Relatively new to reloading, especially 9mm: I recently received my 9mm RMR 124 gn TCFP match winners and 124 gn JHP wanted to run my thought process by those more experienced: I’m using Win231, have had great success with 4.3 gn behind Berry’s RNFB at 1.14” in CZ P01. Got the RMR’s behind good reviews on here and elsewhere and trying to create a similar nice target load. My manuals (Lee 2nd, Lyman 50th) don’t show much info on TCFP, so loaded ladder based on plated 124 gn at 3.9, 4.1, 4.3 gn . I go in 0.2 gn increments as my Lee powder scale throws 231 in 0.1 +/- 0.04 gn, so I don’t see the benefit in comparing e.g. 4.14 vs 4.16 and I’ll stop my ladder at 0.1-0.2 below max. the Lyman 50th shows 124 gn JHP of 3.8 -4.5 of 231 with COAL of 1.06”. Reading on forums, RMR JHP are needed to loaded pretty short in CZ’s shorty throats, but also have a pretty long ogive. Plunk test has TCFP at 1.09 COAL and JHP at 1.05” (which even then is just at the go range based on a few dummies). What concerns me is I started looking at my brass length 0.748” (untrimmed now once fired Win) and bullet lengths. Even though the TCFP is 0.05” less than the berrys, actual case capacity based on seating depth (as length) is only reduced by 0.012” compared to Berrys and a similar bearing surface so I feel pretty comfortable expecting similar results to the Berrys RN. The JHP however reduces the case capacity by 0.056” and has a longer bearing surface, both which lead me to think of higher pressure. On top of that, my brass seems to be 0.06” below the reloading books. My question is if I load my ladder at 3.9, 4.1, 4.3 for the JHP, could I potentially have a dangerous pressure spike at the 4.3 or even 4.1 given the RMR may have different dimensions than the test projectile in Lyman? I’ve read a 0.03” seating difference can greatly spike pressures and it seems that different manufactures could produce JHP’s at different lengths. I am using federal SP match primers and in theory know what to look for but I my knowledge have not experienced an over pressure load to date. I am ok with learning what overpressure looks like, I just don’t want to lose appendages or a gun while doing so. Thankyou.