ARTICLE: 101 of reloading dies.

Originally posted on Reloading Studio blog:


What are reloading dies? Do I need them to start reloading? Which ones? What’s the difference? Why are there multiple types of the same die?

Aim of this article is to discuss common types and features of reloading dies. To communicate the ‘why’ and the ‘what’, for anyone getting into relaoding.

As a side note, over time people develop a preference for brands, I am going to stay clear of that discussion, other than to say that there are many very good and affordable brands. Budget permitting, it may be worth considering something mid-range, rather than the cheapest option that you will outgrow or the most fancy option, which won’t be used to its full potential. Dies don’t wear out – take care of them and they will last forever.

The price difference

Boring stuff out of the way first… Why the price difference? A short answer is the differences in manufacturing process and equipment.

Dies are built to tolerances and configurability. Cheap quality gets you more ‘slop’ (big tolerances). Better quality dies have smaller tolerances and better adjustments. Although, chances are, over time you will assemble your own die sets from different brands, that do things just how you like it.

What is a reloading die?

A reloading die is something that will facilitate ‘a reloading task’.

Most reloading processes (i.e. assembling components into a small bomb, that you will detonate right next to your face) generally involve the same set of steps, regardless of what you are making. You may choose to do something your own way or follow only a subset of the overall steps (based on the cartridge or the components you have), you may chose to pay more attention to some steps, but not others… It all depends on what you are building and what it’s for. However, the fundamental steps will remain the same.

A reloading die is a tool that lets you perform one or many steps to process a component or assemble a cartridge from components. For example, after a cartridge is fired, the case is expanded and needs to be resized, before it can be used again. There’s a die for that. A bullet needs to be seated in the case – yep, there’s a die for that. And to make it fun, there are multiple variants of each, all doing the same thing in a different way.

The steps!

For most people getting into reload, the steps are:

  • Resizing fired brass cases.
  • Punch out the old (fired) primer.
  • Trim fired brass cases.
  • Seat a new primer (ha! actually, there are separate tools for this step).
  • Flare case mouth to accept a bullet.
  • Adding powder charge (also separate tools for this step, but not always).
  • Seat the bullet.
  • Crimping the case/bullet.

Based on your components and what you are loading, some steps may be skipped, some may need a little more attention, but the process will remain the same.

Below we will cover this process, with common steps and reloading dies.

Resize a brass case back to specification

Here’s where the fun begins!

First thing to note, most (if not all) resizing dies come with, what’s called a ‘mandrel’ (or ‘expander’). This has two functions:

  1. Size the case mouth to accept a bullet; and
  2. Punches out the old, fired primer.

Straightforward so far…

N.B. while these come installed in your dies, they can actually be considered consumable parts. Pins tend to break, not often, but they do… Worth remembering and grabbing a spare one for commonly reloaded calibres.

Resizing however, is a very long and complex topic. This is something you should research at length.

Full Length (FL) sizing die (specific to chambering)

Resizes the case to accepted specification (i.e. works in all firearms of the same chambering).

Almost all kits will include this die.

Neck sizing die with bushing (specific to chambering and neck diameter)

When a case is fired in your firearm and ‘blown out’ to the shape of your chamber (fire-formed) – it may be worth while just resizing the neck of the case, to set tension for seated bullet. Again, research is needed here about when and why, but this is very common option.

Neck sizing die with – collet (specific to chambering)

Similar to the ‘bushing’ type die, a collet die will set the tension on the neck-only for a fireformed case. Again, research is needed here about when and why, but this is very common option.

Tip: many shooters prefer this die over the ‘bushing’ option, myself included. Well worth researching this one in a lot more detail.

Trimming fired brass (die specific to chambering, with universal cutter)

Lee Quick Trim die (you will also need a cutter). It’s certainly worth knowing about it.

Trimming is needed when brass is stretched from use and no longer within accepted length range. This is a variable step in the beginning, but eventually you will need to trim.

This is one of those times where cheaper may not be better. If this is all you can afford – by all means do it! You won’t be go wrong, it does the job and I used this setup for a while. However, as you start accumulating calibres and add various precision steps to your reloading technique, you may want to look into a dedicated case (lathe style) trimmer. Using the Quick Trim die, you will certainly achieve results, but you will need to buy more dies (per calibre) and you won’t get a lot of ‘configurability’ in length and precision. Cheaper now, may end up being a lot more expensive later.

Flare (expand) the case mouth to accept a bullet

Variable step… If you are loading copper jacketed boat tale (bevelled bottom) bullets, this step should be avoided entirely. On the other hand, flat bottom bullets, especially cast lead/lead-alloy bullets do need the case mouth to be flared, to avoid damaging the case and shaving the bullet when it’s being seated.

Powder and expander

Most die sets for calibres that are known to take cast bullets will come with an expander die. Usually it has a combined purpose: ‘powder thrower’ attachment; and expander die.

Universal expander

If you are planning to load for many calibres, working with something uncommon or/and process a lot of brass at one time, a Universal Expanding Die might be a better option – you will know when you need it.

Bullet seating

This is definitely required. And you have a vast variety of dies to chose from. From whatever comes in the kit (most people) to eye bleeding expensive micrometre based dies. It all depends on your budget and specific use case. To start with, whatever comes in your die set is what you should be using.

Crimp the case mouth back to factory dimensions.

Variable step. You may need to crimp for some cartridges and firearm types, but not others.

For example, semi-auto firearms and revolver firearms must be crimped or bad things will happen, similarly for lever actions. You may need to crimp, because you’ve flared the case mouth and need to bring it back to proper dimensions. While you generally don’t need to crimp for bolt action firearms, where the case gets enough neck tension from the initial sizing process.

In any case, there are a few crimping types and corresponding die types. And as always, you may need to pick the right one, based on the chambering, the action type and how the headspace if measured on your specific cartridge (if you want to get technical).

Roll crimp

Oooo, this looks a lot like a bullet seating die, doesn’t it? That’s because it is. Most bullet seating dies will also function as a ‘roll crimp’ die, depending on how you set it up.

Taper crimp (or factory crimp)

Variable step, depends on the chambering.

You may need to use this instead of the roll crimp variant, depends on the cartridge.

“factory crimp”

Straight-up crimp around the bullet/neck.

That’s about it. This is more than enough to get understand reloading dies and what you may to get relaoding.

Keep in mind, that there are many other types of dies:

  • All in one seat-and-crimp die
  • Universal decapping die
  • Universal Expander die and kits
  • Bullet sizing dies
  • Bullet swaging dies
  • Bullet feeding dies
  • Lead hardness testers (includes a die)
  • Etc.

And it’s not uncommon to adapt a die to do more than what it was designed to do (you’ll get there eventually). As well, as various models of the same dies, various components within the same dies (like bullet seating stems, expander diameters, custom lock rings, bushing sizes, etc.).

To start with, none of this is needed, but well worth knowing that they exist, for when you do.

1 Like

Is it fair to say that if I bought a pack of factory ammo, fired it and then reloaded the brass, I would have no need for a FL sizing die as the brass has already been factory formed to my chamber?


However, you would still need to size the neck. My suggestion and in my opinion, the absolutely best option for this job is Lee Colette die. Learn how to use it, it’s awesome.

That said, at some stage, after a few reloads, you will need to do one of two things, either FL size or bump the shoulder back. For that you will need an FL die. probably not straight away, but you will need it. And when you start FL-sizing, you will start getting runout and that’s when you will also need a brass trimmer.

And when you start trimming brass, you will need chamfer/deburr tool :slight_smile:



When you are ready, maybe post a ‘wanted’ list of gear here, in Buy & Sell. I should have Lee Quick Trim cutters and dies for Mosin and few other calibres… I use “lathe type” trimmer now, because it’s better and doesn’t require me to buy more dies for obsolete calibres, but to get going, especially with budget constraints, Lee Quick Trim is a pretty good starting point if you get a cheap deal :wink:

Thanks for that. I am actually going to cry when the stupid shed goes in and I can start doing all this shit I’ve been planning for a year.

No you won’t, you will stand in the middle, look around and say to yourself, well, f#*k, how the hell did I just run out of space? :stuck_out_tongue:


I like dies that have a quick removable mandrel/decap pin assembly. Lee are not so easy with this feature, as the pin is not infinitely adjustable easily. RCBS & Simplex are though. Being able to remove the pin allows the FL die to be used as a minor crimp, especially with cast bullets. You can also neck size with the FL die by backing it off a turn or so.

I use Lee for all milsurps, because they are the best value for money and often the only choice, because there is (a) nothing else out there or (b) others priced themselves out of a market (RCBS as an example). For everything else (common) I use RCBS, they are comparative in priced for common dies and I think a better product.

I remove Lee mandrels quite a bit, for various reasons, mostly to assemble different dies when I need them, like making a 7.62x54R Lee Colette die from 303+308 dies (@Nomis take note).

Using FL die for crimping and what not, like smoothing bulges on cartridges with for cast bullets, so they can chamber (e.g. Reloading: M1895 Nagant (part 1)) is just muddying the waters here, I think. This is not a 101 topic :slight_smile:

Starting out, FL die is used for its purpose and seating die is used for seating or roll crimping (n.b. one should know when and when not to roll crimp, tapper crimp, and not crimp, different topic). There’s no need to go on tangents :stuck_out_tongue:

Oops I must be an advanced reloader…haha.
Just for the record, none of my ammo has bulges in it.

Must be :trumpet: :stuck_out_tongue:

You will only cry when you look at your bank balance after stocking up with gear and wonder “where did it all go”