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Helping a friend.....

She has 147 gn handloads that appear to be tumbling when hitting the paper. Holes are inconsistent looking. The barrel is clean. She hasn’t tried box ammo yet out of same gun but will.

You suspect the bullet is the wrong diameter? Would either too big or too small result in poor flight pattern?

Or could the round be going too slow?
 

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I had some plated 147s tumble when I tried a different brand. I don't recall the diameter difference.

Holes "inconsistent" "hitting the paper".
Loose hanging paper will give ragged holes.
Stiff paper targets or paper tight on cardboard gives cleaner holes. Look for. a grease ring all the way around.
 

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In my experience, there are four main causes for bullet tumbling: 1) bullet not at proper velocity for the barrel to stabilize, 2) Bullet not the right size to get stabilized, 3) twist rate in barrel rifling not right for bullet/weight to get stabilized, 4) bullet shank not long enough to provide enough twist to stabilize bullet. Most commonly available commercial bullets are of proven designs that eliminate #4, so the other three are the most common offenders. Other than that, a heavily leaded barrel can cause both accuracy and tumbling issues (because the bullet cannot properly engage the rifling) and cause increased pressure issues that can be detected over a chronograph with erratic velocities. Mostly the first three with most commercially offered factory loadings.
 

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What hand gun and who's bullets?

Not all barrels are created equal and not all bullets are either!

Look up the SAAMI specs for the 9mm it will give the barrel inside diameter.

Next use a micrometer to measure the bullet diameter after being pulled from a case. Some reloading techniques will reduce the diameter.

Bullet fit is very important a .355 barrel needs .356 or larger diameter lead, plated or coated bullets or tumbling may result. Jacketed should be OK at .355.

To get optimal performance I cast at .358 and size to .357 to get a .355+ barrel to perform. This bullet also performs great in 38 Super and .38 Spl. too! the lead I use is around 10 BHN and my lube is fairly soft.

Be sure that your barrel is "squeaky" clean before further testing.

Slugging your barrel may be required at some point but properly sized and reloaded bullets may solve your tumbling problem.

All the best in 2020,
 

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Being hand loads I bet they're over crimped too. if you have a bullet puller, pull one and see if its deformed below the case mouth.
 

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I have one pistol that exhibits signs of bullet tumble over 15yds. It's a 4" SA 1911 compact. My 147gr coated handloads that work perfectly in EVERY other 9mm handgun we own, don't seem to be suited to that pistol. This spring/summer, I'm going to work up some 115 and 124 gr. loads at the same Power Factor to see if that cures the issue by having more velocity.
Too cold now.
 

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Probably over crimping on the plated bullets.

Crimp just enough to meet the SAAMI spec at the case mouth. In the case of 9mm, that's .380, maybe down to .377.


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See Post #4!

Probably over crimping on the plated bullets.

Crimp just enough to meet the SAAMI spec at the case mouth. In the case of 9mm, that's .380, maybe down to .377.


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Smiles,
 

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I had a similar experience with cast 147’s tumbling when using fast powders. The bullet caster recommended using slow powders. Switching from Green Dot to Blue Dot did the trick. Don’t understand but it worked. Powder type was the only change, velocities were same.
 

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Reloading 9mm and bullets that tumble....

I experienced some 9mm .356" moly coated bullets that tumbled and keyholed on the target when shooting at 10 yards or further.

I finally figured out the problem was the Dillon powder funnel I was using in my Dillon powder measure. The Dillon powder funnel also acts as an expander for the mouth of the case, and can be adjusted how far down he expander funnel expands the case from the case mouth. The powder funnel I was using had a diameter of .350" before it would flare the case mouth. It would shoot .355" JHP and FMJ bullets without issue, but when seating the softer moly coated lead bullets, it was most likely swaging the bullet to a more narrow diameter.....the bullet was not getting a good grip on the lands and grooves when fired, and the rounds would tumble/keyhole. I found an old .38super expander funnel that measured .353" and when it expands the upper portion of the tapered 9mm case, it does not swage the bullet excessively, so no more keyholing or tumbling with moly coated lead bullets..... I only use moly coated lead bullets for IDPA practice.... :)
 

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I've seen this on several S/A 9mm 1911's. The culprit is an oversized bore in the barrel. Easy fix is to shoot .357 to 358 dia bullets. When you load them, the brass will have a slight bulge. Ignore the bulge. You'll be fine. You are basically shooting 38 caliber bullets . This normally will stop the tumbling. Jp
 

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9mm bullets and tumbling

Easy fix is to shoot .357 to 358 dia bullets.
Not all 9mm barrels will allow oversized bullets to chamber, some chambers are tighter than others. The best option is to slug the barrel of a gun to determine the groove diameter. Modern 9mm semi auto guns should have a barrel with a.355" bore, so using .355" jacketed bullets should allow good accuracy. If the bore of a 9mm barrel is well over .355" bigger diameter bullets will help to prevent tumbling IF they will chamber.....
 

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I experienced some 9mm .356" moly coated bullets that tumbled and keyholed on the target when shooting at 10 yards or further.

I finally figured out the problem was the Dillon powder funnel I was using in my Dillon powder measure. The Dillon powder funnel also acts as an expander for the mouth of the case, and can be adjusted how far down he expander funnel expands the case from the case mouth. The powder funnel I was using had a diameter of .350" before it would flare the case mouth. It would shoot .355" JHP and FMJ bullets without issue, but when seating the softer moly coated lead bullets, it was most likely swaging the bullet to a more narrow diameter.....the bullet was not getting a good grip on the lands and grooves when fired, and the rounds would tumble/keyhole. I found an old .38super expander funnel that measured .353" and when it expands the upper portion of the tapered 9mm case, it does not swage the bullet excessively, so no more keyholing or tumbling with moly coated lead bullets..... I only use moly coated lead bullets for IDPA practice.... :)
I realize this was four months ago, but this suggestion needs to be supported. I had some 147gr lead flat-nose that I cast myself that were being swaged down too much in the 9mm cases when I used the Dillon powder funnel intended for 9mm. It was just too narrow. I switched to using the "D" powder funnel intended for my .357 Magnum rounds and it eliminated the bullet swaging problem. Only problem was with the reduced case height the powder funnel wasn't tall enough to engage the powder measure inside the powder throw, but around 11/64" worth of washers stacked on top of the powder funnel inside the mechanism fixed that. This really helped these rounds out a lot. As I recall, the symptom I was trying to eliminate was also keyholing, and that went away.
 
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