Average bore size on a .40 S&W pistol?

[Gunslinger]

I have ordered a EAA Witness in .40 S&W to use for IPSC Limited Division. I also bought a Lee 6-cav, 175gn TC mold that I will be casting with. Now, I want to get started making boolits for it before it arrives but I have no experience with this caliber. I want to get a die from Lathesmith for my Star, as I am very happy with his other dies. Only question is, what size should I get?

Best thing to do would be to wait for the gun to arrive and then slug the barrel. But from my experience if you are loading for e.g. a 9mm gun, then .357 works 99% of the time and the same can be said about .358 in .38 revolvers. What is the "lucky number" in a .40 S&W? I am thinking .401, but I could be wrong??

If there are any EAA owner with .40 S&W barrels that know their size I will gladly hear from them.

[ihuntbear]

I have ordered a EAA Witness in .40 S&W to use for IPSC Limited Division. I also bought a Lee 6-cav, 175gn TC mold that I will be casting with. Now, I want to get started making boolits for it before it arrives but I have no experience with this caliber. I want to get a die from Lathesmith for my Star, as I am very happy with his other dies. Only question is, what size should I get?

Best thing to do would be to wait for the gun to arrive and then slug the barrel. But from my experience if you are loading for e.g. a 9mm gun, then .357 works 99% of the time and the same can be said about .358 in .38 revolvers. What is the "lucky number" in a .40 S&W? I am thinking .401, but I could be wrong??

If there are any EAA owner with .40 S&W barrels that know their size I will gladly hear from them.

I wouldn't buy a mould without measuring your bore first .most guns shoot better having a 001 to .002 larger boolet

[Dusty Bannister]

Might first learn the difference between "bore" and "groove". Next, there is no reason you can not get started casting a supply of bullets and having them on hand to lube and size. Then when you find out what your barrel dimensions really are, you can tell Chris what they are and he can tell you what you will need. Then you will also know what your bullets are "as cast", just in case there is a problem with the mold. You will probably be a lot closer to successful fit than taking a poll as you seem to be doing. Dies are not particularly cheap, and this will keep you from getting a box full of dies looking for what will work. Take your time and spend your money once. Good luck. Dusty

[KYCaster]

.401 should work well.

Jerry

[popper]

40s do vary but chamber & throat do also. 0.401 is a good place to start.

[MT Gianni]

It will involve a custom sizer die if it is bigger than 0.401".

[DeanWinchester]

My mold falls .402. Using Federal cases and running through my (modified) Lee factory crimp die, a pulled boolit measures .401-.4015. I have no need to size them. I get zero leading.

Before the factory crimp die flaming starts, I use a wooden dowel and diamond lapping compound to lap,the carbide ring open about a half thousandth and I use ONLY the brand brass that I have checked many times. If you feel it touching the case (other than the belled mouth) that can be a bad thing.

Everyone else is right though, .401 is a great place to start but you really need to slug that bore before you get too involved. Nothing worse than a beautiful pile of boolits that are undersized.

[Gunslinger]

Might first learn the difference between "bore" and "groove". Next, there is no reason you can not get started casting a supply of bullets and having them on hand to lube and size. Then when you find out what your barrel dimensions really are, you can tell Chris what they are and he can tell you what you will need. Then you will also know what your bullets are "as cast", just in case there is a problem with the mold. You will probably be a lot closer to successful fit than taking a poll as you seem to be doing. Dies are not particularly cheap, and this will keep you from getting a box full of dies looking for what will work. Take your time and spend your money once. Good luck. Dusty

Well the mold casts as it casts, I can't do nothing about that. In my 5 years of casting I've used the same Lee 120gr TC booli sized to .357 in 5 9mm guns without problems. I've used the same .358 boolits in 6 revolvers also without issues. And it seems .401 is the lucky number when it comes to .40 S&W. The Lee mold is .401 according to specs.

[Oreo]

Well, the mold drops whatever it does but if it drops too small you've got a problem. There are solutions other then buying a new mold.

.401 might do but if you're taking a stab in the dark I'd go with .402. It won't hurt and will give extra margin for a larger throat / groove diameter. You never know if you'll pick up another gun in the future that the extra girth may be helpful in.

[Dusty Bannister]

My Glock factory barrel shoots well with the .401, and shoots just as well with .4015. But sized and lubed at .4015, there is NO leading. Your gun and your choice. Good luck. Dusty

[xr650]

My SIG and XD slugged at 401"

[Iron Mike Golf]

Two Beretta Model 96 Centurions (mine and my son's) slugged .402. Also had poorly reamed throats.

[rsrocket1]

Even if you slugged your barrel and found it was .402", you will have a hard time finding a mold specifically do drop exactly 402 bullets. Most are not that tight in tolerance. You can beagle the mold or open the mold up with the "bullet and abrasive" method.

Better to have a mold that drops at .402 or .403 and size down to the proper diameter. It's easier to open up a sizer than open up 6 cavities.

[popper]

I have the 2x Lee mould - works fine in both my 40s. Unless they messed up you are good to go.

[leeggen]

My PX4 slugged at .4015 and my mold droppped at .4025-.403 sized to .4025 and all is well. good luck and some good advise on here. Some say the 40 cal can be tempermental at times. I read alot on here before even starting. Short trial and error period then all was good.
CD