.308win Neck Trim and Collet Size?

Wow, the world of reloading for bench or match ammo is overwhelming. Anyway, rather than spend $60 on 100 lapua cases, I spent $60 on an RBCS neck trimmer to start on the over 1000 existing cases I have of winchester, remington, and federal brass.

I know with a case neck trimmer that I will typically want to get the neck wall thickness concentric all the way around. But how thick should it be?

I'm using an RCBS competition FL die for all the range pickup brass that hasn't been fireformed for my bolt gun. Then a Lee Collet Neck die. How much should I turn down the neck die? How tight do I want the case mouth? I don't want to have trouble seating the bullet, but I also don't want it moving in or out while it sits in the ammo box.


  • Rocky RaabRocky Raab Member Posts: 10,889 ✭✭✭✭
    edited November -1
    First of all, Lee, take this for what it's worth.

    Using all those tedious benchrest case and ammo tricks won't hurt. BUT, unless you're shooting that ammo in a custom-made benchrest gun, it won't help, either. Doing match prep on ammo for a factory rifle is like cutting firewood with a caliper and scalpel: Perfectly done - with no benefit.

    Neck turning is one of the most tedious and least productive things you can do with a factory loose chamber and throat. It can actually make accuracy worse, because the round has more room in which to get misaligned. A thicker neck might even be better!
    I may be a bit crazy - but I didn't drive myself.
  • MIKE WISKEYMIKE WISKEY Member Posts: 9,259 ✭✭✭
    edited November -1
    spend the $60 for the lapua brass and sell the range pick-ups for scrap. the neck thickness will depend on your chamber dimensions, most bench rest rifles have 'tight' necks (i.e. NOT to sammie spec's).
  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    you'll be needing one of these

  • leeblackmanleeblackman Member Posts: 5,683
    edited November -1
    I figured somewhere about .015 to .016", thanks JustC. Hey what brand is that, mine totally isn't that cool?
  • nononsensenononsense Member, Moderator Posts: 10,575 ******
    edited November -1

    The tool in JustC's photograph is by K&M Services.

    I have several of the Sinclair version, each set up for a specific case used in a specific rifle chamber.

    For general accuracy requirements, buying Lapua cases can be a real time and aggravation saver...

    Case necks should be turned for absolute MINIMUM clean up of the outside diameter when used in factory or non-match chambers.

    Neck tension can set for as little as 0.0015" so long as you aren't traveling down railroad beds to get to your shooting destination.

    Neck tension can play an extremely important role in load development. It can also change over time...

    Here is an excerpt from a well written article about neck turning and the circumstances surrounding the practice:

    "Outside Neck Turning - Factory/standard chambers

    The goal when turning necks on cases for factory or standard cut chambers is to uniform the case necks without removing too much wall thickness. You will not be turning the case neck to a specific dimension. You will be trying to remove the higher or thicker spots on the case neck and get the overall thickness to be fairly uniform. That means on some cases you may not touch parts of the neck with the cutter where the wall thickness is at its thinnest. What you are striving for with standard chambers is to have the neck turning process cleanup approximately 70 to 80% of the neck surface. You really don't want to remove much more than 0.001" of material. On most tools, setup will be a bit of a trial and error process. There are adjustment devices and micrometer style neck turning tools that make setup a bit easier but these aren't really necessary to set up a tool to prepare cases for standard factory chambers."

    This is the link for the entire article:


    And another with good pictures for illustrations:


  • JustCJustC Member, Moderator Posts: 16,036 ******
    edited November -1
    the neck turing tool off to the right, is a K&N as has been staed. The neck thickness micrometer is the Sinclair model.
  • FrancFFrancF Member, Moderator Posts: 35,278 ******
    edited November -1
    x10 on that!
    quote:For general accuracy requirements, buying Lapua cases can be a real time and aggravation saver...

    The extra few quality steps at the factory save me a boat load of time.
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