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New/First instance of bullets tumbling


rowdyb
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All other previous gun, bullet, casing, primer, powder, whatever loads I've made have never tumbled. But now I am getting about one every 20-30 rounds or so, seen at targets as close as 7 yards and as far as 20 yards.

To narrow down the variables where I was before tumbling occured:

-same cz sp01 shadow

-ammo made by automatic accuracy. thousands of rounds no tumbling.

-ammo made by me. 147gr rnd nose xtreme, 3.20 titegroup, range brass, winchester spp, 1.120 oal, .377 crimp

-dillon super 1050. all stock dillon dies.

What has changed from the above to now having tumbling issues?

-addition of egw u-die

-new lot of xtreme bullets

What have I done? Remeasured my oal, swage, crimp, powder charge. All at my desired specs. Inspected the crown of the barrel and saw no dings, gouges or anything.

So if the only thing I've changed is to open a new box of bullets and to use a different sizing die, the egw U die would any of these variable changes cause tumbling??

My guesses are:

-new box/lot of bullets that is "off" and some just aren't getting a stablized concentric spin.

-U die is somehow effecting the bullet and causing the effect. Increase in pressure? Tearing of plating? Entering the rifle off? Undersizing the bullet as it seats?

But...... nothing I can think of from the U die would cause tumbling when all the other variable are the same. I have loaded up a box of U-die and a box of Dillon die now to shoot back to back as an experiment. And I do have some Precision Delta and Montana Gold bullets on the way in the same weight and profile to do the same experiment with.

What's the collective wisdom, opinion, guess? All I know is I've never had it before in tens of thousands of rounds done exactly the same. All I changed was adding the U die and opening the next box of bullets in the stack.........

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X-Treme makes two 9MM 147 Round Nose Sized to 356 and Sized to 357

Which one are you using?

X-Treme other 9MM are as follows

115 RN 355

115 HP 355

124 FP 355

124 RN 355

135 RNFP 356

165 RN 356

I am interest in your post because I have tumbling problems also.

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but when the bullet is seated, that should make the brass it is in the same, right? no matter what the sizing die used was? the crimp die doesn't care what is below the seated bullet...

not arguing, just going through my own reasoning and rationale so that i can learn in the process if i am wrong or misguided in my thinking.

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i guess i go back to, what makes a bullet tumble? grossly i'd say it is anything that keeps the bullet from becoming stabilized by the time it leaves the barrel. so that's why i checked

-crown of the barrel. looked good.

-rifling. everything looks even and consistent. also, only like 30k rounds on this barrel.

-powder charge is what i have written down it should be. did an average of 10 drops and it is what i have marked on the hopper.

-finished measurements like oal, crimp and such. all within the spec i like and proven in other's loads

-gross check of bullets to see if plating intact and not wildly away from measurement.

-yes, previous boxes were .357 as well.

I think I was able to eliminate the choice it might be the gun. Which leaves me with ammo. Either the components I am assembling the ammo from or the final product in the process of its assembly. But that's just my thinking. If I knew the answer I woulda fixed it ant not posted, hahahaha.

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Xtreme bullets seem to be made of a very soft alloy. When seating them I get nipples that I don't get on coated / cast bullets.

Using the U-Die you are under sizing the brass. The brass may be swaging down the soft alloy (at least the part in the case) preventing it from completely engaging the rifling. I would measure a couple bullets before seating and then pull them to see if the brass has staged the soft lead base of the bullet.

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when you pull a bullet do you see any marks on it? I've used over 45,000 Extremes (124s &147s) and at first I didn't have any tumbling but my group size seemed larger than it should have been. Someone here suggested I check my crimp and when I pulled bullets every one had a slight ring/mark at the crimp ...backed off the crimp until there were no more marks on the bullet & I was back to shooting 3" groups at 25 yds off hand all day ...

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I think a possible cause may be the bullet being swaged in seating or crimping. If you use range brass of varying headstamps, you might get one here and there, that the case walls are thicker than the rest. Thicker brass will resist the bullet being seated more, possibly swaging, and also taper crimping with the occasional thicker walled brass, may swage the bullet somewhat. I would first try an easy fix of backing off the crimp a little and see what happens. Depending on your bore diameter, and how close your bullets are to it, it may not take much swaging to cause tumbling issues.

If all your bullets tumbled, I would suggest pulling a bullet from a loaded round, and measuring it, but since the issue is at random, that might not be conclusive. It would not hurt to slug your barrel to get a bore size measurement. Some 9mm bores slug .357 or larger.

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Using the U-Die you are under sizing the brass. The brass may be swaging down the soft alloy (at least the part in the case) preventing it from completely engaging the rifling. I would measure a couple bullets before seating and then pull them to see if the brass has staged the soft lead base of the bullet.

This is my concern also, and recommend you try this.

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Good, will do! And yes when asked I do use mixed range brass as it's what I get for a good price, $0.

OK, U die back in. Measure base of bullet, seat it and crimp it, then pull bullet and measure again and look for signs of over crimping as well.

Though previously when pulling rounds due not priming or whatever all I've ever noticed was a slight indent, not breaking the plating, around maybe 1/4 the circumference of the bullet.

For the sake of example, if pre-seating the bullet measured .357 and after seating, crimping and being pulled it measures .355 is that bad? What is the threshold between good and bad? None? 0.001?

Will this matter if I switch from a plated to a jacketed bullet?

Thank you so far for the help.

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It might be a recent batch. I shot about 200 rounds on practice Saturday, and had 2 tumblers and a mike I suspected was a tumbler. I have loaded over 7000 Xtreme 147 RN, but the latest batch are in a new style box.

This is at 25 yards. I was chrono'ing at the same time and took the first two shots left of the target so it wouldn't hit it but to make sure the chrono was reading correctly. Then I took my 5 shots on target. I was surprised to see the 6th tumbler:

XSu9jWhl.jpg

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Mine are from a batch of 10,000 rounds I bought a few months ago. They are in the old style, larger box. That key hole looks very much like what I am seeing. I see it on close or far targets at about one every 20-30 rounds.

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When you do your testing separate the head stamps and see if it's one particular headstamp that tumbles. That will go a long way towards isolating problems such as crimp.

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Good, will do! And yes when asked I do use mixed range brass as it's what I get for a good price, $0.

OK, U die back in. Measure base of bullet, seat it and crimp it, then pull bullet and measure again and look for signs of over crimping as well.

Though previously when pulling rounds due not priming or whatever all I've ever noticed was a slight indent, not breaking the plating, around maybe 1/4 the circumference of the bullet.

For the sake of example, if pre-seating the bullet measured .357 and after seating, crimping and being pulled it measures .355 is that bad? What is the threshold between good and bad? None? 0.001?

Will this matter if I switch from a plated to a jacketed bullet?

Thank you so far for the help.

Any reduction in diameter is bad. Plated bullets are too soft and the plating too thin to stabilize at groove diameter. If you leave a mark on a plated bullet after taper crimping, any mark, this is too much crimp. If the bullet starts out at .357 and you pull it, it should still measure .357. If not you found your problem. If the U-Die is reducing the diameter then only the front of the bullet is engaging the rifling correctly. If taper crimping reduces the diameter then only a small portion of the rear of the bullet engages. Either way the bullet rattles down the barrel and does not spin enough to stabilize after it leaves the muzzle. An FCD that is a hair too small at the sizing ring will make you pull your hair out. The carbide ring on the 9mm version should not even touch the bullet as the 9mm is a tapered case. I am pretty sure you will find the problem after you have pulled a few loaded bullets.

Edited by bowenbuilt
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results!

  • pulling bullet from round made with dillon sizing die no swage/deform of bullet base. significant crimp ring full circumference.
  • pulling bullet from round made with U die, small deformity of bullet base and again significant crimp ring full circumference.

Both tumbled today in shooting. So I backed off crimp until no more mark on the bullet but would still case gauge and cycle in the gun manually. I also have some jacked bullets to try. At first check the new jacketed bullets did not show any bullet base deformity when pulled from a case from the U die. Nor with my new crimp setting was there any mark on the jacketed bullet.

So my shooting test experiment today will be:

  • new crimp setting, dillon die, plated bullet.
  • new crimp setting, U die, plated bullet.
  • new crimp setting, U die, jacketed bullet.
  • new crimp setting, dillon die, jacketed bullet.

All from a rest, all indoors, all same powder and primer, all same gun. Whichever one "wins" is my new load.

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Scientific Method! Isolate variables, test, refine, test, check. Just back from the indoor range.

Old crimp, dillon or U die, and bullets tumbled.

New crimp, no tumbling, either die. Crimp was just adjusted empirically. Adjusted till no marring of plated bullet and would also chamber check and case gauge 100% of the time.

Jacketed bullets shot smaller groups than plated bullets. Especially evident at 20 yard testing.

Result? Keeping the U-die from EGW. Keeping new crimp setting and being more vigilant about checking it. Switching from plated bullets to jacketed projectiles.

Thank you for teaching me the importance of crimp and how trusting a number I've used for years doesn't guarantee an outcome.

Edited by rowdyb
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Good, will do! And yes when asked I do use mixed range brass as it's what I get for a good price, $0.

OK, U die back in. Measure base of bullet, seat it and crimp it, then pull bullet and measure again and look for signs of over crimping as well.

Though previously when pulling rounds due not priming or whatever all I've ever noticed was a slight indent, not breaking the plating, around maybe 1/4 the circumference of the bullet.

For the sake of example, if pre-seating the bullet measured .357 and after seating, crimping and being pulled it measures .355 is that bad? What is the threshold between good and bad? None? 0.001?

Will this matter if I switch from a plated to a jacketed bullet?

Thank you so far for the help.

A good shooter I know says to run the crimp down till you have tumbling then back off the crimp die 60 degrees(a little less than a quarter turn) if you are using dillon dies.

He loads a great deal of very accurate ammo and obsesses over group size, consistency, etc.

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