9mm OAL again

[obiwankabaldi]

Sorry to keep bringing this up but I am looking to understand what I am doing.

I am using Bullseye powder and the manuals say 1.125" for OAL but all of my commercial ammo is measuring closer to 1.160" I have loaded a bunch at 1.140" and they shot great, though a little dirty. My question is should I go with the manual? Will that longer length affect the amount of residue? And how critical is OAL within the range lets say 1.125" to 1.160"? Lastly what is the advantage to longer or shorter OAL. I see that most guys are suggesting trying to get to the longest OAL that a specific pistol will allow. I have been reloading for a while and always went by the book. Thanks..

[GrumpyOne]

There is no need to start a second thread on the same topic. Just ask your question in your original thread....

[superdude]

Sorry to keep bringing this up but I am looking to understand what I am doing.

I am using Bullseye powder and the manuals say 1.125" for OAL but all of my commercial ammo is measuring closer to 1.160" I have loaded a bunch at 1.140" and they shot great, though a little dirty. My question is should I go with the manual? if you're using the same brand bullet as in the manual, sure. it's a good place to start. the most critical feature is to make sure it fits in your chamber at that length because some chamber dimensions vary.

Will that longer length affect the amount of residue? not hugely unless the powder charge is on the low side, as some powder burn less efficiently then.

And how critical is OAL within the range lets say 1.125" to 1.160"? with respect to pressure? pretty significant. with respect to reliability? uncertain as it will depend on your pistol. if the bullet fits the chamber and your magazine and runs reliably, that's the criteria. but the pressure is the important thing to consider. rule of thumb is to load on the long side to keep pressure low, as this tends to also enhance reliable feeding - if it fits in the magazine and chamber (though this is more of a guideline and isn't absolute). the pressure issue becomes more important whenever you load near the maximum recommended charge weight. you have less leeway for error then. it also depends on the powder you're using. bullseye is a fast powder and fast powders tends to be more sensitive to pressure concerns than others, but if you keep a close eye on it you'll be fine.

Lastly what is the advantage to longer or shorter OAL. again, the usual issues are pressure and reliability. it's usually a balance between the two. but if your current load runs and shoots fine with no signs of excess pressure (examples of classic pressure signs in primers can be seen at http://www.38super.net/Pages/Factory2.html), that's about as good as it gets. you might not need to worry about changing it - if it's not broken, don't fit it, and all that.

I see that most guys are suggesting trying to get to the longest OAL that a specific pistol will allow. sometimes they're trying to achieve a specific goal - load long for reliability etc. if you're loading for Major Power Factor then loading long is good because it helps to keep pressure down and that's important for 9mm because there is so little case volume in the first place and to make Major in the 9mm the pressures get really wildly high, especially with light bullets (115-125). oh, and for Major you want medium to slow burning powders. Bullseye would likely cause a gun to spontaneously disassemble.

I have been reloading for a while and always went by the book. Thanks.. books are a great reference and it's good that you're paying attention to detail. that's what keeps you safe. there is some leeway when considering overall length, the concerns mentioned are pressure and fit (magazine/chamber). if those are okay, then load-em up and blast away.

p.s. i posted this on the original thread as well.

[Joe D]

Most folks load a 9mm to 1.135"- 1.140". I load mine a little longer @ 1.150". That's with a 160 gr bullet. My Glocks and 1911s work well with this length.

[twodownzero]

The book is the minimum safe length for the data in the book, not a guideline as to what your gun will shoot and like.

COAL is determined by your gun. Load your ammo as long as your gun will safely and repeatedly chamber and eject (and fit in the magazine). Then use a chrono to set your velocity.

[CeeZer]

Here is a very nice write up by well respected Mr. Wobbly, where you can learn the bases:

http://www.czfirearms.us/index.php?topic=34225.0

Just disregard his mentioning 200gr bullet, work with your bullet and barrel.

[gmantwo]

I load my 9mm Major to 1.160. My complete load is 115 MG JHP, 7.8gr Silhoutte, WSR primer, loaded to 1.160. Makes right at 168-169pf and have never been bumped to minor.