Moving a 9mm recipe from 115gr to 124?

I loaded with almost the same load and oal you're using but with 124 FMJ. The plated rounds might need a skosh less.

Win 124 FMJ, 4.30gr Win 231, 1.111" 1065-132PF "Chrony", CZ75B
This may not be the best choice for your load, more oal may feed or shoot better in your gun.

When the PF goes down to around 130 Win 231/HP38 gets pretty 'sooty' in my gun. It wipes off, but coats everything black fast.

I've been told Tightgroup is cleaner than HP38/Win231, but still a little dirty. I'm using Vit n320 and it shoots cleaner at low PFs. I've read solo 1000 does too.
All these seem to be commonly used by competitors, but so are WSF, Bullseye, Unique, 700 and others.

Always check published load data when changing bullet weight. According to Hodgdon's data you will be over the maximum load of 4.4 grs with a 125gr lead bullet but under the 4.8gr maximum for a jacketed bullet. For the Berry's plated bullet you should be OK kind of splitting the difference but note that for both these loads the pressure is the same even though the charge weight is different. Note the difference in pressure between the lead bullet and the jacketed with different powder charges.

When I load a 124/125gr bullet in the 9mm I use 4.0gr W231/HP-38 for a lead bullet and 4.4gr W231/HP-38 for a jacketed bullet. I use a OAL of 1.125" with the lead bullet and an OAL of 1.100" for the jacketed bullet. The above Hodgdon listing verifies what I've been doing and it works out well for me...

Lucky, If the Berrys bullets that you are using are the plated ones , there is likely no reason that you could not extend the OAL to as much as 1.145-1.150 if you so desired and keep the same load unless you are already at or near maximum charge. With my 9mm Ruger P-95 I still have 0.065 free gap to engage the riflings with a 125 grain 2R-RN bullet.

The plated bullets are more like lead than jacketed and the free gap is not required and could improve accuracy shorten it. Not really related to pistols but, a lot of bench shooters actually breach seat their bullets by intentionally leaving the OAL in excess so that the rifling engagement seats the bullet back when the bolt is closed.

Take with a grain of salt cause pistols are not rifles and visa versa.

You will have a slightly reduced case capacity if you keep the same COAL. It could raise the pressures a little.

I like Berry's 124gr plated RN at 1.150" with 4.3gr Win231. For competition I like to set the OAL at 1.150 because the tolerance then is +/-.010" and they still work great. This is a nice long RN that feeds really well in my CZ.

You may not need to do all of the following, but the guy who taught me to reload must had OCD. For load testing, he had me keep all the variables the same and adjust only one component aspect to test.

- Same brass headstamp weighed and sorted by similar weight
- Single stage sizing/deprime and hand priming with flash hole/primer pocket check
- Bullets weighed and sorted by similar weight
- Powder charge hand weighed on scale

For me now, I use mixed headstamp/don't sort case by weight but do single stage size and hand prime.

With any new box (1000) of bullets, I randomly weigh about 10 bullets for weight consistency. FYI, Montana Gold FMJ and Rainier Ballistics plated bullets have less than 1 gr variance between bullets. If your bullet weights vary too much, just group similar weights together (within 1 grain) and keep them in different boxes (some shooters shave lead base off FMJ but you can't do this to plated bullets).

I hand weigh powder for load testing, but use press powder throw for match loads (charge to charge difference should be less than 1/10 grain).

For 9mm, I use 1.125" OAL and W231/HP38 (my designated match powder).

As to match accuracy, if I get 2" at 15 yards off hand/bag, it's good enough for me.

For practice, start with 8x11 copy paper side by side (one lower) and practice your double taps. Then move to 1/2 sheet side by side and then onto 1/4 sheet side by side.

If you get any flyers, find out which variable caused it and eliminate it. I do not get flyers on my match loads or practice loads.