i am thinking that I shall cast my own bullets since i have an unlimited supply of cheap lead. any problems with straight lead bullets in my S&W SD40? any recommendations before i buy a bullet mold?

i have been casting for over 30 years and only use wheelweights, i cast a lot of different calibers and 40 is one, i use a lee double cavity mold that drops a 175 grain bullet. works great.

Lead bullets work fine in all of my guns ie 4006,646,sigma and my convertible ruger 38/40-40 s&w. I use the old lyman ideal design
for the 38/40 Winchester cast from straight wheel weight metal or
sometimes linotype all lubed with 50/50 alox lube. I have no feeding
problems or leading issues. Many leading issues can be avoided by
using flat-based designs.

flat-based designs.????? SWC?

Flat-based (bottom of bullet) as opposed to bevel based.

do I need a gas check?

Gas checks are not usually necessary, if you size your bullets at least .001 over the groove diameter of your barrel.

Take a soft, lead slug (or bullet) and push it through your barrel, so that the grooves are engraved onto the slug. Then, take your caliper and measure the diameter from the groove on one side to the groove on the other. If it measures .358, for example, size to .359 and lube. The bullet will upset to completely fill the bore when fired, thereby preventing any hot gases blowing by the bullet and melting a little lead into your barrel.

If all you have is pure lead, the bullets may not fill out. You can buy alloy with lead and then determine a mix to give you about 1% tin for flowability.
Most cast bullets are cast much harder than required. You need the bullets to be at least 0.001" larger than the groove diameter of you barrel and you can usually go up to 0.004" with great results.
Once upon a time (late '70s/early '80s), I cast and then lubed and sized by bullets. Then, I decided to try them as-cast. For this, I melted some stick lube and pan lubed my bullets. This gave me slightly better accuracy and more consistent accuracy.
Then Lee came out with Liquid Alox and I have been tumble lubing ever since.
I am still a firm believer that, for me, the RCBS/Lyman type lubrisizers are more likely to damage a bullet. If I had to size bullets, I would go with Lee's kit or get a Star sizer.
I would get steel SEACO, RCBS, or Lyman molds, and 3 or 4 cavities, if available. I would get a 20lb bottom pour pot and think that the Lee is so inexpensive that you can go through one a year and probably still be ahead of spending $300 for an RCBS or Lyman.
I am prejudiced in favor of 155-175gn L-SWCs in .40 and 10mm. If not SWC, the truncate-cone or flat-nose bullets.
Lee's aluminum molds are inexpensive and can produce some great bullets, but they are delicate (can be damaged easily) and require some changes in casting technique (you need to keep the lead 50-100 degrees F hotter and you need to cast fast or keep heating the mold in the lead melt as aluminum has a low heat content so it heats and cools very fast).
If you look at Lee, get the 6 cavity. Aluminum is light and they produce a lot of bullets quickly.
Get Lyman's Cast Bullet manual and read it before you do anything else.

Hi

This is the Lyman #401043 bullet, originally designed for the 38-40 WCF cartridge.



It is casted hard and weighs 170grs. It has a ojive/profile very similar to a lot of jacketed bullets.
This one has worked out very well in my .40 and I've not had a single problem with it. So well, that I've not tried any other design.
Here is a small sample of loads I've experimented with it, along with a jacketed load I shot;




Seems to like Unique the best.
Notice how much better the handloads shoot compared with this particular factory load..

Hope this helps a bit.

wow, thats awesome, you have saved me a ton of guess work
I cant say enough how much I appreciate this site and the people on it!

thanks again!
Scott

I use the same bullet, same Unique load, magic in my 4006 (1 1/2" @ 50ft). Sim load of WSF also shoots well. The 40 can be a challenge to get good lead bullet perofomance out of. It is a high pressure round, so unless you cast them on the hard side, they "skid" & accuracy suffers as well as you get leading, regardless of proper fit. I have good luck w/ this design from air cooled ww & siezed 0.401" using whielabel CR or BAC or Magma lube.

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