Why different formulas for same sort of bullet?

I'm wondering why I can't use the formulas for jacketed bullets with the XTP bullets?
Click to expand...

You probably can. Just because Hornady doesn't have data for a given powder, doesn't mean you can't use it.

What is your purpose? (defense?, target practice? high recoil practice?)
Are you loading for 44 Magnum (I assume), or 44 Special?

What powders do you have access to?

If we know your purpose; and we know your powder(s); we can get you set up with a combination that works great.

For the record, it seems to me that Hornady is biased toward slow powders. Slower than I care for, in many applications anyway; as I am personally biased toward fast powders :p. I load with a lot of Hornady bullets. But I'd say less than half the time I'm using a propellant that's listed in their manual.

And it's not just a Hornady thing either. Today, I decided that I'm going to load some 45 ACP Speer 200gn TMJ (shaped like a SWC) bullets with TiteGroup. So I opened up Speer #14, and there was no data for TG. I went on the interweb and looked it up on Hodgdon's site, and they had 200 JHP data, but not for the Speer TMJ. But it gave me a good starting point. I'll be loading them up tomorrow. So it happens; often, actually.

I have Hornady, Sierra, and Speer manuals. And I have Hornady, Sierra, and Speer bullets. I bet if I went to my inventory of loaded ammo with those three brand bullets, less than half of them would be loaded with a powder listed in their manuals. We loaders do a lot of powder improvising.
 
Nick, I'm confused. A 230 grain 45 ACP FMJ and a 230 grain XTP 45 ACP will have the same overall length and the same amount of bullet seated in the case. Is this correct or are you saying these two bullets may have slightly different lengths?
 
They will be different. The xtp has a sharp ogive,conical in shape, and hollow, so it will naturally be longer than a solid lead jacket bullet wit a bulging round profile.
 
To be a bit more precise, the hollow point SHOULD be a bit longer. They will both have identical sectional density, or weight for diameter. D re again is then used to find ballistic coefficient. A higher BC will mean that the bullet is better able to resist drag. Not friction, per se, it will be better able to resist being slowed down by friction.

Anything is better than a cylindrical wad cutter. Tapering the bullet in the proper angles lessens drag and turbulence. Lengthening it by stretching it out improves bc some.

In general, a bullet that is heavy for the caliber, streamlined, an even artificially lengthened will have a high bc. Artificially lengthened? A polymer tip adds length and a streamlining effect with little added weight. Match hollow points aren't not meant to perform for hunting, they simply have a large air space in the copper jacket. The empty space allows the bullet to be made with a more streamlined design, and reduced drag.

This isn't too much related to .45 bullets, but it's important to know.

How is it calculated? Sectional density is a piece of cake. Then th bullets are test fire, and measurements are taken for velocities and rate of deceleration. The rates of deceleration are used to calculate drag and bc.

This information is easily found online. The math is very complex. Better to just look for the bc on the bullet maker's stat sheets.
 
Briandg,

But we still seat the XTP and the FMJ to the recommended overall length. Is this correct? In my loading manuals, most recipes for the calibers I load, do not specify seating depth; instead, there is a drawing of the cartridge with dimensions, which includes overall length.
 
This is such a complicated science. Loading various rounds to identical oal fiddles air space in the cartridge, which in turn affects ignition and burn, pressure and speed of pressure build up,and many other variables.

A person who loads a 147 grain hp Bullet using charge data and oal for a 115 or even 95 grain flat point jacketed bullet will have an unsafe load.

The only suggestion I really can offer is that you should rely on the bullet maker's oal figure, and use good judgment. Slow powders tend to be more tolerant of changes, it seems to me. Loading a fast powder to maximum, then cutting airspace by a third or more would be bad.

Here is what I would do,and this is not meant to be a suggestion.

I would look for load data that you like, but use slow burning powder. Load to oal recommended in hornady data. Start at low, and if it works well, leave it there. Pursuit of higher power loads isn't always the right thing to do.
 
44 Mag - 210 Sierra vs. 210 Speer

Maybe this will help. The bullet on the left is a Sierra 210gn JHC (Sierra #8620); and the bullet on the right is a Speer 210gn GDHP (Speer #4428).

Both bullets are the same weight. But it is quite obvious that the Sierra will seat considerably deeper than its Speer counterpart (when seated to the cannelure - as they should be). I would NOT consider published load data between the two to be interchangeable. Although there may be some "overlap" with some load data; the point remains that it is highly likely that the Sierra will produce more pressure - and quicker - if it is loaded identically to the Speer. The load work-ups I do with these two bullets are independent of one-another. They are that different.

They may be the same weight, but they are very different bullets from a load recipe standpoint.

1029151156-1_zpswfcy8fpw.jpg
 
Nick, that is the absolute best, common sense representation I have ever seen without need of a lot of complicated text!
 
Thanks so much

Thanks so much for all the great info. I stick to published formulas, but could not figure out why the difference between load datas for the same weight XTP and jacketed.

Great info.
Thanks
Live well, be safe
Prof Young
 
You must log in or register to reply here.
Back
Top