Max Length vs Trim to length?

[sgtmcbowflex]

Hello everyone,

I'm finallyy getting around to starting to reload and I can't seem to find a definitive answer for this one. Everything I've read on reloading is just a high level conceptual explanation, and doesn't really get to specifics like this for some reason.

So I'm currently only planning on reloading 9mm for right now, and all of my sized cases are coming in under the Max Length spec in the book. So does this mean I'm ok so long as my overall case length is at or below max after I seat and crimp?

The way I'm interpreting these numbers are "you're ok until you meet or exceed the max case length. Once you reach or exceed that length, then trim back to length specified in the book". Is that a correct interpretation of Max length, and trim to length?

Thanks in advance!

[wanneroo]

I'm just getting started myself and with 9mm. Right now just depriming and resizing, haven't moved on from that.

I've never heard anyone trimming 9mm pistol cases or any of the similar straight walled pistol cases. I'd imagine if one came in over max length I'd just chuck it in the recycle bin.

[Pkspawn]

You don't need to trim straight wall brass.

Just load them up.

You might notice better accuracy if you trimmed them all to the same length and cleaned out primer pockets etc.. But most people will not.

edit: Worry more about the OAL of the completed round.

[tripleS]

Straight wall cases in pistol caliber generally do not need trimmed. If they are all under the max length you can safely load them. There is no need to separate them by length or trim them to a standard.

If you have a few thousandth difference in length between cases it will ultimately affect the amount of crimp. In short, the longest (max length) will be crimped more than a case that is shortest (minimum length) when setting up your crimp die find a happy medium and keep an eye on the crimp as you go. If you see your majority are excessive you may need to back off slightly, or if the majority are not crimped enough you may need to add a little. You can easily make a dummy round (no powder/no primer) and check it in your barrel by removing your barrel and inserting the dummy round in the barrel, the end of the rim should be flush with the end of the hood or breech end of the barrel.

I personally like using a factory crimp die for 9mm, and have had good results doing so. 9mm is a caliber that is easy to get an excessive crimp on causing chambering and reliability with. If you get too much crimp it will not headspace properly. Some die sets have a taper crimp seating die and some have a roll crimp seating die. Mine have the roll crimp die, and I set it so it just removes the taper or flare and follow up with a factory crimp die.

[sgtmcbowflex]

Thanks for the replies and clarification. I'm still amazed that I haven't found anything written down that seemed to cover that really at all. Maybe legality issues... Who knows.

As far as the crimp goes. I'm using the Hornady 3 die set with a taper crimp. I was planning on loading my first 5 rounds tonight but then found that my book didn't have any data for Unique for 115 gr bullets which is all I have. Hopefully Dukes will have a powder in stock tomorrow that my book has data for. I checked Alliant's site, but they just seemed to list a max load for 115 gr. I could be wrong on that though.

[Pkspawn]

What book are you using?

Lyman's 49th edition does mention trimming straightwall brass, but also says, that the brass will most likely wear out before you'll ever need to trim it.

From Alliant website
Caliber 9mm Luger
Bullet 115 gr Speer GDHP
Min OAL 1.125
Primer CCI 500
Powder weight 6.3gn
Velocity 1,244

Are you cast or FMJ? You want to start 10% below what they list.. You always work your way up.. So start around 5.5 or lower.

Keep in mind, your OAL is important, seat the bullet deeper and you are increasing the case pressures ALOT. Thus slowly working the load up. If you need a shorter OAL. decrease the powder load and work it up again at the new OAL and check for signs of overpressure.

[Farbmeister]

The meaning of case length depends on gun its fired from. For a revolver a case length is not super critical... as long as the bullet is not sticking out of the cylinder little can go wrong. In a pistol, straight walled cases are used to headspace the round, and to long means that the action will not lock.

Since chamber dimensions have tolerances (ie they are not all the same) UNLESS YOU MEASURE YOUR SPECIFIC CHAMBER you simply need a reference... and the MIN/MAX Case length is that number that will allow the case to headspace any SAAMI chamber properly.

Now you could measure your chamber and find out what the number is EXACTLY.... but unless you buy the tools to do it you simply use what your manual says.

OAL means just about the same thing... but takes into account things like the magazine/cambering and the rifling in the barrel.

The only reason why you would want all the cases the exact same length would be if you knew the exact chamber size and were loading for it, or you were crimping into a cannulear of a bullet.

That's why LOTS of people use the Lee Factory Crimp Die... it crimps radially and length is not an issue.

[WVBob]

It's not an issue with straightwall brass. In 35 years of reloading I have never trimmed 9MM, .38/.357 or .45. The brass does not last that long.

[Arrdy]

Are you cast or FMJ? You want to start 10% below what they list.. You always work your way up.. So start around 5.5 or lower.

When starting low in charge weight, be on the look out for 'squibs'. If the slide doesn't cycle or seems very soft in recoil, check the barrel before firing another round. A wood dowel or cleaning rod works well.

[sgtmcbowflex]

I'm using the Hornady book that came with my press kit. Latest version I believe. I plan on using some FMJs to start, but also have a sizeable amount of Hornady XTP 115gr hollowpoints. From what I understand as long as the weight of the bullet is the same, the load data should be the same so long as they're both plated bullets.