Big Guy Posted March 21, 2010 Share Posted March 21, 2010 (edited) Other than the bullets hitting the comp, is there other reason for bullets to tumble? Crimp? Too much, too little? Out of every ten rnds that I fire, two or three are tumbling. Checked the comp and saw no hits. Edited March 21, 2010 by Big Guy Link to comment Share on other sites More sharing options...
JThompson Posted March 21, 2010 Share Posted March 21, 2010 (edited) Other than the bullets hitting the comp, is there other reason for bullets to tumble? Crimp? Too much, too little? Out of every ten rnds that I fire, two or three are tumbling. Checked the comp and saw no hits. Detail? Bullet type? Load/powder OAL brass? Gun? To much crimp can cause it... Edited March 21, 2010 by JThompson Link to comment Share on other sites More sharing options...
Big Guy Posted March 21, 2010 Author Share Posted March 21, 2010 (edited) Other than the bullets hitting the comp, is there other reason for bullets to tumble? Crimp? Too much, too little? Out of every ten rnds that I fire, two or three are tumbling. Checked the comp and saw no hits. Detail? Bullet type? Load/powder OAL brass? Gun? To much crimp can cause it... Bullet: MG 124 CMJ Load: 7.9 g. IMR 7625 LOA: 1.22 Gun: .355 KKM barrel w/ Millenium Comp. Edited March 21, 2010 by Big Guy Link to comment Share on other sites More sharing options...
GentlemanJim Posted March 21, 2010 Share Posted March 21, 2010 Other than the bullets hitting the comp, is there other reason for bullets to tumble? Crimp? Too much, too little? Out of every ten rnds that I fire, two or three are tumbling. Checked the comp and saw no hits. Detail? Bullet type? Load/powder OAL brass? Gun? To much crimp can cause it... Bullet: MG 124 CMJ Load: 7.9 g. IMR 7625 LOA: 1.22 Gun: .355 KKM barrel w/ Millenium Comp. I have seen and owned a number of guns that tumble bullets. The one thing all had in common....KKM barrels Try a .356 bullet it may fix the problem Jim Link to comment Share on other sites More sharing options...
racegun9 Posted March 21, 2010 Share Posted March 21, 2010 Other than the bullets hitting the comp, is there other reason for bullets to tumble? Crimp? Too much, too little? Out of every ten rnds that I fire, two or three are tumbling. Checked the comp and saw no hits. I've seen it with some of the 1-32 slow twist barrels. Not sure if yours is a 1-32 or 1-16. Might try a zero bullet or a .356 like Jim suggested and see what happens. Link to comment Share on other sites More sharing options...
JThompson Posted March 21, 2010 Share Posted March 21, 2010 Before you go changing bullets etc, try just knock the bell off when crimping. JT Link to comment Share on other sites More sharing options...
Big Guy Posted March 23, 2010 Author Share Posted March 23, 2010 (edited) Just got back from the range after trying out different loads. Curiously, none of the 9mm (.355) MG 115s JHP that I shot today were observed to tumble. I had previous tumbling issues with the MG 9mm 124 CMJ (round nose). If there any scientific reason why the .355 round nose bullets will tumble and the .355 JHP bullets will not? Edited March 23, 2010 by Big Guy Link to comment Share on other sites More sharing options...
quade Posted March 24, 2010 Share Posted March 24, 2010 I feel your pain!! i've had the same problem. since i can't find zero's anywhere i bought the big box of MG .355 124gn HP's.i don't really think they are tumbling but they look like they rip through the paper. shooting from 166 to 175 power factor. been trying to figure out what's going on ever since. i even have 1500 rds.of the same bullet loaded by someone else from a totally different batch that do the same thing. its not every one just every 8 or 10th one. i just went through 200 Hornady XTP's 124gn HP with no issues. ????? Link to comment Share on other sites More sharing options...
Big Guy Posted March 24, 2010 Author Share Posted March 24, 2010 I feel your pain!! i've had the same problem. since i can't find zero's anywhere i bought the big box of MG .355 124gn HP's.i don't really think they are tumbling but they look like they rip through the paper. shooting from 166 to 175 power factor. been trying to figure out what's going on ever since. i even have 1500 rds.of the same bullet loaded by someone else from a totally different batch that do the same thing. its not every one just every 8 or 10th one. i just went through 200 Hornady XTP's 124gn HP with no issues. ????? What barrel are you shooting? Link to comment Share on other sites More sharing options...
Guy Neill Posted March 24, 2010 Share Posted March 24, 2010 The longer the bullet, the more it needs to be spun at a given velocity to stabilize. FMJs are longer than JHPs - but it does depend on velocity as well. Faster reduces the amount of spin needed for a given length. Of course, the spin is imparted by the rifling twist rate. Guy Link to comment Share on other sites More sharing options...
diehli Posted March 24, 2010 Share Posted March 24, 2010 FMJs are longer than JHPs Wait... what? That doesn't make sense. For the same bullet weight and diameter, because of the HP void, JHPs should be longer than FMJs. Link to comment Share on other sites More sharing options...
Aircooled6racer Posted March 24, 2010 Share Posted March 24, 2010 Hello: Measure the diameter of the bullets you are using. What is the twist rate of your barrel 1:32 or 1:16? The 1:32 works better for lighter bullets like the 115's. Thanks, Eric Link to comment Share on other sites More sharing options...
Big Guy Posted March 24, 2010 Author Share Posted March 24, 2010 Hello: Measure the diameter of the bullets you are using. What is the twist rate of your barrel 1:32 or 1:16? The 1:32 works better for lighter bullets like the 115's. Thanks, Eric Just talked to the people at KKM and they confirmed that the 1:32 twist barrel was designed for the ligther bullets. Link to comment Share on other sites More sharing options...
usmc1974 Posted March 24, 2010 Share Posted March 24, 2010 I had that happen in a glock with rainier plated bullets. Turns out I was over crimping then I turned down the crimp (alot) and it went away. Link to comment Share on other sites More sharing options...
Pezco Posted March 24, 2010 Share Posted March 24, 2010 I would go with JT advice first. I had the same issue and resolved it by changing my crimp (increased). Link to comment Share on other sites More sharing options...
quade Posted March 25, 2010 Share Posted March 25, 2010 I feel your pain!! i've had the same problem. since i can't find zero's anywhere i bought the big box of MG .355 124gn HP's.i don't really think they are tumbling but they look like they rip through the paper. shooting from 166 to 175 power factor. been trying to figure out what's going on ever since. i even have 1500 rds.of the same bullet loaded by someone else from a totally different batch that do the same thing. its not every one just every 8 or 10th one. i just went through 200 Hornady XTP's 124gn HP with no issues. ????? What barrel are you shooting? i've got a KKM, maybe 6K rds through it. Link to comment Share on other sites More sharing options...
VegasOPM Posted March 25, 2010 Share Posted March 25, 2010 My Open gun will "keyhole" (or tumble) if the bullets are heavier than 125 grains. Link to comment Share on other sites More sharing options...
Neil E. Posted March 25, 2010 Share Posted March 25, 2010 Just got back from the range after trying out different loads. Curiously, none of the 9mm (.355) MG 115s JHP that I shot today were observed to tumble. I had previous tumbling issues with the MG 9mm 124 CMJ (round nose). If there any “scientific” reason why the .355 round nose bullets will tumble and the .355 JHP bullets will not? The theory is that a JHP has more weight at the base. This stabilized the bullet in flight. CMJ (round nose) has very little weight difference form nose to base, allowing any slight unbalance to cause tumbling Link to comment Share on other sites More sharing options...
revomodel10 Posted March 25, 2010 Share Posted March 25, 2010 (edited) if you wonder about twist: http://www.schuemann.com/store/tabid/78/s-39-twist-rate.aspx LISTEN TO THE MAN, HE MAKES BARRELS..... Also how long have you had this problem? your comp ports may not be open or true enough for your bullets to clear.........LOOKING FOR CLUES IN THE COMP MAY NOT SHOW THE PROBLEM GOOD LUCK WITH YOUR PROBLEM Edited March 25, 2010 by revomodel10 Link to comment Share on other sites More sharing options...
Big Guy Posted March 26, 2010 Author Share Posted March 26, 2010 So for IPSC, is there an ideal twist rate? How much, if any, will the twist rate affect recoil? I guess, the shorter twist the more torque. Is this how it works? Link to comment Share on other sites More sharing options...
diehli Posted March 26, 2010 Share Posted March 26, 2010 So for IPSC, is there an ideal twist rate? How much, if any, will the twist rate affect recoil? I guess, the shorter twist the more torque. Is this how it works? http://www.schuemann.com/LinkClick.aspx?fileticket=N0S0LsAu1RQ%3d&tabid=67&mid=445 That being put out there, 1:16 seems to work for most folks shooting 124/5s. Link to comment Share on other sites More sharing options...
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