Red_Dog_Leader said:
Although their website doesn't say what kind of coating they use, I think IbejiHeads bullets look like "Hi-Tek" type coating and Bayou Bullets who uses Hi-Tek coating recommends that we use lead load data -
http://ibejiheads.com/product_info.php?cPath=1&products_id=29
Also, IbejiHeads 9mm bullets come sized either .356" or .357" so they will likely produce higher velocities than .355" sized bullets (as in higher chamber pressures).
Picture above shows bejiHeads 128 gr RN. It's got "non-step" nose which means the nose is less pointed than the typical "stepped" nose RN and will result in longer bullet base than 125 gr RN.
If you look at the comparison picture above, you will notice Missouri 124 gr RN (non-step) has shorter nose and longer bullet base than Dardas/Z-Cast RN (stepped) bullets. Instead of typical 1.125" OAL/COL I use with stepped RN, with non-step bullets, I need to use shorter 1.080" - 1.100" to prevent bullet's bearing surface (part that rides the rifling) from hitting the start of rifling. So use the OAL/COL that will allow the dummy round (no powder/no primer) to fall into the chamber freely with a "plonk" and spin without rubbing the rifling but also function test the dummy round by feeding it from the magazine and releasing the slide without riding it to ensure reliable feeding/chambering - this is your final "working OAL/COL" you use to conduct your powder work up.
Due to longer bullet base, using shorter OAL/COL also means the bullet base will get seated substantially deeper and raise chamber pressures.
If you look at the comparison picture below, the Missouri non-step RN loaded at 1.080" compared to FMJ at 1.135" shows different OAL/COL due to different shape of the bullet nose but notice the curvature of the bullet (ogive) just above the case mouth that will engage the rifling are about the same.
Now I know if I use the sierra load data to back down start charge for shorter COL (and also the Ibeji being a coated bullet), but was wondering how much.
Start at the min load, min load -5%, -1/2 grain less than min load?
How do you all approach this?
125 GR. LCN W231/HP-38 Diameter .356" OAL/COL 1.125" Start 3.9 gr (1,009 fps) 25,700 CUP - Max 4.4 gr (1,086 fps) 31,200 CUP
Due to deeper bullet seating depth, when I used Hodgdon's lead load data with 124 gr Missouri "non-step" lead RN at 1.080"-1.100" at 4.2-4.4 gr, I got full-length leading in my .355"-.356" groove diameter Lone Wolf barrels (the higher chamber pressures from deeper seated bullet base were over-driving the bullets). When I reduced my powder charges to 3.6-3.8 gr, my leading stopped and I ended up using 3.8-4.0 gr without leading.
So for your 128 gr coated "non-step" bullet (which will have even longer bullet base than 125 gr non-step RN), I would use lead load data and reduce the start/max charges by .2-.3 gr.