to cure a problem that really doesn't exist!

[country gent]

A gauge to compare the crimp depth wouldnt be to tricky to make a 1" round body with a bullet sized bore and slight taper that matches the crimp from case dia to bullet dia Form you starting crimp and measure with the gauge on the round with calipers. Wouldnt be a true measurement but a comparison when you got the depth crimp you wanted it could easily be repeated with the gauge. With most digital calipers they can be zeroed along the scale at any point, zeroing on a case would tell you how deep you went.
Getting accurate repeatable dimensions on a taper is tricky with out an gauge.

The other way is to do it thru math. you know wall thickness. taper crimp an empty case to the .373-.380 dia minus wall thickness X 2 and you should be very close.

[jsizemore]

"Getting accurate repeatable dimensions on a taper is tricky with out an gauge."

You'll get pretty good at it if you practice with your tools.

[country gent]

Tool Maker and some gauge making for 35 years Started when I was 15 years old.

[hoodat]

Brass thickness is generally .012". Double that, and you've got .024". Add bullet diameter, say .356", and you're up to your .380".
If you set your taper crimper to provide even .001" less than your .380" diameter, you've probably got enough crimp. jd

[jsizemore]

Tool Maker and some gauge making for 35 years Started when I was 15 years old.

Not talking about you specifically. Talking about the rest of the non tool making crowd of which I'm one.

[justindad]

I crimp to the point where I can just start to see light between the case mouth and calipers.
*
I’m failing to attach a picture, so here’s a link to a previous post where I succeeded in attaching the picture: https://castboolits.gunloads.com/sho...=1#post5619821

[Bird]

I do not crimp the case mouth into the bullet, but just close the case mouth up to the bullet. I seat a .357+'' boolit into a case that is expanded to .355''. The .002+'' tension is enough to hold everything in place for my autoloader. Loaded 9mm using the above boolit in a winchester case gives me .377'' at case mouth.

[Bigslug]

1. Look at the case mouth dimension on the cartridge blueprint in your loading manual.

2. Taper crimp to match the blueprint.

Does it need to be any more complicated than that?