Bullet shape Question??

"Is there a difference in load data between bullet shapes." (Edit to be more clear)
Yes.

The length of the bullet may change. The same OAL may put more bullet shank deeper into the case.

Should be ok using a starting load, and working up.

74man said:

Is there a difference in load data between bullet shapes.

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Yes. Bullet shape matters.

74man said:

I assume as long as they are all 124 gr that the shape of the bullet doesn't change the load data, am I right??

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No, this assumption is not correct.

The biggest factor is the amount of bearing surface you have and the composition of the bullet.


ETA. A hollow point will be a bit longer and longer bullets get seated deeper into the case. All things being equal, a deeper seated bullet will produce higher pressures at the same powder charge.

There can be minor differences. And if you are right on the edge of a safe load, a minor difference can be major! But unless you are really leaning on things, you generally are fine when loading different shapes of the same weight. As always, start low, work up, and pay attention!

bullseye308 said:

ETA. A hollow point will be a bit longer and longer bullets get seated deeper into the case. All things being equal, a deeper seated bullet will produce higher pressures at the same powder charge.

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When made by the same company, a hollow point will be a bit shorter.

74man said:

Is there a difference in load data between bullet shapes. Like is it the same Load data when using a 124 gr. FN, as using a 124 gr.FP, or 124 gr HP, or 124 gr SWC. I assume as long as they are all 124 gr that the shape of the bullet doesn't change the load data, am I right??

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Some ammo makers use the same load data for their bullets of the same weight. For example, look at Hornady's manual. They have three 124 grain 9mm bullets, and they share the same load data, though their OAL is different. Speer and Sierra do this, too.

fxvr5 said:

When made by the same company, a hollow point will be a bit shorter.

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Are you sure? At the same weight a bullet with a big air void would have to be longer since the diameter is fixed.

bullseye308 said:

Are you sure? At the same weight a bullet with a big air void would have to be longer since the diameter is fixed.

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The bearing surface is usually longer for a hollow point, but the OAL is usually shorter. At least that's been my observation in FMJs vs JHPs of the same brand.

74man said:

is it the same Load data when using a 124 gr. FN, as using a 124 gr.FP, or 124 gr HP, or 124 gr SWC.

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No, those are four different bullets with (probably) four different seating depths, (possibly) four different feeding characteristics, and (definitely) four different driving bands.

74man said:

I assume as long as they are all 124 gr that the shape of the bullet doesn't change the load data, am I right??

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NEVER assume! In this case, the assumption is not just wrong, but potentially dangerous.

bullseye308 said:

Are you sure?

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Yes.

bullseye308 said:

Are you sure? At the same weight a bullet with a big air void would have to be longer since the diameter is fixed.

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Everything else being equal this has to be true.

Differing shapes of the bullet noses can make a difference on how long the bullet is and how much of the bullet is seated in the case.

The composition of the bullet can make a big difference also. A 90 grain solid copper bullet will be about the same size as a 124 grain lead bullet.

It matters

Overall length and seating depth can create huge pressure differences.

Start low, work up slow.

74man said:

Is there a difference in load data between bullet shapes. Like is it the same Load data when using a 124 gr. FN, as using a 124 gr.FP, or 124 gr HP, or 124 gr SWC. I assume as long as they are all 124 gr that the shape of the bullet doesn't change the load data, am I right??

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As others have said. Bullet OAL and seating depths vary.

Hornady XTP 124 gr. = .579" OAL
Speer G.D. JHP 124 gr. = .560" OAL
Sig V-Crown 124 gr. JHP = .567" OAL
RMR JHP "Nuke" = .542" OAL.

And there are several cartridge OAL in load data for these.

As was posted, use start load data and work up.

reddog81 said:

Everything else being equal this has to be true.

Differing shapes of the bullet noses can make a difference on how long the bullet is and how much of the bullet is seated in the case.

The composition of the bullet can make a big difference also. A 90 grain solid copper bullet will be about the same size as a 124 grain lead bullet.

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See post #6.

74man said:

Is there a difference in load data between bullet shapes. Like is it the same Load data when using a 124 gr. FN, as using a 124 gr.FP, or 124 gr HP, or 124 gr SWC. I assume as long as they are all 124 gr that the shape of the bullet doesn't change the load data, am I right??

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Yes, because all of those bullet types will have a different COAL. To extrapolate load data, you need to compare bullet weight, construction (cast/jacketed), and type. Then start at the min and work up if you are loading a bullet that doesn't have specific load data.

Set two bullets the same weight but different shapes beside one another. If one is longer than the other, seating to the same OAL obviously leaves a different amount of volume in the case.

If you seat them so the base of the bullet is in the same spot, the OAL is different.

fxvr5 said:

See post #6.

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Post 6 is incomplete. It's certainly likely that a HP bullet will be shorter than a round nose bullet, but if comparing TC vs HP it's possible the HP is longer. It's all dependent on which specific bullets you are looking at. This is why most reloading manuals have a variety of load data for the same bullet weights for common calibers.

reddog81 said:

Post 6 is incomplete. It's certainly likely that a HP bullet will be shorter than a round nose bullet . . .

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I'm confused. I thought your post #12, "Everything else being equal this has to be true." was an agreement with what Bullseye308 said about HP bullets being longer. Was I wrong?

Everything else being equal the hollow point bullet is typically going to be longer than a bullet with the same nose profile. If you take material from inside the tip of the bullet it has to go somewhere else on the bullet. You can make the nose more rounded or add to the base of the bullet. There's no definitive answer that applies to all the various bullets out there.

reddog81 said:

Everything else being equal the hollow point bullet is typically going to be longer than a bullet with the same nose profile. If you take material from inside the tip of the bullet it has to go somewhere else on the bullet. You can make the nose more rounded or add to the base of the bullet. There's no definitive answer that applies to all the various bullets out there.

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Gotcha. I was thinking in terns of HP v. RN, in which case the HP bullet is shorter.

The bottom line is, to convert an FMJ RN bullet into a hollow point, you take small diameter bits of lead from the nose and spread them across the relatively large diameter base of the bullet. So, you add less length to the base than you took off the nose. The bullet still weighs the same but becomes shorter in the process.

Not just an HP, even little things like “flat tip”, “truncated” and various ogives can make a difference. These are all 147gn solids.



You can see the two to the left are shorter, despite being the same weight. That means if all were seated to the same OAL, the bullet on the right would have its base seated deeper than the other two.

According to Speer (the circled text) some 9mm powder/charge/bullet combination more than doubled the operating pressure with just a .030” seating depth difference! Would have been nice for them to provide any more detail but lots of folks “go by the books”…so if we trust their data it could matter that much.

So how different are our 147gn solids? The base depth difference would be .047” different from the longest to shortest, if seated to the same OAL.



That’s on the large side for many spark plug gaps but a lot of variation in the reloading world as far as seating depth.

74man said:

they measured within .001".

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Should make no difference with only .001" difference..

Check out other bullet lengths. https://www.jbmballistics.com/ballistics/lengths/lengths.shtml