Question on cartridge length

[ar10]

After finally getting part of my order that included the Forsters case trimming kit. I can't find a go/nogo on cartridge cases. I'm loading .308 winchester cartridgles an wondering if anyone might have a link that I could look at.
Right now I have headstamp CPC, R K, Winchester, F C, and MMY. I took a box of new Winchester .308's and measured them. All of them measured 2.0065 to 2.0075. So I started trimming based on the low end of the new cartridges, 2.0065. I figured if I'm between 2.0065 and 2.0080 I would be pretty close. The problem came up with F C cartridges which measured 2.0000.
I'm hoping that someone might be able to give me link to what min/max length of .309 cartridge should be.

 

[Bullet]

You might try here -

http://www.6mmbr.com/308win.html


308 Winchester - Trim-to Length: 2.005" - Max case length 2.015”.

I’m not sure what you’re using to measure your cases. My calipers only measure too 3 decimal points (.001)

Your cases will grow after you fire them and resize them. Don’t trim cases unless they are above the trim length and don’t trim them below the trim length. After you fire them and then resize them, then measure them and see if they need trimming. Depending how much they grow after firing and resizing you may not have to trim every time. As long as your between the Min. & Max lengths you’re OK. Always resize them before you measure them to see if they need trimmed.

Sounds like you need a reloading manual.

Maybe you are new to reloading (we all were - nothing wrong with that) so -
Cartridge length - is the cartridge = case and bullet.
Case length = just the case.

Here is a good place for definitions -

http://www.saami.org/Glossary/index.cfm

Hope this helps.


.

 

[ar10]

Bullet:
Thanks: Yes very much a virgin. Don't even have my press yes. (should come in today sometime).
I got the trimmer, (Forster), and the RCBS cleaner last Fri. Been cleaning brass all weekend.
All my tools are either Browne/Sharpe or Starret, (stuff I had while working in the aircraft business). The Brown/Sharpe is one of the first digitals that came out, .00000 accuracy.
The Hornady reloading manual is coming with the press today. The press is a single stage "Lock-n-Load" from Cabale's. I bought the complete kit and am not sure yet what all is in it.

I have about 500 cases of .308 I've saved over the past year, most with civilian headstamps and some mil stamps. I've cleaned about 300 cases and was trying to get a head start.
I've also saved all my other cases: .45 GAP, 9mm, 40SW, Mil 30.06 (M1), 7.62x39 (cz 527) and the AR10B.
I figure the price is going to keep going up and ammo is going to get harder to get,( I'm a little concerned about this micro-stamping technology). Anyway a couple of guys at the range have been reloading some of my 39mm ammo and the accuracy really improved which really sold me on reloading.

 

[Sunray]

"...some mil stamps..." Separate those from the comercial brass. Milsurp brass is a bit thicker and you have to reduce the charge by 10% and work up. They usually have crimped in primers too. The crimp needs to be removed before you can reprime. Relax. It's a one time nuisance. You do want to be sure your milsurp cases are boxer primed too. Look in the case. One primer hole is good. Two is not.
"...All my tools are..." Just fine. You only need 3 decimals places, but having 4 isn't terrible. Tolerances just aren't that close.
"...Hornady reloading manual is coming..." Read it before you do anything. It should have a chapter with M1 Rifle specific loads too. When you get that far, both the .308 and .30-06 love 165 grain hunting bullets and 168 or 175 grain match bullets with IMR4064 and regular large rifle primers(seated properly).
"...can't find a go/nogo on cartridge cases..." There aren't any. You can get a case length guage though. Usually used for loaded ammo though. The best guage for a pistol is the barrel. Take it out and drop the loaded cartridge in the chamber. Should be sitting flush with the back of the chamber. Works with rifle cartridges too, but that takes more fumbling.
After trimming any bottle necked rifle cartridge you will need to chamfer the inside of the case mouth and deburr the outside. Deburring you know about. Chamfering aids in seating the bullet. Just enough to ease the inside of the case mouth so the bullet will sit in it.
Semi-autos require Full Length resizing every time. Some people will insist that you must use Small Base dies for semi's, but FL dies will be fine. FL dies have worked just fine long before SB dies existed. Check the sizing die. It'll have FL stamped on it if it's an FL die. SB if it's a Small Base die. Either will do nicely.

 

[ar10]

Sunray:
I printed out a pretty detailed article showing the difference in detail between the Mil and commercial cases. I am keeping them seperate. What noticed was the difference between manufacturers on overall case length. (Winchester: 2.065, FC: 2.045, MMY: 2.012 every brand was pretty consistant). I also seperated the commercial by brands as well.

I am going to read the book when it gets here.

I don't have a deburring/chamfer tool yet but ordered one from Forsters yesterday. (they have a combination tool).

Resizing still has me confused. I already received the die set from Hornady. It's a 2 die set full length. What's confusing is whether I need another .308 die specifically for re-sizing or if the full die set does it. Guess I'll find out when I read the manual.
The Garand is a different "beast". All of my ammo came from CMP, "Greek import". I bought 2 cases, 1000 rnds in each case. The M1 is a Nov 1942 issue, and every part is original. I've put about 400 rounds thru it and every round has a nice ding at neck where the spent round hits the op rod. I'm not sure how to fix that problem yet but I've seen it happen on other Garands.

 

[Ol` Joe]

I printed out a pretty detailed article showing the difference in detail between the Mil and commercial cases. I am keeping them seperate. What noticed was the difference between manufacturers on overall case length. (Winchester: 2.065, FC: 2.045, MMY: 2.012 every brand was pretty consistant). I also seperated the commercial by brands as well

Brass OAL isn`t that strict that one needs to keep it exact. The max case lenght for a 308 is 2.015" the trim to lenght is 2.005" As long as the brass falls between these lenghts they are fine, trim when they excede the max.

You also don`t have to trim back to the recommended "trim to lenght". The purpose of the lenght max is to keep the case mouth from jamming in the throat of the chamber. As long as the case is shorter then the chambers lenght you are fine. Trimming the recommended 0.010" off the max does however reduce the amount of times you will trim a case before it wears out. Trimming to min should keep OAL within acceptable lenght for 3-4 fireings. If you crimp you will want to keep the cases close in lgt to insure even crimps and MAY have to even a couple cases up from time to time. A couple thousanths won`t matter much here either. Ammo, as in everything man made has some expected tolerance. The manual will show the range for the important measurements. Stay in them and I doubt you will ever have a problem.

Be sure to measure AFTER resizing your brass. The brass moves foreward when sized and can, if your chamber is a bit large, grow a suprising amount. Neck or partial full sizeing can reduce growth and extend case life. I`d recommend staying with full sizeing until you have a good grasp of the basics and are ready to move to the next level in precision.