I am getting ready to load some 38 Special ammo for my backup pistol, a S&W Airweight. It is +P rated, but I was planning to load standsrd loads in ordwer to conserve materials. After reading recomdations agains loading light using heavier weight bullets (140gr or more), I've decided that I'll load at the high end for a standard load, not +P.

On to my question... I am using 158gr FMJ FP bullets that are .358 diameter. I only have two reloading manuals (Hodgdon 27 and Speer 13), and both of them refer to a .357 diameter for the 158 grain bullets. One shows a .358" for the 160 grain. I understand that the manuals are illustrating their exact test conditions for how they achieved their results, but is their any known problem for using a .358 in a 158gr weight? I am assuming I can load it pretty much the same that they loaded their .357 diameter bullets?

Any info or recommendations would be appreciated.

No difference at all. Work up as normal until you find accuracy.

Great... thanks for the info.

I shoot 158 gr .357" XTP in a .355" groove .380 with more powder [8.5 gr Power Pistol] than a max load 357 mag [8 gr Power Pistol]. There is no pressure spike, it is well behaved. As long at the bullet gets a running start, it will swage down to a smaller diameter, and not affect the powder burn pressure peak.

Holy Smokes! I load 8.5gr of Power Pistol in my 357 Sig rounds... but in 380 I'm only using 4.2gr of Power Pistol. Jeepers!

I can't fit 8.5 gr Power Pistol behind 158 gr in 380 at .984" , but I have a 100 year old 380 with a mag that will take 1.090" OAL.