Might be a dumb question but...

[LloydXmas250]

I noticed when looking through reload data charts that they lighter grain bullets require more powder. Why is that?

Also, when using some charts they may not have a specific bullet type for the specific powder I'd like to use. I'll use for example .223 55 gr FMJ using H335. On Hodgdon's site, there is no 55 gr FMJ with H335, only a 55 gr SPR SP. So where can I figure the starting point for 55 FMJ with H335? Are those two bullets types close enough because of weight? Thanks.

[Table Rock Arms]

I wouldn't say they require more powder, but they are less pressure with the same amount of powder. For question number 2 if you reduce 10% to start which is good practice always, you would be good.

[LloydXmas250]

I wouldn't say they require more powder, but they are less pressure with the same amount of powder. For question number 2 if you reduce 10% to start which is good practice always, you would be good.

I'm sorry I'm not firing on all cylinders today. Can you clarify the first answer.

As for the second, are you referring to 10% below starting or maximum?

[Table Rock Arms]

I'm sorry I'm not firing on all cylinders today. Can you clarify the first answer.

As for the second, are you referring to 10% below starting or maximum?

The same amount of powder used with lighter bullets produce less pressure. So you can use more powder with the lighter bullets without creating too much pressure. Pressure is the limiting factor. If it wasn't you could just fill the case to the rim and load it up. And for the second answer, yes reduce 10% below max. And in response to the thread title these are not stupid questions.

Ryan

[bruceflinch]

When you are loading for Competition, there is a power factor involved.

PF = bullet weight x velocity x 1000

A lighter bullet takes more velocity to equal the same power factor. So a lighter bullet requires more powder to increase power factor.

See what I mean, Jellybean?

[EOD3]

All things being equal, a heavier bullet will be longer and have greater fiction resistance, mass, and "barrel time" which will result in greater pressure than the lighter bullet with the same powder charge.

[sequoia_nomad]

So where can I figure the starting point for 55 FMJ with H335? Are those two bullets types close enough because of weight? Thanks.

You can use the same charge data for different bullets of the same weight, assuming they are both the same construction (jacketed or cast lead). The tricky part is that the case overall length (COAL) will be different amongst different bullet profiles, so you will need to find a safe OAL for the bullet you are using. Try using the OAL for a 55 gr. FMJ listed with a different powder, and keep the charge for the 55 gr. SPR SP with your powder of choice. You should be ok. It's also helpful to compare your OAL with a factory round of the same bullet type and weight.

[killshot44]

Probably no need to worry about OAL with small bullets like 55gr and even 69gr. Speaking of which, 23.3gr of H-335 under 69gr SMKs is a wonderload.

[LloydXmas250]

Thanks for all the help so far. Another question since OAL was brought up, if I seat the bullet farther down and decrease the COAL, in general, what does that do to things like velocity and accuracy? Thanks again.

[sequoia_nomad]

Ideally OAL would be dictated by bullet length not seating depth. The farther into the case the bullet is seated the higher the pressure that will be created when the round is fired. Worst case scenario, the elevated pressures created by an over seated round can blow up the gun, causing its destruction and personal injury or death. Generally it is not a good idea to seat a bullet deeper than necessary (such as to fit in a magazine). Published numbers for OAL for a specific bullet shape are your safest bet.

[LloydXmas250]

Well that doesn't seem like it would really be to my benefit to mess with bullet seating depth. I'm mainly just going to be plinking and occasionally hunting.