Is .004 too much?

kam582

kam582

New member
Another dumb question, I got my new Lee case trimmer and was setting it up for my .223 cases. While experimenting, trying to get it set to the proper length, I cut two cases .004 too short, and one .009 too short. I know, hard learner. My question, are they too short and should I pitch them. I know it's only three cases, but I don't spend all that time looking for them for nothing. Another question, I used a case that was the proper length to get the trimmer set close, along with the calipers. Any better way to do that?

I love the trimmer, it seems to work very well, once I figured it out.
 
Use em until they stretch, then trim again, you're fine. Factory Federal .223 cases in the bulk pack are 1.740" after one firing, so that's shorter then yours are if you are trimming to 1.750"
 
Not to worry and not EVEN a dumb question...BUT...

Open your calipers to .004" and see just how much it is. Case trim length has NO bearing on net loaded case volume and shorter is usually MUCH better than too long. SAAMI specs are estrablished just to keep us from letting the case get to LONG and jam the case into the leade. For all intents and purposes you could cut off 0.020" or MORE and not have any worries.

As long as you have enought neck to firmly grip the bullet and keep the bullet seated to the same OAL, the NET case volume will stay the same and you will be OK.

I ran some tests back in the past dark ages with a 30-06 and 150 gr Hornady SP's...I trimmed the cases by 0.015" increments until the case was about 2.20"long and starting with an OAL bullet seat around 3.27". I kept that 3.27" case loaded OAL length the same throughout the test. Can't remember the exact particulars, [beeep]'.

The POI changed slightly with each trim, but the velocity and accuracy stayed within Statistical limits...the NET case volume stayed the same...case length has NO bearing on internal bullet seated volume. I polished down a sizer button to 0.304" so the case would grip the bullet plenty tight.

Your talking about 0.004"...that's ALMOST unmeasurable except with fairly sophisticated measuring tools.

You can calculate the amount of area removed by trimming or bullet seating by the old PIE ARE SQUARE TIMES LENGTH circular volume formula...Pi x Radius squared x length of area removed by the bullet volume, in your case it's .004". 3.14 x .154 squared x .004" = ~0.00030 cubic in volume x 253 gr H2O/ci = ~0.075 gr H20...not a whole lot of displacement. See if you can weigh ONE grain/flake/piece of powder to get a perspective.

See your question WASN'T so dumb after all...there ARE no dumb questions...only not so good answerers. And you are NOT the first to ask it...I asked the same question when I was first starting out so many years ago and so have many others...Checkout 24hr campfire.

I gave you just about the same answer I received, with a smile and a pat on the back..."you'll learn as long as you keep asking questions" my mentor said..."now get back to sweeping the floor"...hahahahahaha

Luck
 
Originally Posted By: Irish_80Use em until they stretch then trim again, you're fine. Factory Federal .223 cases in the bulk pack are 1.740" after one firing, so that's shorter then yours are if you are trimming to 1.750"

+1
 
If you need practice getting closer to perfect I'll send you a couple thousands cases.

Then if you could sort them by weight and prime them...
 
I appreciate the offer, but after I butchered those 3 I got the hang of it.
smile.gif


I also appreciate the replies I get on this site every time I have a question. I can't imagine starting to reload without a resource such as this. Hundreds of years of experience at your fingertips can't be beat.
 
I hardly think trimming that small amount is "butchering".

If you REALLY want a learning experience, measure a few thousand cases to see just how far off, both too LONG and too SHORT new cases can be...you can also measure a bunch of fired factory cases found at ranges fired from different weapons.

THEN...take those 3 "ruined" cases...trim them all the the same length and fire them with whatever load you feel safe...several reloding cycles... DO NOT trim them,
but measuring them after each firing and record the groups, then do the same with 3 of your "correctly trimmed" cases...lastly...compare the groups to see any differences.

I'm guessing you will get about 0.002" "growth" after each cycle so in 5 cycles you will be back to your manual stated "trim to" length.

But why fret...just look in another manual...you might just see a totally different "trim to length", which is telling you a whole bunch of between the lines information.

And while you're at it, check out a bunch of SAAMI and trim to lengths for other cartridges. A quick glance through the Nosler manual and you will see it gives a MAX SAAMI COL and a cartridge length in the picture of 1.76"(Max SAAMI) but doesn't say whether it is a max SAAMI lengh or a trim length...Hogdons 2006 gives a trim length and Max COL for a specific bullet and the Accurate Armes #2 gives a max of 1.76", trim to of 1.74"(0.020" difference), and both a max/min COL...and Load from a Disk gives Max SAAMI COL's.

Then read the fine print in the reloading section...most manuals cover all aspects of reloading AND the reasons why some of the time.

Reloading manuals are all different, give different information on loads, fired from different weapons...a manual is just a guideline, NOT an absolute. If you learn anything, learn that.

You have to understand many reloaders start out wanting to reproduce "perfectly" what their first reloading manual gives...leave that to the perfectionist with a "perfect" rifle and "perfect" components...let them go nutz trying to obtain perfection in an imperfect world..."WE PERFECTIONISTS" ALL learn after a while no such thing as perfect exists...especially in a factory rifle.

But not to worry...I used to "earn" much of my reloading supplies by turning those crude and totally imperfect factory rifles into "almost" bugholers by being thoroughly versed in all aspects of this sport and applying that knowledge to their shooters...you have to be flexible and help make things fit.

This is not brain surgury or life and death(unless you go TOTALLY postal) it is just reloading...you gotta chill out and enjoy it, this is supposed to be fun.

Luck
 
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