I am working up a new load with my M&P 40. I went out yesterday and shot some paper and realized some, not all, of my bullets are tumbling/keyholing (not sure if those are the same term or two different terms - my bullets holes are not round but rather oblong). I shot about 200 rounds and I noticed probably 10 of them were tumbling/keyholing. Looking for ideas on what could be causing this. My components are as follows:

Powder: 5.1 grains Vihtavuori N320
Bullet: 180 grain xtreme RNFP plated
Seated: 1.137"
Velocity: 918 FPS
Crimp: .421" (10 bullet average) - ranges from .420-.422"
Bras: Mixed
Primer: CCI 500

When I was setting up my crimp I pulled a few bullets and the casemouth left just a slight indentation around the plating but did not break the surface.

I've never had this happen to me before. Any input, ideas, suggestions...

Clean the barrel very well shoot again if it still happens try some factory.

If it still keyhole send it back to S@W

Is that a roll crimp or taper crimp ? Should be taper.
Have you looked at a fired bullet ? Soft or hard lead ? Lead and plating deposits in barrel ?

These are plated cast bullets. Take a look at the bullets' bases. If the bases are not square and are "shaved" on one side (it happens...), they will not fly true.

Every instance of tumbling I've experienced was due to under size bullets.

Every instance of tumbling I have had was with an oversize, worn or corroded bore or a bullet too long or the twist was too slow or the velocity was too low.

Stop using the Lee factory crimp die. If in fact your using one? It may size the bullet in the case.

do not use a roll crimp on plated bullets. the plating is so thin that frequently the crimp causes the case mouth to cut through the plating

quote:

Originally posted by 243winxb:
Stop using the Lee factory crimp die. If in fact your using one? It may size the bullet in the case.

You are correct, I am using the Lee FCD. Most of the people I know around my local shooting circles swear by it. Sound like you have not had much luck? Are you suggesting the die may actually change the diameter of the bullet when you state "size the bullet in the case"?

I use lee dies in for all my handgun reloading never had this issue with them.

At this time I load for around 10 different hand gun calibers.

NEVER crimp an auto pistol round. You should make the bell straight again, and very lightly taper crimp if it makes you feel better, but thousands of rounds of 9mm and 45 ammo over the past 40 years of NOT crimping at all seems to work for me. You can do a lot of damage to a bullet by heavy "factory" crimping and heavy taper crimp. You can make the bullets too small so they gas cut and tumble to the target. I am amazed by how well the die companies have brainwashed new reloaders with "inventions" which are solutions to non existent problems.

Yes, and using to much taper crimp with some dies, may size the bullet also. Plated bullets are very soft lead. photos of plated bullets

quote:

Originally posted by DPollard:

quote:

Originally posted by 243winxb:
Stop using the Lee factory crimp die. If in fact your using one? It may size the bullet in the case.

You are correct, I am using the Lee FCD. Most of the people I know around my local shooting circles swear by it. Sound like you have not had much luck? Are you suggesting the die may actually change the diameter of the bullet when you state "size the bullet in the case"?

Like dcpd, I never crimp any of my auto rounds. Sounds like we have about the same years of experience. The only time I have had a tumbling issue is with undersized bullets,like some of the others. Try a magazine full without crimping and see what happens.

Jerry

Don't think I responded previously.
First, pull some rounds and inspect and measure the bullet diameter. Are the bullet 0.355" before seating and are they the same OD after seating? Is there a "crimp ring" around the bullet?
It is rare for a jacketed bullet to tumble, but all too common for plated.
I have only ever had a problem with the Lee FCD when using cast lead bullets that were about 0.003" over nominal groove diameter (though they were only 0.002" over actual groove diameter). In general, I see no problem with them, but they are mostly used because the reloader is seating bullets crooked and needs to "iron out" the bulge. Thus, they produce a great crimp, but too many times they allow the reloader to ignore a problem.

Yes, many hand loaders have "good" results with Lee factory crimp dies. However, for auto pistol ammo, they contribute absolutely nothing to the equation and often are the cause of problems. Hence my admonition not to use them. They are solutions to non-existent problems.

A few years back I had a 416 bbl on a new build that the bullets key-holed on.
Upon inspection I found that a mic'ed 416 cal bullet would drop down the muzzle 1-2".
The bbl maker quickly replaced the bbl and smith charges on their dime.

I measured my bullets and they are all .400". I will try to crimp without the LFCD and see if that solves the problem.

Did you pull any bullets and measure them? It is the bullet size after loading that 'may' be the problem.
Did you slug your barrel? What exactly is the groove diameter?
Have you tried a jacketed bullet?
The Lee FCD is NOT going to swage down a 0.400" bullet unless it has a manufacturing problem.