9mm Coated Lead Bullet Experiment

[celem]

Today, I did a test using Lucky13 Green Zombie 9mm Coated Lead Bullets sized .357. I was using my Beretta 92A1 which has a large .3575 slugged bore that is prone to keyholes with undersized lead bullets. I reload lead bullets with a Lee Classic Turret press w/o FCD. The first position is a universal decapper and the remaining positions are a Lee 3-die 9mm set.

I loaded one batch of cartridges using the standard 9mm expander that came with the 9mm die set. I loaded a second batch with a 38S&W expander die.

The results of firing these two batches is interesting. Look at the attached photo. Same shooter (me), same distance (10-yards), same pistol (Beretta 92A1) same powder, primers, cases and bullets.

The left target is the batch loaded with the standard 9mm expander and the right target is the batch loaded with a 38S&W expander die. Quite a difference!!

 

[Tcruse]

Yes, a big difference. So, are you saying that the coating was being damaged when forced into the small neck (9mm Expander) as the reason for the difference?

 

[Schwing]

I don't have pictures of my targets (I do have the targets so I will try and remember to post them later) but I did a similar experiment over the weekend with my 92fs (which also has a .3575 barrel!) I feel your pain there. I actually have started using 125 grain .38 special bullets sized to .359.

In my experiment, I went from the 38S&W expander plug to the Lyman M die... the difference was astounding. I went from about 3" groups to about 3/4" groups. Back when I was using the 9mm expander, I was lucky to hit the paper.

So, are you saying that the coating was being damaged when forced into the small neck (9mm Expander) as the reason for the difference?

The difference is that, by not expanding the neck enough, the case actually swages the bullet down in size completely killing accuracy. You can test this by pulling a couple of bullets after seating and checking their diameter. If they are smaller than they were going in, you have not expanded the case enough.

 

[vaalpens]

Very interesting and informative post. Thanks!

Maybe this topic should be added to the THR Group Project - PISTOL - Advanced Reloading Concepts and Discussions thread.

 

[rsrocket1]

The 38 S&W acts like the Lyman "M" die in that it expands the case further down. Even though I size my 9mm bullets to 0.356" (tight M&P throats), the expander prevents swaging and allows for a much better fit even with 0.356" bullets.


You can see the "bulge" in the loaded cases. I use a separate taper crimp die to close the bell (not the Lee FCD which will swage the bullets and allow them to be pulled out with just finger pressure due to the slippery powder coating).

 

[Schwing]

First off, awesome bullets! I love powder coating!

The 38 S&W acts like the Lyman "M" die in that it expands the case further down.

I can't believe that I spent several years trying to find that elusive good accuracy in 9mm cast loads before I was directed to the 38 s&w expander plug. For most of my 9MMs, it was the ticket. For my 92FS, however, I have to size the bullets to .359. I found that it works really well until the bullets get above about .357 in diameter. After that, I was getting a lot of split necks trying to open them up wide enough. The M die seems to work a little better for that.

The one huge drawback to the M die is that it is not a powder through die so, if you are like me and have a 3 stage press, it adds some time to your process.

 

[HankC]

It is because shaving or swaging? Flaring with Lee Universal Flaring Die does the job as well?

 

[Jesse Heywood]

Can you put a mike to the expanders?

 

[celem]

Yes, a big difference. So, are you saying that the coating was being damaged when forced into the small neck (9mm Expander) as the reason for the difference?

I went through this in the past with my own Powder Coated cast bullets. The difference was that the lead would be swagged down. Pushing the .357 bullets into the case would basically size down the bullet, which defeated the point of sizing them to .357. The Powder Coat is extremely hard and was not being shaved when pushed into a belled case. The point of using the .38S&W expander is to prevent the swagging. This has been discussed a great deal on castboolits forum, where is where I picked up the tip of using a 38S&W expander to avoid the swagging problem. Accurate lead bullets must be sized larger than FMJ - .357 and even .358 if the lead is softer. Lucky13's bullets are hard enough for .357. When I case wheel weight lead I size to .358.

 

[GLOOB]

The left target is the batch loaded with the standard 9mm expander and the right target is the batch loaded with a 38S&W expander die. Quite a difference!!

And if you had ever tried this before powder coat, you might have never bothered with it. The difference between those targets is obvious. The difference in lead fouling is even more impressive. The powder coaters are learning all kinds of ways to reinvent the wheel!

If you have a 75+ yard berm, you don't even need paper to see the difference in accuracy. It will be obvious as night and day that the damaged bullets are not shooting straight by taking 4-5 shots at the berm.

This is the reason some folks have kindly suggested that powdercoating is sometimes a crutch and not a solution for fouling. Unless your bore has a constriction, if powder coat is fixing your fouling problem, there is a big chance that it is doing so by covering up a problem that is decreasing your accuracy.

Can you put a mike to the expanders?

I'm NOT the OP and I don't have a mic. But my Chinese made calipers show that my Lee standard expander is .353" and way too short to reach the base of the bullet. My Lee 38S&W plug is .356" and can just barely reach the base of an average 124 grain bullet. I have switched to an NOE powder thru plug that measure .356 with a .360 flare, and it's just about the same length as the Lee 38S&W expander, maybe a touch longer. No real difference, other than I like it for a little less flare on the case mouth. The Lee 38SW plug is really close to perfect for most 9mm cast bullets between .356 and .357. Works fine with my .356 MBC bullets (my calipers show these at .356 with one or maybe two spots that might measure .355 1/2) with no loss of neck tension.

I posted some finding on this in another thread. I determined that when seating my MBC bullets using the stock expander, the bullet still measured a full 356 all the way around the entire base except for one small spot that measured 354 1/2. But the difference in accuracy and lead fouling was profound.

Some calibers you might not need an oversize expander, particularly if your size die is loose. Due to the shape of 9mm cases, it appears it is fairly common for the dies to close up the necks a little too much, requiring an oversize expander. Rule of thumb, if your ammo has a visible coke-bottle, snake that swallowed a pig look to it after you seat a bullet, you may benefit from an oversize expander. An expander no more than 1 mil under the diameter of the bullet is my own preference, with under half a mil being even better. If you can't detect any bulge at the base of the bullet with your naked eye, you probably don't need it. If you put calipers on there and measure a sub 2 mil bulge, then an oversize expander mostly likely won't even affect your brass, at all. Your size die isn't sizing the brass small enough for it to even matter. Of course pulling bullets and measuring is the most definitive test; just be sure to measure all the way around the base of the bullet and to test in a variety of your thickest brass.

There is a sticky over at Cast Boolits with hundreds of posts regarding 9mm cast bullets and the use of oversize expanders. Also, if you're cheap, you can try using your Lee 357 expander. I'm not sure if it's quite as large as the 38SW in diameter, but it expands to the same depth, anyway. It will work in a 9mm die if you put a piece of dowel behind the plug.