Size matters

[Bill I Am]

So I am a newbie at the reloading. But I know enough to be dangerous.

My question has to do with overall length of the round. I am loading 9mm and the Lyman book says that for the 9mm 115gr, the OAL should be 1.090. OK fine.

But..I am a curious sort of guy so I measure some reloads that I purchased from Freedom Munitions and they were 1.15. Hrmmm..I know that they are the same load. So then I measured some 125 gr 9mm that I have, also from a reloader and they too were 1.15.

So what gives?

[stilly]

There is a MINIMUM and a MAXIMUM length.

The minimum that most books will list is the MINIMUM safest OAL.

If you seat the bullet deeper then you run the risk of overpressure and bad things can happen. Therefore you should not go smaller then the minimum for that load.

All rounds are different. The MAXIMUM is whatever you can load it to and still have it fit in your gun or magazine and feed/work properly.

Hope that helps.

[Bill Steele]

So I am a newbie at the reloading. But I know enough to be dangerous.

My question has to do with overall length of the round. I am loading 9mm and the Lyman book says that for the 9mm 115gr, the OAL should be 1.090. OK fine.

But..I am a curious sort of guy so I measure some reloads that I purchased from Freedom Munitions and they were 1.15. Hrmmm..I know that they are the same load. So then I measured some 125 gr 9mm that I have, also from a reloader and they too were 1.15.

So what gives?

There are basically two important OAL measurements. The first is the minimum OAL, that is the OAL published with any given load. It is the deepest the ballistician (or load developer) tested with the max load in the spec. That is the dimension in your Lyman you sight.

The second is the maximum length as spec'ed by SAAMI. It is there for manufacturers to make their guns so standard ammo will fit in the magazine, chamber, etc.

Your loaded length for any specific load you choose should end up between these two numbers. For 9mm I tend to load on the long side (1.140") as it seems to work with all my 9mm guns feed wise and is the minimum OAL for my favorite SD loads.

Make sense?

Have fun, good luck.

[Bill I Am]

YES, VERY helpful guys!

Of course, it would be nice of a book like Lyman would list the RANGE and not just the minimum size.

But then..THAT'S why there are forums like this huh?

[thegiff]

I tried a .40 load for my sig at the book minimum of 1.09" oal. They wouldn't feed, and I got something that looked like a 3 point jam. The new cartridge wouldn't nose into the chamber.

I then used a hammer style bullet puller to stretch them out, accidentally disassembling about 10 of the 100 or so I loaded, but the others were then reseated to 1.145"oal. They fed fine there, and I noticed the recoil dropped some and was noticeably less sharp. This was a max load with lead round nose semi wadcutters and true blue powder. The longer length is the max that will fit in my magazines without sticking in the mag.

[chuckshoots]

You also measured a 115gr bullet to have a different OAL than a 125gr.

With diameter being held constant (ignoring small variations due to manufacturing), the heavier bullets are longer so the 125gr should have a longer OAL. Were the other Freedom munitions reloads you measured also 115gr, such as your boolits?

[Bill I Am]

You also measured a 115gr bullet to have a different OAL than a 125gr.

With diameter being held constant (ignoring small variations due to manufacturing), the heavier bullets are longer so the 125gr should have a longer OAL. Were the other Freedom munitions reloads you measured also 115gr, such as your boolits?

Yes, the freedom munitions loads were the same, 115gr.