Reloading guide mismatch

[omega42]

I have a box of Berry's bullets (9mm 115 gr. RN) with a recommended overall length 1.130. Powder is Hodgdon CFE Pistol which recommends overall length 1.100 for 115 gr. LRN. Their only other data is for SPR GDHP which I'll try another time. Source on both is the manufacturer's websites. Short of making a big variety of test loads, which is the better bet?

 

[EddieCoyle]

Use the OAL from the bullet company.

 

[asp]

Jim's right. Reason being is that, for a given bullet, OAL affects 2 things: internal case capacity and feeding. Change the shape of the bullet and both change- but the bullet mfg knows this and that's why they publish their own data.

Keep in mind that all bullets with the same overall shape (round nose, truncated cone, SWC, etc) are not created equal. The round nose on one might have a slightly different profile than the RN on another causing more of the 115 gr of mass to be outside the case, causing a mismatch on internal case capacity, OAL adjusted to make it all play nice.

Hope that helps give some reasoning as to why Jim is right. Because he's always right.

 

[omega42]

Good to know, thanks.

Range results: I went with the Berry's OAL and it took the Hodgdon LRN max charge weight (5.4 gn) to cycle reliably. No chrono data because I haven't bought one yet.