.40 S&W 175 grain lead with 231

I've been using 231 with 180 grain MG CMJ and been happy. I finally decided to get a mold for .40 and got a Lyman 4 cavity 175 grain TC beveled base. (I already had a Lyman Handle and have been happy with the other Lyman molds I have.)

I'm sizing them to .401 and actual weight is 176 grains.
I loaded up 10 with 4.5 grains of 231 and chronographed them yesterday at an average of 895 FPS. That's a little faster than I need for a range load. I'm looking for about 830FPS.
I can't find any loading charts for lead with 231 in the books that I have and am wondering how low I can go powder charge wise.

Thanks bobo06

Welcome to The Guide.

Just use your 180gr jacketed data. There's no real difference between cast and jacketed loads in most pistol cases, and the 5gr difference is too small to matter. It's only when you get into big magnum revolver loads that it begins to become an issue, and not always even then. In any event, it's generally safe to use data for a slightly heavier bullet than your data was generated for, but not for a lighter one. A cast bullet weight for weight will have lower pressure and higher MV than jacketed.

I have never had much luck with any BB moulds or commercially cast BB bullets. They tend to gas cut excessively as the most important part of the bullet to obturate into the barrel grooves (the bullet's base skirt) is missing. As in all cast bullets, undersized and too hard an alloy make the problem much worse. If you aren't happy with your results, I would suggest instead either the Lee TL401-175-SWC or 401-175-TC in 6cav version, depending on what kind of sizer you have. Either will work with tumble lube and push-through sizing, but if you have a conventional nose first sizer then you have to go with the 175TC.

Whatever mould you end up with, .401 is way too small. That is what is available commercially. You are casting them yourself to avoid the problems inherent in commercial cast bullets, aren't you? If you push it too hard it will lead up your barrel very quickly. Slug your bore and go with at minimum .002" over groove. Measure the slug with a mic, not a caliper. Even a digital caliper with four decimal readout is only accurate to .01 =/- .005" no matter what its display reads.

Keep your alloy as soft as you can, 1:3 or 1:4, WW to pure.

I am assuming you are not loading for a Glock with a factory barrel. If you are, the rules are completely different for the their polygonal rifling and you need the hardest alloy you can find for safety, but size is still critical.

It's for a Sig P226 and P229.
I've got over 1,000 lbs. of ingots from wheel weights that I've had for about 12 years that I'm using.
From the Winchester guide I have, 200 Grain lead is 3.0 to 4.0 and for a 170 Grain lead it's 4.0 to 5.2 of 231. I'm going to back the charge down to 4.2 and chrono 10 of them.

I haven't slugged either barrel but i will do that this weekend.


Thanks for your suggestions

i'd just back down the powder charge a titch and see what happens.
if you don't got problems and the 40 is doing fine i'd just shoot the thing.
your's has gotta be the first post i have ever read where everything was good right out of the gate with a 40.
you might lose the obduration you have now with the slower load, if you see leading start i'd just go back towards the original load.

In handguns with cast bullets, load data for jacketed bullets will work with cast bullets of basically the same weight. So if "X" gr. of .231 gived you 830 FPS, the same charge with a cast bullet will be faster. I'm thinking your drop to 4.2 gr. will put you very close to the velocity you're looking for.
Paul B.