Does bullet type matter?

[NotSoFast]

Questions, questions, questions.

In looking through the different loading manuals, I seldom see a different workup for JHP and FMJ. Is that because the bullet types are interchangeable for that particular load?

Can I take a 9mm 115gr JHP bullet and substitute it for a published 9mm 115gr FMJ load?

Or do I need to adjust?

And just how would I go about doing that?

Also, when the load specifies a specific brand of bullet, can I substitute another brand of the same type and weight?

I want to be safe when I am loading, but at the same time I want to be flexible with my loads when it comes to bullet type within a specific weight.

[ar15barrels]

I'm going to hazard a guess that you have not read the "getting started" chapters of your reloading manuals very closely.
Are you perhaps using those free books from the powder makers?

Load data published in real loading manuals (hard cover bound books) are for a specific combination of an exact brand/type of bullet when used with a specific case, specific powder and specific primer.
The loading manuals will caution you that changing ANY single component from the recipe will require you to work up your own loads.

You can not interchange bullet types or brands as all behave differently.

[Fjold]

Like Randall says, you have some reading to do.

You cannot use the maximum loads using different components. If you start your load development at the "starting load" listed in the manual you can generally substitute bullets of the same weight even if they are of different construction.

But, you are responsible for monitoring for pressure changes as you move up in power with that load as you are going into untested areas.

[NotSoFast]

I'm going to hazard a guess that you have not read the "getting started" chapters of your reloading manuals very closely.
Are you perhaps using those free books from the powder makers?

Being a new reloader, I have read the beginning chapters in all the manuals I own. Books from the powder makers, like Hodgdon Annual Manual? Yes. Like the Hornady Manual? Yes. I have also read the Lyman reloading manual as well as the A_B-Cs of Reloading, or at least the beginning information on primers, powders, cases, bullets, and the how-to chapters.

Load data published in real loading manuals (hard cover bound books) are for a specific combination of an exact brand/type of bullet when used with a specific case, specific powder and specific primer.
The loading manuals will caution you that changing ANY single component from the recipe will require you to work up your own loads.

You can not interchange bullet types or brands as all behave differently.

I realize you are trying to caution me, and I appreciate that. So tonight I went back and went back over the "getting started" sections of the manuals I own (see above). The only cautions about interchanging bullet types or brands was in the Hornady manual. And it said to go back to a minimum load, or drop back 10% from the maximum, and build from there if you do change bullet types or manufacturers. Neither it, nor the other manuals said anything that I can find about not doing it altogether.

Just for reference, here are the three paragraphs from the Hornady manual that refer to bullet choice:
(from the last paragraph, pg. 43 of the 7th edition of the Hornady Reloading Manual) "Bullet selection for the reloader is partly science and partly an art. The reloader is in charge of the choices he or she makes. ... The best advice we can give you is to use the ballistics tables in the web along with the loading tables in Volume 1 to see how trajectories and velocities well perform with a load."

Then, from the Keep It Safe section, pg. 72, tip #10:
"10. REDEVELOP LOADS WHEN YOU CHANGE COMPONENTS. Change a primer? Change a cartridge case? Don't automatically assume an old load will work well with new components. Start low again and build up."

Finally, from pg. 74:
"Nevertheless, if a load is developed for one style of bullet in a particular weight, it is wise, and we recommend, reducing the powder charge slightly with a different style of bullet of the same weight."
(Type bolded by me.)

So, I thank you for indirectly giving me the correct answer, which is to drop back in powder 10% (or more) and redevelop the load if I change bullet types.

[NotSoFast]

I did. And I agree about falling back and redeveloping the load now that I have reread it. See my reply to ar15barrels above.

I will be sure to be more clear and specific the next time I ask a question.