question about grain weight

[racky]

hey guys. i tried searching but couldn't find what i was looking for. so here's my question: if i'm loading, say a 115g 9mm, does it matter if it's HP or FMJ? shouldn't the powder load be the same since it's the same weight? thanks.

[r08ert209cali]

not necessarily things like bearing surface and overall length come into play. You should only use published load data. or very carefully work up a load. Post what you are looking for specifically and someone hear will have the correct data for you.

[J-cat]

JHP is loaded to a shorter overall length and requires a different, often lesser, powder charge.

[JC Smith]

I have Sierra and Hornady reloading manuals and they typically publish the same loads for bullets of equal weight regardless of the bullet type. Take the 115gr. 9mm for example. They recommend an accuracy load of 5.6gr. of Unique for both their 115 JHP and 115 FMJ (for a velocity of 1200 fps and energy of 368 ft. lbs.). They do the same thing for their .45ACP 185gr. FMJ and FPJ bullets, and many others. Obviously these are for the same brand bullet. Each manufatureres bullet is a little different and it's always best to use the reloading data from the manufacturer of your particular bullet. If that's not available then start with a mild load and work up. You never want to start out with a maximum load, even when working with published data for your praticular bullet.

[racky]

If that's not available then start with a mild load and work up. You never want to start out with a maximum load, even when working with published data for your praticular bullet.

that's what i was originally gonna do but trial and error can get expensive . i got some bulk lead rounds that don't have a brand name so i have to work from ground up to get the load right.

[JC Smith]

I can't be of much help with those. I've never loaded unjacketed 9mm and none of my manuals have load data for them. You might try some of the online load databases. I can tell you that in my Hornady manal, for .38 Spcl, they have a reduced powder charge for their 158gr. lead vs. 158gr, JHP. For example Bullseye: 3.6 vs. 4.1, Red Dot: 3.9 vs. 4.3 and Unique: 4.8 vs. 5.3 (those are maximum charges with the lower value being the charge weight for the lead bullets, and remember this is for .38 Spcl, not 9mm). The velocities work out to be about the same values. Now for .357 Magnum they list completely different powders for the jacketed bullets vs. the lead. For jacketed bullets they list heavier charges of slower powders and get higher velocities. I suspect they are assuming the reloader wants more performance out of the magnum jacketed bullet loads and perhaps also wants to keep the velocity of the lead slugs lower to reduce barrel leading.

[racky]

yeah i'm pretty much prepared to have a few accidental squibs and +P ammo trying to get the load right. i just don't wanna waste my primers. they're hard to come by now a days.

[JC Smith]

yeah i'm pretty much prepared to have a few accidental squibs and +P ammo trying to get the load right. i just don't wanna waste my primers. they're hard to come by now a days.

Yeh, me too with the small pistol. Wideners has Wolf primers in stock but the one they don't have is small pistol... they do have small pistol magnum, however, and everything elas.

[r08ert209cali]

when loading lead you need to stay around 8-900 fps anything over 1000fps can cause severe leading of the barrel. try using tite group powder if you can find it it works pretty good with light loads. take a look on reloadersnest.com

[CSACANNONEER]

that's what i was originally gonna do but trial and error can get expensive . i got some bulk lead rounds that don't have a brand name so i have to work from ground up to get the load right.

So, working up a load is expensive? I think it's cheaper than blowing up a gun, your hands and your face. Right?

BTW, r08ert209cali has it right! Even two different FMJs, JHPs or hardcast bullets of the same weight need different loads behind them. Everything from bearing surfaces to altitude to how deep they are seated in the case come into play. The seating depth issue is really an issue of how much room is left in the case once the bullet is seated. Normally, the less airspace, the quicker pressure will build up. There are exceptions to this though. Sometimes, severely undercharged ammo produces excessive pressure. I am not a rocket scientist and I can not explain why this happens. Well, even the rocket scientists and nuclear physicists who I shoot don't have a definitive answer for why this happens. Anyway, just remember to ALWAYS start out at the low end of the recommended powder charge and work up from there! Please, do this every time you change bullets, primers and even powders from different lots! Be safe and quit looking for short cuts. They can be very expensive and/or painful!

[Fjold]

If you start at the recommended starting load in your reloading manual you can interchange loads among bullets that are made of the same material (Jacketed vs Lead) JHP, FMJ etc are interchangeable at those levels and you can work your way up to the desired performance levels.

Oh, and JHPs are longer (not shorter) with more bearing surface than FMJ bullets of similar weight and shape. Because of the hollow cavity the manufacturer has to make the bullet longer to get it to the same weight as the FMJ bullets. (air weighs less than lead)

Loads with large air spaces in them (usually larger rifle cases loaded with small charges of faster powder) can experience a "detonation effect" which can result in very high pressures produced very quickly. Many of the old Nitro Express cartridges when loaded with smokeless powder instead of the old stick cordite, are charged with powder and then the case is filled with a small amount of puff dacron filler to reduce the air space to prevent this.