tumbling 9mm

[bentnbroken]

can anyone give me an idea where to start trouble shooting my 9mm loads are tumbling, not everyone ..... but still ? I load 124gr Berry copper jacketed, win spp and 4.0 gr N320 ... is tumbling caused by velocity issue ? or crimp, loose / tight ??? help

[thx1138x1]

what is your bullet size,what is your groove size?In general,I bet you have a problem there.Bullet not big enough,or you have a huge groove(bore).Oh you could be over crimping,squishing bullet under size.Load looks ok I"m running something real close to yours.

[Gryff]

Hard to say. My 147gr. competition loads are laser-accurate in my M&P and XD, but tumble when fired in a Glock 34.

[Pardini]

What gun? My cast boolits keyhole in my 9mm XDm. Have to size them to .358 to stop it.

[bentnbroken]

What gun? My cast boolits keyhole in my 9mm XDm. Have to size them to .358 to stop it.

Glock 34.... I guess I will go out and crono a batch see if any keyhole... check velocity and pull some bullets and weigh charge as well.

[Whiterabbit]

I've experienced and fixed lots of tumbling in pistols. Here's my experience:

#1 cause is bullet, #2 is powder choice.

For #1, it could be one of two things: the bullet diameter is too small, so it's stripping out on the rifling or doing "something" that makes its rotation no good. you can check this by inspecting a fired bullet, or by slugging your bore to see what the diameter is. At the muzzle should be good enough to figure out where you are at.

Other one is the bullet is wrong for the twist. This is probably not your problem. This is more of an issue for revolvers, which have many different barrel lengths and twist options compared to semi autos which tend to be properly designed for common factory ammo which does not have alot of variance (which I believe is the case for you)

#2 is wrong powder. I won't even speculate as to why this can affect you, but if this is your root cause, the only solution is to switch powders.

[bentnbroken]

Mr Whiterabbit thank you for the info. looking at door #2 may be a valid reason, I don't remember having this issue before using the n320...its the only variable as I have always used the same bullets and primers and have made no changes to crimp or overall length.........

[mjmagee67]

Too much crimp striping off the copper plating? Berry's have a pretty thin plating on their standard bullets. IMHO

[kcheung2]

I've used 4.0 grains of N320 with 124 grain plated Extreme projectiles without issue. It's a soft load but reliable. I don't think the powder was the issue.

[Whiterabbit]

Mr Whiterabbit thank you for the info. looking at door #2 may be a valid reason, I don't remember having this issue before using the n320...its the only variable as I have always used the same bullets and primers and have made no changes to crimp or overall length.........

I'd strongly suggest looking at powder only after measuring the bullet. IMO a thought experiment (in this case) is not enough to refute the idea that the bullet might not be a good fit for the gun.

Only data I would throw away is the idea that they work well in other firearms. That wouldn't affect any consideration I had for this particular one. Everything else is fair game.

After via measurement you validate the bullet is numerically right for the job, That's when I'd try a new powder.

Unless you like troubleshooting by loading and shooting, powder and primers are cheap . Just can't expect a perfect solution out of the gate without measuring the bullet.

[rsrocket1]

First of all, your "tumbling bullets" are all over the target right? Are you shooting with a cardboard backing or is the target a paper hanging without a backing? Sometimes a straight through hole looks like a keyhole because it rips the paper in an out of round hole.

Secondly, you really ought to know how to slug your barrel using pure lead sinkers. It's just like driving out a squib load with a range rod except you lube the barrel before hand so the lead slug will be easy to drive through.

Even if the option is #2, you are probably in a marginal condition with your other loads that "do not tumble".

Fit is king.