Newbie Case Size Question

Discussion in 'Reloading' started by Greywolf18, Jan 14, 2009.

  1. Greywolf18

    Greywolf18 Well-Known Member

    Dec 18, 2008
    I have a question for all you long time reloaders out there. I am new to reloading and several of you have already helped with some previous questions to which I can't thank you enough! I have another question for everyone, I have searched throughout books and this forum but could not find an answer to my question. Its in regards to case length. I am starting on reloading .223 for an AR. I have looked up in the Hornady book that the COL is 2.25" using the 75gr BTHP bullets. However, I am curious as to what I should trim the brass too. I picked up a box of Hornady 75gr BTHP bullets to break in the barrel until all my reloading stuff gets here. I measured the case on those bullets, but when I go to trim mine, I can only get the case to within +/- .005". Is this acceptable? How do I get to an exact measurement? I'm kind of anal about that, but don't know if I'm just over doing it or what? I am using a forster original trimmer and it took me ruining several cases by cutting them too short before I got to within that measurement. How can I pre-measure that distance without ruining more cases in the future? I know I'll have to change the case length when I start in on my .308 so how do I go between the 2 without ruining more cases until I get within the proper length? The price, and more importantly, the availability of brass sucks so I am trying to conserve what I do have. Thanks again for all the help and advice!!!
  2. britz

    britz Well-Known Member

    Mar 11, 2007
    I don't use the Forster, but I use an RCBS and I beleive they are somewhat similar. You should be able to get within .001" from case to case. If you are having trouble getting it close than I would look at the shell holder and see if there is a problem there. Also, I assume that you are using a 22 caliber pilot on the cutting head. Having too small of a pilot, or none at all will allow the neck to wobble during cutting and you may then cut the case irratically.

    Generally speaking trim lengths will be .01" shorter than the maximum case length so I think you would be trimming to 1.75". for a 223 (admittedly I don't load for the 223 however).

    When I set up my trimmer I start with a case that is too long and set the trimmer so it starts to cut. Then I measure the case with a standard dial caliper and if it is too long I adjust it to cut shorter little at a time until you get to the right length. Seldom do I wreck a case due to over cutting when I set the cutter up. The RCBS has a screw type fine adjustor for the cutting depth with hash marks on the ring so I can keep track of how much I am adjusting the cutter. If the Forster doesn't have that fine adjustment then I would wait for some other advice.

    Good luck, Mark.

  3. AJ Peacock

    AJ Peacock Well-Known Member

    Oct 7, 2005
    Actually, I don't concern myself too much with the 'absolute' length. The length listed in the books is the 'standard' lengths and all chambers should accept brass of that length. I normally just trim my brass lots so they are all the same and they are all square (the most important part).

    Getting in the neighborhood with your trimming will be just fine. As long as they are all shorter than your chamber.

    Sorry I can't help you with the setup of your trimmer.

    Good Luck and I hope this helped, And welcome to the site.
  4. Greywolf18

    Greywolf18 Well-Known Member

    Dec 18, 2008
    Thanks for the help guys. Yes, the forster trimmer does have a small screw for fine adjustments. Yes, I am trying to get the cases to 1.75". However, I am getting it to 1.746-1.752. Once the depth is set, I can get consistant cuts. So I have been making a cut, measuring, then making the slightest turn on the screw, cut again, measure, turn, etc. However, I cannot get to 1.750" I just being too anal and once I find 1.748-1.752 just lock it down and do a batch of brass with that setting? So basically I can get it to +/- .01", but am trying to get it to within +/- .001" this too anal? Should I get within +/- .002-.005 and say good enough for government work?

    My dies finally came in today so I am hoping to do a batch of brass tonight so I can start attempting the rest of the reloading either tomorrow or the next day...depending on when I get the brass right and I read the manual for the 10th time to make sure I don't screw it up :D Thanks again for the help.
  5. Charles B

    Charles B Well-Known Member

    Sep 28, 2005
    I usually sacrafice one piece of brass for each cartridge I reload as a case length gage. Keep those on the shelf with the trimmer and when I need to set up for trimming a cartridge I use the case gage I set aside to adjust the cutter head. This should get you close to your desired length measurement.
  6. Winchester 69

    Winchester 69 Well-Known Member

    Mar 29, 2007
  7. MagnumManiac

    MagnumManiac Well-Known Member

    Feb 25, 2008
    I have to agree with AJ Peacock, the most important thing is that your brass isn't too long for your chamber, a few 'thou' over or under the 'trim to length' will make absolutely no difference to how your rifle shoots, as long as they're all the SAME and SQUARE, with a slight chamfer inside and out.

    When I start with new brass, I run them all through my neck sizing die to insure they are round, measure them all, find the shortest one in the batch, skim trim it to make it square and trim the rest to that length, chamfer and deburr the flash holes.

    To get your trimmer set each time, you need to have a 'trim to length' case set aside as a 'set stop' to go into the trimmer each time.

    I also have 'dummy' rounds set up for my bullet seating dies, with each different bullet style I might use in that cartridge, a 'dummy' round contains no powder or primer, just the projectile seated to the OAL that you have set for your gun/load combo.
  8. Ozzieman

    Ozzieman Member

    Jan 6, 2009
    HORNADY 7th shows the following for 223 and for 223 service rifle data.
    MAX C.O.L. 2.250
    Max case length: 1.760
    Case trim length: 1.750
    I also agree with AJ Peacock, the important thing is consistency.
    I use a Wilson case trimmer and there are times that once set I am surprised at the consistency that I get with there trimmer.
    Other people will tell you to have your chamber measured for depth and cut the cases to 0.0000000001 less than the chamber length.:)
    I am kidding at the number, but I do have a friend that if he could, he would trim that close.
    The important thing as others have said, too long is the one thing you don’t want your cases to be.