9mm plated keyholes and tumblers.

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sauer1911

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At the last IDPA classifier, I had a G34 9mm start to keyhole and or tumble bullets. :banghead:

I pulled apart some of the bullets and this is what I found.

Berry's 9mm 124gr copper plated projectiles
4.0gr titegroup powder
1.11-1.13 coal
pretty strong crimp, measured the crimp on the projectile at .345" the rest of it at .355"

I think that the close to max load, heavy crimp/loss of sidewall contact to rifling, and some coal that were rather short contributed to the problem.

Gonna try alot less crimp, and slow down to 3.9gr of Titegroup, keep coal to no less than 1.12"

Dont know the fps, didnt get to the outdoor range with a chrono.

be safe.
 
I've only had tumblers with 147gr plated in subsonic. I did read where only a very light crimp should be used with plated bullets. I only use 3.6-3.7 grs of Titegroup with a 124gr bullet.
 
.345" - .355" is too much crimp. With plated bullets, I use no more than .376" taper crimp.

You were likely cutting through the plating, reducing the bullet diameter, decreasing neck tension, etc.
 
the rest of it at .355"
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It's been a good while since I loaded a plated bullet. But I seem to recall Berry's measuring .356 and Rainier's measuring .355 1/2.

If you are after the maximum accuracy, it might be worth investigating. I like to keep my 9mm bullets are large as possible by using a 38 S&W expander plug. Even that plug measures only .354 at the end, but it's a lot longer and fatter than a normal 9mm plug, and it gives a deep taper to the case. It works fine with jacketed bullets, too. My Glock barrels seem to like cast/plated bullets at least .356 at the base, or greater. 355 1/2 seems to be borderline ok, too, although my data is far from comprehensive. This is somewhat of a hunch.

I recently made a super oversized expander for my 40SW, and I just shot my first batch of 40 caliber cast bullets through a Glock barrel with no leading. I'm shooting MBC bullets measuring .401 -.401 1/2, and I made the expander plug .400 1/2 - .401. The neck tension is plenty, even for .400" jacketed bullets, which is surprising.

For my personal 9mm Glock barrels, I find I need no crimp, at all. I don't quite remove all the flare, even. My 40/45 Glock barrels are more finicky, and I need to use a decent crimp.
 
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Glock's version of polygonal rifling doesn't seem to 'grip' the bullet as well as traditional land/groove cuts, and I suspect a slightly undersized and overcharged bullet will 'rattle' down the barrel.

My CZ 75 did this with undersized 355's until I discovered it needed 358's to grio the rifling properly.
 
Berry's 9mm 124gr copper plated projectiles
4.0gr titegroup powder
1.11-1.13 coal
pretty strong crimp, measured the crimp on the projectile at .345" the rest of it at .355"
Click to expand...
I'm also using Titegroup in my IDPA loads...aiming for 4.0grs, but settled for 3.95gr (average of 5 & 10 throws)

I'm using just enough of a taper crimp to remove the flare from belling the case mouth. The big difference is that I'm seating to a COAL of 1.135" (started out at 1.160")

Seems to be pretty accurate, still waiting to get out with the chrono to check consistency
 
with the day off, I am going to take the pulled bullets and tap them thru a barrel and see just how much rifling is on the deformed sides of the said bullets, then compare to lightly or no crimped bullets and the difference.

be safe.
 
You were likely cutting through the plating,
Click to expand...
This is a very real issue that causes plated bullet destabilization as the plating flies off under rotational stresses. After much issues with this phenomenon, I don't roll crimp plated bullets but only taper crimp them and usually set the crimp die down just enough to remove case mouth flare.
 
I am really suprprised that all the rounds chambered correctly at .345:confused: 9mm headspaces on the casemouth.

If you take a .355 bullet plus .011 x 2 case thickness and measure youshould at least get .377 depending on thickness of case.

As stated all of mine come in around .376.

check check and check again. Please let us know what you find out.:what:
 
I am probably not using the lingo correctly?

When I measure the outside of the cartridge/brass it is .376. When I pulled the projectile it measured .345 at the crimp mark. when I measured the area above the crimp it was .355. So the area of "crimp in" and lower was less than that.

So it would seem to me that there is a very small "ring" of proper width to seal the projectile as it travels down the barrel, allowing the area behind the seal to "wiggle" like a butterfly football pass.

Kinda like the passes from the Seattle Seahawks! YEAH :evil::what:

be safe
 
So the area of "crimp in" and lower was less than that.
Click to expand...
As long as you have full diameter on the BASE of the bullet, that seems to be the most important part for accuracy. This why I am obsessed with expander plugs when loading plated or softer cast bullets.

It's normal to make a shallow indent on the bullet when doing a taper crimp, even when you "just remove the flare." To remove the flare, completely, you need to "overdo" it a little, because of the springback. As long as you're not cutting through the plating or swaging the base of the bullet, this should be fine.

If you crimp in a separate step after seating, you will minimize the area of impact of your crimping indentation. If you're seating a shallow bullet to a long OAL, especially in 9mm that has a short case neck already, it is quite possible that excessive taper crimp can swage the base of the bullet, inadvertently.
 
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I load with an XL650, and the crimp is the final step in the press.

I had in the past merely set the crimp by feel, smooth and removal of the belled edge.

I now have it backed off to just smooth the cartridge back to parallel. Barely a crimp at all.

I will test how these run.

THANKS TO ALL FOR YOUR CONSTRUCTIVE INPUT! IT IS APPRECIATED. :):D

be safe.
 
sauer1911 said:
I am probably not using the lingo correctly?

When I measure the outside of the cartridge/brass it is .376. When I pulled the projectile it measured .345 at the crimp mark. when I measured the area above the crimp it was .355. So the area of "crimp in" and lower was less than that.

So it would seem to me that there is a very small "ring" of proper width to seal the projectile as it travels down the barrel, allowing the area behind the seal to "wiggle" like a butterfly football pass.

Kinda like the passes from the Seattle Seahawks! YEAH :evil::what:

be safe
Click to expand...
So you squeezed the bullets almost .020", (.376 to .355)? Nothing good could come of that. I'd like to think if I had set my press to do that, I would notice when pulling the handle.
 
sauer1911 said:
I load with an XL650, and the crimp is the final step in the press.

I had in the past merely set the crimp by feel, smooth and removal of the belled edge.

I now have it backed off to just smooth the cartridge back to parallel. Barely a crimp at all.

I will test how these run.

THANKS TO ALL FOR YOUR CONSTRUCTIVE INPUT! IT IS APPRECIATED. :):D

be safe.
Click to expand...
Crimping should not make a mark on the plating. Crimp just enough to remove the flare so it will fully drop in the case gauge. A roll crimp should never be used on 9mm.
 
Crimping should not make a mark on the plating. Crimp just enough to remove the flare so it will fully drop in the case gauge.
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I beg to differ. YOU may load that way. But depending on how big the bullets, how thick the brass, and how tight the chamber of the gun, one may need to leave a mark with the taper crimp. (Granted, the OP can probably use a lot less crimp.)
 
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Wow this is getting into minutae. :scrutiny:

The brass cartridge and the projectile are 2 separate things. The brass was always .376. when I pulled the projectile, the ouch part, it was crimped down to .345 from .355.

AS I stated earlier the key holing was found at an IDPA match. We shoot cardboard targets. not grain oriented newsprint that will tear with no backing.

I'm off to the range to chrono my new loads. seeya.

be safe
 
I've only had tumblers with 147gr plated in subsonic.
Click to expand...
Me too but maybe
You were likely cutting through the plating,
Click to expand...
and a .345" means over crimp. Not good when running them (plated of any kind) High like that. If your causing the plating to tear loose you can get a tumble.

With that smaller diameter bullet you may not be making a good seal of the bullet to the barrel either. Taking that heavy crimp out should take care of your issue IMHO.
 
Update from the range! ! ! ! !

Well, the 124 grain bullets with 4.1g of Titegroup and lots of crimp stunk!

The FPS varied in over 60 rounds from 600fps to 1127fps! Very erratic shot patterns, just a mess. And many, many key holes/tumbled rounds thru cardboard. :mad::barf:

NOW, with 147grains, 3.5g of titegroup, and just a slight crimp what a difference! 50 rounds with a variance of 926fps to 931fps! controllable groups, we are on the right road! All perfect lil round holes thru the cardboard!!! :D

I did not use more 124grain bullets because all I had was 147grain. The key so far is the crimp, less crimp and more contact with the barrel.

Be safe!!
 
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