Thumbing bullets hits on paper

[brytec]

Hello, so I was at a local weekend match shooting my AKAI 38super comp that I recently acquired and second match shooting it...

Guys in my squad noticed my hits on the paper were not standard holes.. They were tumbled bullet hits ...same result from the first match I shot last Thursday ...I'm loading thru Dillon 650xl with 125g zero bullets lead exposed at the bottom, Winchester auto comp 7.5g & 7.8g, Winchester spp, starline 38super comp brass, PF 168-172... Would you be able to tell me what caused the bullets to tumble?

Thanks

Bryan

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[grantwoodok]

Aggressive crimping or soft bullets usually cause tumbling in an open gun. Try Montana Gold and you won't try anything else.

[czbeardly]

I tried some TC bullets that a friend uses... Extreme keyholing in my targets.. if they even hit... at 15 yards... They just didn't work :<

[Sarge]

ZERO bullets are very good bullets. When my open gun tumbled bullets it's because they were touching the comp on the way through

[wgj3]

I would echo what Sarge said. Those should be plenty good enough bullets.

Tp Sarge's 2nd point, look at the bore of your comp and see if you notice any smudges of copper that match the jacket color of the bullets. Use a good light and look all around the bore on each baffle of the comp as best you can. If you see copper, your gun needs work.

Another check would be to get someone else to give you a few of their rounds to see if they fly correctly out of your gun.

[tyler2you]

I had the same problem with the comp barely kissing the bullet and causing tumbling. Weird thing was there weren't any marks on the comp, but I removed it and the tumbling went away.

[lcs]

You say "you acquired" I am guessing the gun is used? Did you acquire it from the first owner? If the gun has not been tampered with--Call AKAI. Well call them anyway.

There is normally only 3 reasons for tumbling (1) Heavy bullet moving to slow (2) Over crimping (3) Bullets hitting comp because of comp.. I think you can rule out #1, pull a bullet from a loaded round. Over crimp will be visible. #3. Bullet hitting comp and the comp was not center aligned or it is loose. If #3 is the answer, you need t send gun to AKAI.

[grantwoodok]

I was shooting a 147Gr Blue Bullet .355 (hitech coating) over 5.4 Gr of HiSkor 700x getting 172PF and very acceptable groups. NEVER had a tumble.

I wanted to change to a platted or jacked bullet as I was tired of the blue stuff on my hands so I tried Berry's thick platted and Xtreme platted both in 147gr. Both sized .355 - Both of these tumbled. So my thinking was the comp must be fine as I'd shot the Blue Bullets with 0 issues, so it had to be the crimp. I worked the crimp back to the point where there was 0 visible crimp on the bullet. Still tumbled.

Then I tried a MG 147 CMJ and a 124 RN over the same load and had 0 issues.

[lcs]

I was shooting a 147Gr Blue Bullet .355 (hitech coating) over 5.4 Gr of HiSkor 700x getting 172PF and very acceptable groups. NEVER had a tumble.

I wanted to change to a platted or jacked bullet as I was tired of the blue stuff on my hands so I tried Berry's thick platted and Xtreme platted both in 147gr. Both sized .355 - Both of these tumbled. So my thinking was the comp must be fine as I'd shot the Blue Bullets with 0 issues, so it had to be the crimp. I worked the crimp back to the point where there was 0 visible crimp on the bullet. Still tumbled.

Then I tried a MG 147 CMJ and a 124 RN over the same load and had 0 issues.

That is the 4th reason......I missed it. The barrel just doesn't like the bullet. It happens.

[CHA-LEE]

You are using good quality bullets. My money is on the bullets hitting the comp as they are exiting the barrel and this is causing them to tumble. As others have already said, inspect the comp for evidence of bullet to comp contact.

[Aircooled6racer]

Hello: I would also look in the barrel on the top part to see if the grooves are worn out. Also check to see if the comp is loose on the barrel. Thanks, Eric

[BeerBaron]

Most often when I see guys with tumbling bullets it's too much crimp or an oal the gun doesn't like. What's your oal for that load?

Bullets striking a baffle in the comp is another good possibility as mentioned.

Sometimes a particular powder/bullet combo just seems to produce tumbling in a particular gun so changing part of the recipe may rule that out.

[jim v]

Slug your barrel (with pure lead slugs) and then use lead bullets that are 1.5 - 2 thou larger.

I use 0.358 lead bullets in my trubors and have zero problems.

[pskys2]

Also check the expansion chambers to see if there is lead buildup. Open based bullets will still build up lead in the chambers. If it builds up enough it can cause tumbling. One reason why JHP's and Complete Metal Jackets are popular. Plus the forming process of JHP's lends itself to less voids within the jacket at the base and why they always are a shade more accurate.

If you do see marks of the bullet touching any of the comps restrictor plates it may mean the comp is cracked somewhere, usually where the comp body meets the barrel cone.

But first clean the comp expansion chambers, load some ammo with just enough taper crimp to remove the flare and shoot 100 rounds. If the tumbling stops and groups are concentric with no flyers stretching the group out you will have isolated the issue to one of those two items.

Then load some rounds with a taper crimp of no less than .378.

Edited April 24, 2016 by pskys2

[troupe]

EGW sells a great reamer that will clean up the carbon and clear the bullets. Hope it is as simple as bullet crimp for you. My bullets measured with the crimp at .381 and shoot very well.

[brytec]

Most often when I see guys with tumbling bullets it's too much crimp or an oal the gun doesn't like. What's your oal for that load?

Bullets striking a baffle in the comp is another good possibility as mentioned.

Sometimes a particular powder/bullet combo just seems to produce tumbling in a particular gun so changing part of the recipe may rule that out.

OAL 1.240

[brytec]

EGW sells a great reamer that will clean up the carbon and clear the bullets. Hope it is as simple as bullet crimp for you. My bullets measured with the crimp at .381 and shoot very well.

With the crimp it measures as .384

[brytec]

You say "you acquired" I am guessing the gun is used? Did you acquire it from the first owner? If the gun has not been tampered with--Call AKAI. Well call them anyway.

There is normally only 3 reasons for tumbling (1) Heavy bullet moving to slow (2) Over crimping (3) Bullets hitting comp because of comp.. I think you can rule out #1, pull a bullet from a loaded round. Over crimp will be visible. #3. Bullet hitting comp and the comp was not center aligned or it is loose. If #3 is the answer, you need t send gun to AKAI.

I'm the third owner ... Previous owner did say he was using 124 MG

[bradsteimel]

I have heard where a small burr at the muzzle end of the barrel will cause tumbling. But if you have a comp, i can't imagine how a burr could just appear there (unless you've had the comp off). One way to know if it's your ammo, like someone above said, try someone else's ammo to see if theirs tumbles. If theirs tumbles, it's your gun.

[Chillywig]

Which zero bullets are you using? .355 or .356 The zero 38 super bullets are a little skinny. My zero 121 for 38 super measure .3555 or less. I do not have any to measure but think the MG are closer to the .356

[Sarge]

Which zero bullets are you using? .355 or .356 The zero 38 super bullets are a little skinny. My zero 121 for 38 super measure .3555 or less. I do not have any to measure but think the MG are closer to the .356

i rarely mic a MG bullet that's over .355. Last time I did a test run most were right at .3545

[Chillywig]

Are the 356 MGs undersized about like the Zero 356ers at ~.3555?

http://montanagoldbullet.com/index.php/9mm-130gr-super-fmj-183.html