Bullet undersized from case?

[Daryl]

Ok, one thing I've learned in loading is attention to details.

I'm working up a cast bullet load for 40 S&W. I've slugged three barrels and they range from .4015 to just under .402. So, I'd want my lead bullet to be at least .402 and I ordered a sizing die to go at .4025.

Now, I'm working with unsized bullets to get the dies & all adjusted. My as cast Lee 175 TC drops at about .403.

So, when creating a dummy round, of course it won't chamber right after seating. So, I am using the Lee factory crimp die (i.e for the taper crimp).

An empty sized case drops easily in and out of all three barrels.

It takes about 3/4 to 1 turn on the FCD for the round to drop in and headspace on the case mouth in all of the barrels. When this is done, I pull the bullet and it is at only .400! The about 1/32" of the forward driving band is not in the case and that chambers fine at .403.

Even at just 1/2 turn on the FCD, the round will only drop about 95% in the largest chamber. But, the pulled bullet still measures only .4015.

So, am I missing anything? It seems that if the case is sized to chamber, then the bullet is swaged down to below groove diameter and all the ability and benefit from sizing .001 over groove diameter is lost.

[462]

A typical result from using Lee's Carbide Factory Crimp Die. A conventional taper crimp die is what you need.

Some CFCD owners have removed the carbide sizing ring, which converts the die to a conventional taper crimp die.

[runfiverun]

how much room do you have in an unsized case?
does it chamber?
now you know you need a 402 sized boolit to fit your bbl.
the trick is getting that size to chamber, either with thinner brass, less sizing, or planning for the squeeze with a boolit that will not be squished. [harder alloy]
the other option is sizing less which of course won't chamber, you might need to have the chamber polished some.
those lee dies are designed to make jaxketed work and are going to make all your ammo to the same size.
so i'm thinking thinner brass
less sizing [polishing out the sizer die ring]
or bigger chamber.

[Daryl]

A typical result from using Lee's Carbide Factory Crimp Die. A conventional taper crimp die is what you need.

Some CFCD owners have removed the carbide sizing ring, which converts the die to a conventional taper crimp die.

462 - Thanks. Interesting. I assumed the FCD did the same basic thing as the taper crimp but sounds like not so. Is a typical chamber slightly tapered? - so that the case mouth might get more taper to fit and swage the bullet a bit but not all the way back? I may try removing the insert as well.

[462]

The problem is not with the crimp section, located at the top of the die, rather it's with the carbide ring, located on the bottom, which sizes the case to jacketed dimensions. Because your cast boolit is fatter than a jacketed bullet, as it enters the die the carbide ring swages it down.

If you remove the ring, you can seat using the seater die then crimp with the modified FCD.

[beerbeer95648]

I removed to carbide ring on all my FCD's. I had undersize issues with a .452 bullet that I narrowed down to this die. I put the die in a padded vice with a spare nut on the die to bottom out on the vise jaws. I then drove out the ring with a nut driver that just fit in the die from the top. The ring came out in one piece and could actually be replaced if needed.

[geargnasher]

Welcome to the unique hell of trying to shoot cast in a .40 S&W handgun.

I've loaded for Glock with aftermarket barrel and stock M&P, both have tapered chambers that won't accept properly expanded cases stuffed with .403" boolits. They both slug at .401" and will barely chamber .402", which works, but it requires exactly the right seating depth, boolit hardness, and taper crimp to function reliably.

As has been said, the dies (and chambers) are made for jacketed bullets in the .398-9" area, and this presents a problem with cast boolits. Most production chambers in other calibers have more than enough room for the extra few thousandths of diameter we typically need to use with cast boolits, but the .40 is really tight.

If you want to shoot cast in the gun and have it work well, you'll need to enlarge the chamber to give the clearance you need with the boolit diameter you need.

Gear

[44man]

Welcome to the unique hell of trying to shoot cast in a .40 S&W handgun.

I've loaded for Glock with aftermarket barrel and stock M&P, both have tapered chambers that won't accept properly expanded cases stuffed with .403" boolits. They both slug at .401" and will barely chamber .402", which works, but it requires exactly the right seating depth, boolit hardness, and taper crimp to function reliably.

As has been said, the dies (and chambers) are made for jacketed bullets in the .398-9" area, and this presents a problem with cast boolits. Most production chambers in other calibers have more than enough room for the extra few thousandths of diameter we typically need to use with cast boolits, but the .40 is really tight.

If you want to shoot cast in the gun and have it work well, you'll need to enlarge the chamber to give the clearance you need with the boolit diameter you need.

Gear
This is the answer!

[HeavyMetal]

This problem Can have lots of answers as outlined above.

Any or all of them could be an issue.

How would I handle this?

One thing at a time!

So first lets take the FCD die out of the loading cycle. Now lets make a dummy round with out the FCD die and no attempt to crimp it.

Pull the boolit and measure it. Is it under sized? If it is you have an expander plug to small for the boolit you loading. Have another plug made that's closer in size, but not larger than, you boolit diameter.

In this case if you loading .402 I would have an expander plug that "mike's" .400 to .4005.

Once this is done load and pull to make sure it's right. If it is now use the FCD die to just barely take out the flare of the case mouth. The problem with the taper crimp is everyone thinks they need to "see it" like a roll crimp. If you can see a taper crimp it is way to much crimp!

Now pull a boolit from a dummy round and measure it. If it's the same diameter as loaded you good if not adjust the die as suggested and try again.

Once you get a loaded round that isn't being "adjusted" by the spec's of the die set your using check chambering with some dummy rounds.


Now, knowing that your ammo is correct for what you want to do, you can adjust the chamber of your gun if it needs it!

[geargnasher]

Heavy Metal, a few things to add to what you said. First, if boolits are in the 12-13 bhn range (NOT the best in the .40 unless using really light, target loads or gas checked boolits) you will need to have the expander spud made to the same size as the boolit to prevent the boolit from being squeezed undersized. I've played with a lot of different headstamps in the .40 caliber and the brass is all so springy you can still have .0015" to .0020" case tension holding the boolit if your expander is boolit-sized.

Now, if using 20+ bhn boolits, which work much better IME in the .40, you can get away with an expander that is .001" or so UNDER boolit size, but the expander had better be long enough to expand the case at least .030" or so deeper than the depth to which the boolit base will be seated or the boolit base will be undersized.

The trick is getting a fat enough, hard enough boolit into a case, the loaded case in the chamber, and the boolit back out of the case and delivered into the rifling without screwing up the fit of the boolit. Actually that's the trick to ALL cast boolit work, but the .40 won't let you cheat ANY. Everything HAS to be right.

Gear

[btroj]

Just one more reason for me to not ever buy a 40?
I will stick to my 45 and my revolvers. So much easier.

[geargnasher]

I would tend to agree very much with that, Btroj, but sometimes it really is nice to have a 13+1 handgun that can lay down quite a hail of high-energy fire even with cast boolits. When things are right, I can shoot 2" groups at 25 yards at the speed of sound with 174-grain boolits and have about the same recoil as a medium .45 ACP. It CAN be done, but can be like when my FIL told be after I'd burned the first brick of primers in R&D with his .40, "You're taking all the fun out of this!".

Gear

[btroj]

I have desire to get a 40 but this makes it even more so. This seems like a lot of work to get a gun to run with cast. But in this day and age how may manufacturers care about shooting cast? The are guns made for shooting factory ammo and the gun companies sell to the masses, not us lead sniffing wackos.
A tapered chamber? Why? What a pain.

I did like the way you explained the expander size in relation to bullet hardness and cases springiness. You put it very clearly and it should be easy for anyone to understand. Bravo.

[HeavyMetal]

Gear you are correct. Harder boolits will make a difference in how much you can get away with in an expander plug diameter.

If his problem is in the die set than 20 BHN will certainly help him keep his fit where it needs to be but if he has a chamber problem 30 BHN won't help his feeding problem.

Which is why I suggested the round about route that I did because, for me at least, I want to know what the problem is and repair it.

[Daryl]

OK, I got a Lee and Redding taper crimp die today. The Redding seems like it will do he trick in the SW 4006. I can get it to taper crimp the case mouth to just drop in and headspace. When I pull the bullet, the base is still .4015+ - much better than what I had before. The Lee kind of worked but must have a much steeper taper because it really crushed the case mouth down before the rest of the round would chamber - it left the base over .401 but imbedded the case mouth into the bullet heavily.

Don't know when I'll get a chance to load and test. I agree with HeavyMetal that I probably need an expander plug when all is said and done. One step at a time, though.