Case length HELP

[Macmathews]

I am new to reloading and need some help with proper case length for any given caliber. I see what is shown in the handbooks for max lengths, but how do I figure out minimums. And what is optimum ?
Example , how close do I start to max ?

 

[gunsnjeeps]

Re: Case length HELP

There is also a "trim to length". That is the shortest you should go. Of course, if you have a couple that are .001 or 2 too short don't sweat it too much, shoot them they'll stretch.

Optimum is a little different, to find that you may have to try a few lengths. I don't think that a length in between trim to and max will make much difference unless the neck of your chamber is shorter than max. I'd say that a consistant length is more important.

 

[johnsobr]

Re: Case length HELP

Measurments are pretty conservative. If you trim them to the length specified in the book you should be golden like a retreiver. As long as they are not too long, cut square, and consistant you should be fine.

 

[awe2]

Re: Case length HELP

Case length or coal?Case length go by your books.Coal check with your rifle.By that I mean what your rifle likes the best.Put a bullet in a case that has been crimped enough to hold the bullet and chamber it completely.Extract it slowly,check coal and work your loads back .010 at a time.One length will be better than the rest.Then fine tune by .002 to .005.

 

[Macmathews]

Re: Case length HELP

Thanks for the tips guys.
I am speaking of CASE length only Not COL.
I bought some Nosler brass for .270WIN and noticed they are quite a piece shorter than handbook length, and that got me wondering

Thanks

Kyle

 

[Fuzzball]

Re: Case length HELP

Max case length is specifice by SAAMI to insure the cases will fit safely into a SAAMI minimum chamber. Most chambers are significantly longer that the minimum but it's wise to stick with the max length listed in our manuals.

The 'trim to' case lengths in the books are an arbitrary 10 thou less than max; it's no big deal and it's not critical if you go shorter. There is rarely - if ever - any advantage in striving for anything more precise than a length somewhere between those two points.

Have fun!

 

[adam3999]

Re: Case length HELP

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">
The 'trim to' case lengths in the books are an arbitrary 10 thou less than max; it's no big deal and it's not critical if you go shorter. There is rarely - if ever - any advantage in striving for anything more precise than a length somewhere between those two points.
</div></div>

I'm glad you brought this up. I wonder where everyone comes in on trimming to published minimum length versus below minimum to achieve consistency for the entire batch of brass?

I can easily set my Gracey trimmer to trim .308 cases to 2.005" but newer brass that is already at or near minimum length barely gets touched, often leaving the lot inconsistent. Sometimes the length is OK but usually the chamfer isn't optimal. Lately I have been dropping down as low as 2.001" so that all case mouths are consistently trimmed and chamfered, but it does make me slightly nervous that I'm out of spec.

My hope is that after 1-2 firings the brass will stretch in length slightly, and after being neck sized will be nice and optimal for my rifle.

 

[Fuzzball]

Re: Case length HELP

"Lately I have been dropping down as low as 2.001" so that all case mouths are consistently trimmed and chamfered, but it does make me slightly nervous that I'm out of spec."

There is just a commonly accepted 'trim to' length that's a rational but arbritrary 10 thou under SAAMI max; the trim-to length is NOT a specification. A shorter case won't blow up nor will it automatically impact group size. Just keep your cases at or a little under max lenght and shoot 'em. And the "max" length may or may not actually be max for a given rifle; usually it's not. Most chambers run 15-30 thou longer than the SAMMI size.


"My hope is that after 1-2 firings the brass will stretch in length slightly, and after being neck sized will be nice and optimal for my rifle."

It's the combination of firing followed by excessive FL sizing that produces most case growth, not so much when neck sizing. There is more variation in actual bullet grip between individual cases from the same box than you will see from 10 thou of neck length variation; that means there really is no "optimal" case lenght for any rifle.

You're over agonising case length.