40 S&W Numbers

[philthephlier]

My Beretta 96G that I believe has seen only Jacketed bullets before I bought it used has these bore dimensions: .4035" groove to groove, and .390" land to land, which yields .0065" rifling depth. A new Lee 175 gr TL SWC mold casts 14.3 BHN alloy at
.4035" to .4045". Should these boolits be sized? If not, what size custom spud should be made to properly prepare the cases so they will be nice to the boolits when seated? Then how to set up the seating die to taper crimp without deforming?
I hope I'm asking the right questions. My learning curve for the 40 S&W is at the very beginning. Would be great if geargnasher could weigh in on this as he is bringing me up to speed. Thanks in advance for all replies.

[Cherokee]

Well, sounds like you could lube a few and try them - after you throughly clean all the copper fouling out of the barrel of that Beretta. I would suggest you bell the case mouth enough so the bullet will set on top, then seat without crimping. If you have a separate taper crimp die, use that. If not, back the seating die out some so it will not crimp, then seat the bullets, then readjust the die to apply the crimp, which should be just enough to remove the bell so the case is straight sided. Just my thoughts.

[geargnasher]

I'll offer what worked for me, my gun is dimentioned a little differently than yours.

My general approach, considering I've done just about everything wrong there is with this caliber, is to get the boolit at least .001" larger than groove diameter, and get about .001-2" of interference fit between the case and boolit. That means the expanded case should be about .002-4" smaller inside diameter than your boolit, which is sized .001" over bore diameter. Theoretically, you might need a boolit that's .4045 at least to prevent leading, but if you use a faster powder for this caliber (like Universal or Unique) and load it to pressure levels that are just over the elastic limit of your medium-strength alloy even groove-sized boolits might work and not gas-cut and build up lead in your barrel.

To get the tough, hard .40 brass to expand the right sizefor medium-to-soft boolits, sometimes I have to use a spud that is the same size as the boolits, because there is so much springback. With harder (20+bhn boolits) being fired fast (1100+fps) with slow powders (HS6, Longshot, Blue Dot, True Blue, etc.) more boolit tension is better, meaning a smaller expander, one about .002" smaller than boolit diameter. With 800-900 fps stuff powered by midrange charges of Universal and 12-15 bhn boolits, I find the spud needs to be about .001" smaller than the boolits or so to give the MOST tension and the LEAST boolit swaging. It's all a balance here, and no one-size-fits-all.

My principle concern is whether or not your chamber will accept a .4045" boolit loaded in the case. My M&P .40 wouldn't reliably chamber anything over .403". Considering it was designed for J-words which I found average about .3985", it's no wonder we have so much trouble with getting cast boolits to work with standard dies and chambers.

Check the case mouth ID of a fired case with any crimp removed and this will give you a clue as to how big your chamber is, and the limit of how fat of a boolit you can use.

Decide what your goals are for this gun performance-wise, and go from there. If you want full-house stuff, I found that I had to do things much differently than with lower-power "fun" loadings. You can treat this just like a .45 ACP if you want to make it easy, use faster powders, softer boolits, a big expander, and go for about 800 fps tops.

Again, the short version of what MY gun, brass and dies need, your experiences might differ substantially:

>Top end loads: Slow powders worked up to near or at maximum listed charges, .002-4" case tension, really good lube like 50/50 or carnauba red, BHN 20+ boolits about a thousandth or slightly less above groove diameter.
>Medium loads (900-1000 fps), medium powders like Universal or similar, 12-15 bhn boolits, .001-2" case tension, just about any lube, and about a thousandth over groove.
>Plinker loads (750-900 fps, just enough to cycle the slide) need fast powders like Titegroup, 231, Red Dot, Clays, anthing in that spectrum, boolits at least 8 bhn and the expander spud the same size as the boolits, which might need to be a thousandth or more over groove to work well.

You'll just have to try to get a good, basic fit of the boolit and then do some shooting to see how it works out, but making up your mind in advance about what level you intend to load will eliminate some hardship here and simplify the process.

Hope this helps,

Gear

[9.3X62AL]

That is a BIG groove diameter for a 40 S&W--bigger than any I've slugged. 40 barrels have been boringly consistent for me, never more than .4015" at throat or .401" in grooves. I'm talking a sample population of at least 30 barrels here.

The Lyman Multi-Expander spud I have is .398", and does well with W-W cases and .401" boolits in 92/6/2.

[prs]

I will say THANKS to Geargnasher too becasue I have been working with this boolit and loading today. In fact, I am in the house now becasue a storm just ran me in from casting the Lee tl401 -175-swc trying to apply some of gnasher's tips RE hot moulds. Great results, so far, but it is slowing me down waiting on boolits to freeze enough to drop without smearing. Alloy at abou 675F and mould at "about" 365F, but that is hard to measure with infra-red gun.

Earlier today I was measuring my boolits and cases and was wondering if I should get a larger internal powder through sizer for my Lee disc measure With my alloy and my mould and my technique (not Gear's, these I cast hot and frosty with very hot alloy) the boolits I cast a couple of weeks back were a tad over .401". Lucky me. I tumble lubed them with thinned LLA + JPW mix, let it cure and then sized to .401". Then relubed and let cure again. Today the boolits were between .4006" and .4008". As the cases came out of the Lee powder through die the internal diameter was .399". The finished product fit the chamber well and shot well (as far as my limited talent can tell - it rang cowboy steel every shot at 12 to 30 yards. I shot 100 rounds in my Glock 23 with OE barrel (old generation Glock) and the only thing the too saturated patches produced was powder residue after a bronze brush was used. I saw no lead particles of such.

I do not know the barrel diameter specs as poly grooves and lands have me a little puzzled RE how to, but air cooled 95% lead, 3% antimony, 2% tin as loaded above must have fit well even though is was a very mild charge for plinking (Trailboss).

Storm has passed, back to the shop.

prs

[geargnasher]

PRS, with that alloy you might try running it even cooler, right down to just above the point where the spout freezes. At around 625F with WW alloy that's out of the slush phase at 560F I can run most of my two-bangers at between three and four pours a minute for as long as I can stand it or until the pot needs refilling, whichever comes first. With the cooler alloy you can maintain the maximum casting pace while keeping the mould plenty hot enough for nice, satin boolits (light frost) because you are putting fewer BTUs into the mould blocks each pour. That's the way I do it, anyway. If you need more production, I think Lee makes that in a six-banger, then applying the same principles of hot mould/cool alloy you can make the boolits fall, as is often said here, "like rain".

As long as you're getting results that make you and your gun happy, keep it up!

Gear

[philthephlier]

I don't think Beretta wanted cast boolits shot in this gun. The groove diameter of .4035" sounded excessive to me so I checked and rechecked it and it is just that. Hard for me to imagine jacketed bullets at .400" could fill those grooves but the gun shoots the jacketed bullets beautifully and the high pressure cartridge that it is must be upsetting them enough. Question now is will a cast bullet under groove diameter which it will need to be for the cartridge to chamber do the same thing?
Doubtful in my mind. The mouth diameter of a fired case is right at groove diameter. Any thoughts?

[prs]

Thanks again, Gear. I do use the 6 cavity moulds. I usually run two of then at once, but I only have one of these for the 40. I run two 20# pots when doing that; deplete one, restock it and use the other while the first comes up to temp. I had some odd typo's that I fixed about the sizing; oops.

The storm cooled the outdoor temps from low 80's to upper 60's and that made a difference in cooling speed, very noticible. Anyway, I did drop the alloy temp a little, did not go as low as you have suggested here, will keep that in mind. Got about 50# of keepers and a well broken in 6 cavity mould. Also a sore back ;-)

prs

[noylj]

You're not at .40035 are you?
Now, let's go back to the good ol' days of milsurp 9x19 guns.
Back then, the standard milsurp 9mm barrel, and almost ALL factory barrels, had groove diameters of about 0.357-0.361", a 0.006" increase over the "nominal" 0.355" specification.
Back then, .357 jacketed bullets almost always performed better than .355 bullets (and were a LOT easier to find), though the .355 jacketed bullets still did better than lead.
"Thankfully," the chambers were generally generous enough that, if you could find them or make them, 0.359" lead bullets performed pretty well.
Never assume the manufacturer has the slightest idea of what dimension the barrel SHOULD have.
At least you slugged the barrel.
Finally, remember that your gun and barrel are individuals. You MAY have enough pressure with a soft enough bullet to be able to shoot 0.401-.403" bullets without issue. You need to test variables and determine what works for you.

[geargnasher]

I don't think Beretta wanted cast boolits shot in this gun. The groove diameter of .4035" sounded excessive to me so I checked and rechecked it and it is just that. Hard for me to imagine jacketed bullets at .400" could fill those grooves but the gun shoots the jacketed bullets beautifully and the high pressure cartridge that it is must be upsetting them enough. Question now is will a cast bullet under groove diameter which it will need to be for the cartridge to chamber do the same thing?
Doubtful in my mind. The mouth diameter of a fired case is right at groove diameter. Any thoughts?

Phil, I was afraid of that. I'd say your gun is fundamentally mis-dimensioned for cast boolits. Do not dispair, though, until you've tried it. You never know for sure until you put some lead down the pipe and see, it might surprise you.

Like Noylj mentioned, I'd hedge my bet by using a soft alloy for my boolits, like 50/50 stick on/clip-on weights mixed, and I'd also try some Clays or 231 to kick the base of the boolit in the pants to try to get it to "bump up" in diameter and seal (obturate) the bore as soon as it leaves the case, if you find the right pressure and rate of pressure build for the alloy, you might find something that works very well. Then again, you might not be able to get a boolit to bump up without skidding the rifling, but as deep as your grooves are, there is considerable hope for the soft boolit/fast powder thing. Give it a shot.

Gear

[shoez]

I just got the 6 cavity Lee in the TL 175 gr .401 mold a couple months ago. Mine drop between .401 and .402 from a less than scientific random sample when cast from ww's. Lubed and loaded them with 4.2 gr of 231 and shot them out of a new Ruger SR40. Zero problems. Same accuracy as factory. Some light leading after 200 rounds, but brushed right out. When buying a .40, as this is my first .40, I looked at the Beretta, but didn't like the unsupported chamber. Watch out for bulges!