Rare Tumble?

[drivenagain]

147grRN BB 3.4grTG CCI 1.09 OAL

Shadow 2

Tanfo Limited

My buddy and I shot our very first loads in a match. Were were blown away at how accurate and soft the rounds were.  We made about 200 rounds and all shot flawlessly, except for about 4 total rounds.  Only out of my Tanfoglio Limited, I had 4 total rounds that had a slight tumble, 2 in practice and 2 in last nights match.  I was going to lower our powder but worried about the bullet not stabilizing.  Any feedback?

[RAP]

A couple things come to mind based off the information given. A) Those 4 bullets were not cast properly (defective) such as undersized or incomplete cast. I cast my own bullets and have experienced both. B ) Your bullet weight is not ideal for the rifling twist rate and velocity you are shooting them at for your handgun. I shoot a CZ P09 with 147 grain flat point NLG coated bullet with 3.3 grains of Sport Pistol powder at a muzzle velocity of 925 FPS. I have not experienced any issues with rifling twist rate but have had problems when I inadvertently under sized the bullets once and if I miss a bad cast and they usually don't shoot very well either.

[HesedTech]

Had the same problem so let me ask you this, are you using the Lee FCD?

 

In my Tanfoglio BB 147 would only plunk at 1.08 which caused almost all CBC brass to bulge. I tried to use Lee FCD to “fix” that issue but it swaged the bullets too small and caused tumbling. 

 

The fix was to sort out all CBC brass and use the normal crimp. 

 

The best fix was to switch to a different bullet profile that loads longer. ACME 147 FP, Extreme RN and PD FMJRN all worked great at about 1.14. I settled on PD which run perfect, accurate and are far easier to load. No problems with CBC brass and that saves huge amount of time sorting them out. 

 

I use the Dillon 9 mm dies on my 650. 

 

Note, I load for my son’s Shadow 2 and SP 01 and the issues are exactly the same. 

Edited February 17, 2018 by HesedTech

[drivenagain]

@RAP @HesedTech

Thanks for your replies.

I am using a Dillon 1050, loads shoot with no issues out of a PO-7, Shadow 2 and a SP 01, only those 4 out of my Tanfoglio.  I have 250 Flat Nose left that I was able to plunk/tight spin at 1.11 which surprised me, but they are snug Im not gonna lie.  I may try those today, or look for a different manufacturer.

 

[223to45]

I had that happen at a match, I was told I had too much crimp. It was stripping the plating off causing it to tumble.

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[Rjracing]

I’ve been told a tumble can need the OAL is too long, too short or too much crimp if the actual projectile isn’t at fault. 1.09 is a bit shorter than most people custom load 147gr that Ive seen, I prefer my similar loads around 1.15

[SlvrDragon50]

I don't think you're going to see a 1.15 OAL round in a CZ unless it's been reamed.

 

I load my 147gr ACME FP at 1.12 which past plunk test easily. If you can't fix the bullet issue, give the ACME a shot. I've tried a lot of their bullets, but the 147gr FP work great and load relatively long.

[HesedTech]

On 2/17/2018 at 1:09 PM, 223to45 said:

 

I had that happen at a match, I was told I had too much crimp. It was stripping the plating off causing it to tumble.

 

 

Any damage to the base area of a bullet is what causes bad aerodynamics and tumbling bullets. I, even with FMJ, crimp to close the bell gap on the brass. The way to test is load a couple and then remove the bullet. If there are any compression rings left on bullet because of the crimp, then yes it is crimped too much. 

 

But, the Lee FCD can make the coated or plated bullet too small and as it enters the rifling it essentially is not straight and deforms the bullet. Result is a bullet that tumbles aerodynamically. 

[muncie21]

On 2/16/2018 at 9:27 PM, drivenagain said:

147grRN BB 3.4grTG CCI 1.09 OAL

Shadow 2

Tanfo Limited

My buddy and I shot our very first loads in a match. Were were blown away at how accurate and soft the rounds were.  We made about 200 rounds and all shot flawlessly, except for about 4 total rounds.  Only out of my Tanfoglio Limited, I had 4 total rounds that had a slight tumble, 2 in practice and 2 in last nights match.  I was going to lower our powder but worried about the bullet not stabilizing.  Any feedback?

Aside from chrono'ing the loads, it sounds like you guys are on the right track; reloading and enjoying the fruits of your labor!!