Crimp for 10mm in a revolver

[sparkyv]

So I've been using a standard FCD for 10mm for use in a 1911. Recently, started shooting 10mm in a revolver. Do I need to be concerned about crimp jump from the taper crimped rounds in a revolver? I haven't had the opportunity to test fire a dummy round in the revolver to measure the jump just yet. Maybe one of you guys has a simple answer?

[larryw]

Depends? On auto loaders, your need to concern yourself with bullet push back
due to the feeding process.
Revolvers, its bullet jump, pulling out of the case due to recoil, increasing COL & worse case,
Locking the cylinder tight. Do Not, underestimate either one of the above forces.
Do a " bench test " on your completed rounds. This is, measure, then push against
your bench really hard, measure again. Any, " Any" difference in length, a more
aggressive crimp is needed.
10mms in a revolver, especially if your are loading in the upper half of of the
charge data, in other words, warm to hot, I would for sure be trying different
degrees of roll crimp.. There you go, clear as mud right ? Oh yea, the exception
to the "bench test" are plated bullets. They are soft enough, lead core & plating
both, that a proper push test will deform the nose slightly, enough that you will think
you have push back when you actually dont.. I'll shut up & leave you alone now.
Sure hope this helps.
I know, I know RD ??? I'm going back to sleep now!!!!!

[Ranch Dog]

So I've been using a standard FCD for 10mm for use in a 1911. Recently, started shooting 10mm in a revolver. Do I need to be concerned about crimp jump from the taper crimped rounds in a revolver? I haven't had the opportunity to test fire a dummy round in the revolver to measure the jump just yet. Maybe one of you guys has a simple answer?

What Larry said. I would think the Carbide Factory Crimp Die has the best chance of providing a secure taper crimp. In a way, it is a bit out of your hands I suspect. I haven't looked but I doubt there is a way to produce the roll crimp as I believe all dies consider the SAAMI spec especially as to how the cartridge headspaces.

Hmmm... might have to take that back. I see that Precision Reloading offers a custom Hornady three-die 10mm/40 S&W die set with a roll crimp provided by the bullet seating die. Of course, they are out of stock.

[Macd]

My only experience with rimless cartridges in a revolver is with 45 ACP. No moon clips and they headspace on the mouth just like in a semi. Tapered crimp only. Does your revolver use clips?

[Ohio3Wheels]

Yep, I have 2 Black Hawk convertibles and both headspace on the rim for the 45ACP and 9mm and I've found that a crimp that works in the auto loader is fine in the single actions.

Stay well, be safe, make smoke

[Macd]

This I copied from an online magazine

For taper crimp, practical shooting reloaders have been doing it long enough to have hard measurements. Take the bullet diameter, plus twice the case wall thickness and then subtract .004 inch. As a general rule, and rough estimate, you can count on a handgun case wall being right around .010-inch thick. So for the .45 ACP, take a bullet of .452 inch, add .010 inch twice for a total of .472 inch. Then subtract .004 from that .472 and you get a goal crimp of .468 inch. Apply the same arithmetic for other calibers. A .40 or 10mm would be .400 plus .020 minus .004, which leaves us at .416.

Seems reasonable to me. I also make sure the expander diameteri n my sizing die is not oversize and case mouths are clean. Crimping will not overcome inadequate neck tension.

[larryw]

[/quote] Crimping will not overcome inadequate neck tension.[/quote]

Not arguing with you Mac, I agree 100% with the article, as a place to start,
& the last statement, which I totally agree with also but,,
Nope it won't compensate for inadequate tension, in some (read most)
Will straighten out, velocity ES, & most times will shrink groups.
Was just talking with Horseman today about this very same thing,
He tried it, then called me back excited at the improvement.
As well he should be, he worked hard at !! That's what its all about.
I'm going Michael, I'm going

[sparkyv]

Many, excellent responses. I will try the push test, and also a dummy round in the cylinder fired multiple times to measure crimp jump. I will call Lee to see if they can custom manufacture a 10mm collet crimp die.

I've shot several hundreds of my existing 10mm and 40S&W reloads without issue to date, but I need to look into this more to up my confidence in the taper crimp.

Macd, the M610 can shoot 10mm with and without moonclips. Also, I've never measured my tapered crimps. I'll give it a go.

Thanks, all.

[larryw]

Sparky, one more thing. When you build your dummy rounds for use "with" live
rounds to check for movement consider this.
Use fired, but resized brass, leave "spent" primer in the brass, charge with your
specific charge & seat a bullet to your specific COAL. Why?? Because, at the
levels of everything we work with while handloading, (pressires, velocities, mass ) ????
That little charge of x.x gr weight, under the extreme acceleration & impact
of recoil WiLL, absolutely make a difference??? Just another tid-bit for your files.
& YES, in this endeavor, very small, seemingly inconsequential things can,
& most times do, make a difference..

[Ranch Dog]

That little charge of x.x gr weight, under the extreme acceleration & impact of recoil WiLL, absolutely make a difference??? Just another tid-bit for your files. YES, in this endeavor, very small, seemingly inconsequential things can, & most times do, make a difference.

Larry made a very significant point!