Bullet Data & Reloading Manuals

[grant22]

Search turned up nothing for me. What do you do when you have a bullet that doesn't quite match up to the bullet data in a manual? Example:

Let's say I have a MO Bullet lead .380 acp in 95 gr. The closest thing in my Lyman manual is lead 90 gr.

How do you guys do this or where do you start? There IS a 95 gr FMJ bullet data in the manual (same weight but way different bullet) which I understand as apples and oranges.

Also, thru some comparing I've done, it seems that larger weights of similar bullets usually get a smaller load of like powder. Is this because it's like horsepower vs. torque? A 4 cyl vs. a V8?

I plan on reloading some .380 soon, and I do have the lead 95 gr but need to know where I should start with developing the load. Using Bullseye, Lyman says to start the 90 gr 2.4. If I'm doing a 95 gr, I'd assume I would start at about 2.2????

Thx

[BigBronco]

I have used the phone to call the powder manufacturer and ask their expert. I know Aliant was very helpful.

[cpatbay]

Some load data are available on manufacturer's (both powder and bullet) website but otherwise call them and they are very helpful.

Unless ... you happen to need the data on a weekend or holiday ... then post in forums and will likely get some pointers from fellow reloaders.

[grant22]

Thanks

[Bill Steele]

Search turned up nothing for me. What do you do when you have a bullet that doesn't quite match up to the bullet data in a manual? Example:

Let's say I have a MO Bullet lead .380 acp in 95 gr. The closest thing in my Lyman manual is lead 90 gr.

How do you guys do this or where do you start? There IS a 95 gr FMJ bullet data in the manual (same weight but way different bullet) which I understand as apples and oranges.

Also, thru some comparing I've done, it seems that larger weights of similar bullets usually get a smaller load of like powder. Is this because it's like horsepower vs. torque? A 4 cyl vs. a V8?

I plan on reloading some .380 soon, and I do have the lead 95 gr but need to know where I should start with developing the load. Using Bullseye, Lyman says to start the 90 gr 2.4. If I'm doing a 95 gr, I'd assume I would start at about 2.2????

Thx

In general, the bullet weight is the major factor for determining the appropriate amount of a given powder.

There are a lot of minor factors that weigh in as well, like how well the bullet seals the bore, the intergrity of the bullet under expected pressures and velocities (i.e. lead versus jacketed), etc.

You are correct in your reading that as the weight of the bullet goes up (for a given caliber and powder type), the amount of powder you will be using will go down.

When I am loading a new bullet that is not listed in any published data I have, I generally start with a load of the same powder for a similar bullet that is heavier and then work up slowly. By using the heavier bullet's published powder weight and OAL, I know I am on the "safe" side for starters.

When developing loads where you have no published heavier bullet load data starting point, you should use any interpolation with extreme care. The pressure a powder developes in a given caliber is not generally linear.

[bruceflinch]

What's an MO Bullet?

[Low-Pressure]

In general, the bullet weight is the major factor for determining the appropriate amount of a given powder.

There are a lot of minor factors that weigh in as well, like how well the bullet seals the bore, the intergrity of the bullet under expected pressures and velocities (i.e. lead versus jacketed), etc.

You are correct in your reading that as the weight of the bullet goes up (for a given caliber and powder type), the amount of powder you will be using will go down.

When I am loading a new bullet that is not listed in any published data I have, I generally start with a load of the same powder for a similar bullet that is heavier and then work up slowly. By using the heavier bullet's published powder weight and OAL, I know I am on the "safe" side for starters.

When developing loads where you have no published heavier bullet load data starting point, you should use any interpolation with extreme care. The pressure a powder developes in a given caliber is not generally linear.

+1 on this one!

[grant22]

MO Bullet = Missouri Bullet.

Thanks guys, very helpful.

[Whiterabbit]

I interpolate.

For example, I bought some Penn bullets @ 340 grains. NO load data. But I have cast performance data for 325, 335, and 395 grain bullets. So I graph that up and find the data VERY linear. So I just interpolate for 340 and I've got a new max to work up to.

In this case, max turned out to be .7 grains beyond too much for my gun (talking about ~40 grains charge here, so only a little off), I found pressure signs.

So if you are loading start values greater than than 3% below max (and you are, you are not using H110), then you should be more than find when working up loads.

[Whiterabbit]

By the way, and this is important. If you graph bullet weight vs powder charge for a particular caliber/powder, you will notice that the fit lines only work if you separate cast from jacketed, and especially non-lead (but unique non-lead dad is well known). Bottom line:

I will not substitute jacketed data for cast and vice versa for an "I want to develop this load" round. For a plinker, I just make sure I have a safety factor in there and play.

[tackdriver]

Rule of thumb is you can use the data for the next highest grain bullet. The velocity will just be lower. If you can find the data for your bullet grain in metal jacket, you can subtract 10% to get the load with a lead bullet.

[Whiterabbit]

oh dear.

This is the second time I've heard this (the first time at a reloading store). The rule of thumb: "lead uses less powder than jacketed"

Can anyone explain this rule? On the Hodgdon website, for the 460 caliber, using H110 powder, lead data SPECIFICALLY is higher than jacketed.

-----

Or in short, why does my research contradict popular understanding?

[Whiterabbit]

OK, so, here's what I'm talking about. The data here is collected from the Hodgdon website for 460 S&W using H110 powder. The bullets were then segregated based on type, then charted with respect to weight vs charge. Finally, fit lines were added to determine both oddball bullet weight charging and also whether or not if interpolation is even wise or a mistake. The following is the results:

(keep in mind pressure was NOT factored into this. max loads were chosen to reduce pressure spread from charge to charge.)



Conclusions:

1. Solid Copper bullet linear fit sucks. Never try to calculate loads for all-coppers with 460 and H110, just go with what the manufacturer specs and call it a day.

2. Linear fit for cast bullets is too good. with R squared @ .9997, I suspect there is a good chance that that load data was calculated, not derived empirically. Still, it makes it easy to derive load data for other weights. In my case, 340 grains.

3. Jacketed load data is LOWER than for cast. Thus, for a given bullet weight, say 350 grains, a jacketed bullet would require LESS powder than the cast alternative! not more!

Yet popular notion is to use less powder when switching from jacket to cast? That's not what this data tells me!

[grant22]

3. Jacketed load data is LOWER than for cast. Thus, for a given bullet weight, say 350 grains, a jacketed bullet would require LESS powder than the cast alternative! not more!

Yet popular notion is to use less powder when switching from jacket to cast? That's not what this data tells me!

Would you say this is because Jacketed is 'slicker' therefore requiring less ooomph behind it?

[Whiterabbit]

I don't like talking about the "why's" on the internet unless I have real data to back it up. There's ALOT of talk on the internet about the nature of reality in general and science in particular that is either not true or has no meat to it.

What I have here is observation. If there is a rule of thumb and my evidence shows the contrary, I want to know why the rule of thumb is in place, not what would justify the conclusions of my observation. Especially since this is the second time I've heard (first time I've read) the rule of thumb to subtract powder when loading cast.

But for the people who like to read stuff on the internet and pass it around on other forums as fact, I suspect it's copper fairies inside the limited 460 caliber guns that help push the bullet out when the skin is copper. Or maybe sprinkling their pixie dust on the jacketed bullets during loading because we all know that pixie dust makes an excellent dry bullet lube.

(tip: if anyone on the internet explains or justifies their facts by first saying "trust me.." or "think about it...", you know they are untrustworthy and full of poop.)