subsonic load data frustration

[Thegeek]

Everywhere you turn you hear if you want 9mm subsonic, you need t use 147gr bullets. Call Mach1 1125fps. There's a lot of recipes for projectiles as light as 115gr showing velocities under 1000fps. I've spent the best part of the last 2 hours looking for 147gr projectile options and load data for the various projectiles I've found. I like the Berry's offering because they're cheaper and have great reviews.

I still can't get over the fact that you are always told not to deviate from the load data. So how the hell are all these bullet companies sold out of bullets when I can't find any load data for them? It's crazy. Based on what I'm running now (Remington 115gr FMJ, 4.2gr titegroup) I should be in the 1100 fps range already. There's a lot of information printed about sectional density and whatnot, so why don't bullet manufacturer's publish this information? All it means for the rest of us is give it best guess where the safe level is, and if your gun survives, start looking for pressure signs.

Here's the rub. Titegroup is a pretty narrow window anyway, and 147gr lead has a range of 2.5 to 2.8 grains. My powder measure throws +.1/-.1 range. Not much margin there. Along those lines, the 2.8gr maximum (which they say never exceed) produces a C.U.P. of 30,300. Further down the table, 700x has a C.U.P. of 32,200. I know burn rate and several other factors play in, but almost 2000 difference just seems odd.

 

[ryknoll3]

I don't know what we're supposed to do with this.....

My only response is that you don't need load data for every specific bullet you're using. You use data from similar weight and construction. If you have a cast lead bullet in 158 gr., it doesn't matter who's cast bullet. If you have a jacketed bullet in 115 gr., it doesn't matter who's bullet you're using. If you're using plated, the standard wisdom is to use cast bullet data, though Rainier says start with middle-range jacketed info, and Berry's says either hard cast data or middle-range jacketed. It's not really more complicated than that.

As to powder, that's why you work up. Work up from starting (except with certain plated, who's mfg's recommend middle-range for starting weight) and work towards max load until you're satisfied with function, accuracy and velocity. Oh, and .1 of a grain over max isn't going to blow up your gun if you worked up your loads and didn't see pressure signs building. So, if you work up that Titegroup load that you mentioned and you didn't see any pressure signs at 2.6 and 2.7 and you decide to go with the max of 2.8, a .1 overthrow by your powder measure isn't going to cause a problem. Just work up your loads for YOUR gun carefully.