What lead bullet diameter for 38super

I have a Kart 38 super barrel on the way for a 9mm 1911 that going to get swapped out.  I’m looking at Brazos 150g lswc and not sure what diameter to order.  .356, or .357,or .358?  I believe my barrel is a .355 1x16.

I would stay with .356. 

Thanks Len!

I believe Brazos will sell you a “sample” of each bullet diameter so you can determine the best diameter.  User “Lightfoot” is connected with the Brazos company and he can advise further.  It is my guess that .356 ot .357 will be best but there are two considerations, first there’s accuracy, but the second is will a .357 bullet chamber and function in my gun with my brass?  You can test that by loading a 38 cal REVOLVER bullet at .357 in a 9mm case and see if it will chamber.  I have a 44-40 lever rifle that will NOT accept ammo with bullets of .429 or .430 even though the groove is .429.

Interesting, I hadn’t thought about using a 38 revolver bullet to try that. I have some for my K14.

Your new Kart barrel will need finish reamed. Depending on the reamer used will dictate to some degree what bullets you can use based on the free bore and lead angle of the chamber. You might wait until the barrel is fit and finish reamed and try sample bullets before purchasing a bunch of them.
Jon

Thank you Jon!

Along with what Jon said, I would slug the barrel and find out what the ID is on the bore.  Kart's tend to be all over the place.