Resize, Prime then Trim? Or is that wrong

Trim them before priming and clean the primer pockets, then tumble polish, then prime, and load, that's what I do.

Keeping it simple I:
Size and deprime
Trim
Prime

Leaving out any case cleaning and just a focus on size, trim and prime.

I guess we could easily prime and then trim. The .308 Win case length should be a trim to 2.005" and if you look at the SAAMI Cartridge and Chamber Drawings page 110 you will see the dimensions. The 2.005" is right in the middle between Min and Max case length.

Ron

ReedTX said:

Would I be able to prime this resized brass then trim (if required following measurement), or am I better off waiting to trim the brass then prime?

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I'd wait. When I trim cases, I use a drop of oil now and then on the case trimmer's cutting blades, and I make sure I clean that oil off, and out of my cases (sometimes by tumbling them) before I put any primers in them.
I don't want any chance of getting oil in my primers. It might not hurt a thing. But it might, and I'm not going to take that chance.

I’ll bear with you, but I’m not gettin’ bare with you.

It’s all bearing on whether you mind brass shavings in your cartridges or not. Having the primer in there can hang on to them.
I don’t want bare necks and lube them for bullet seating anyway, but the thought of brass in the bore gives me glitches. I already work hard enough to keep copper out of it.

When you are done with all case prep tasks, then you prime. After I trim, clean the primer pocket, chamfer, debur, run the neck brush in and out and visually inspect inside, then it's time to prime.

My process for brass is to decap, clean, inspect, resize, tumble (to remove the resizing lubricant) and then trim.

The logic behind this process is that any significant dimensional changes in the case will occur during resizing/expanding, so case length should be measured afterwards.

It also depends on your trimmer. If it indexes on the shoulder, then it doesn’t matter. If you’re using a Lee case length gauge to trim to length, the case shouldn’t be primed.

Priming should be the very last step.

Just prior to powder charging and bullet seating.
Please, please buy a manual or two as your next step.

Might want to get a Lyman or Hornady headspace gauge as well.

OP welcome to the THR. I agree the best next step is a manual. I find reading a manual a better way of absorbing info than on line for some reason. This will allow you to read and understand why each step is done in that order. Also a lot of hidden ( if you will) information as to the reasoning why each thing is important is explained. As you learn and understand things you will build on the process to add safety steps and refine what you need to do to produce better ammo. As long as you pay attention to details reloading is a fun and safe hobby to get into. I'll never forget pulling the trigger on that first set of reloads I assembled all those years ago.

Depending on what kind of trimmer your using. Lee makes a simple trimmer that the pilot goes through the primer hole for setting distance.

Like most have said wait till they are trimmed. And only load them when your going to shoot. This way your primer inventory and be used on other calibers if needed.

ReedTX said:

Hello - this will be my first batch, so please bare with me!

I have some once fire .308 brass that I have already resized and deprimed. I have not measured the brass (awaiting delivery of calipers) and my primers were delivered today.

Would I be able to prime this resized brass then trim (if required following measurement), or am I better off waiting to trim the brass then prime?

I have not gotten round to buying a manual yet. I will be getting one prior to loading any powder & bullets for sure.

Thanks all.

Click to expand...

Well first, unless you are shooting a match or something......you don't need to trim that brass. I'd leave that step out completely. But if you really feel the need to trim it, then the steps would be clean, size/decap, trim, chamfer case mouth, clean primer pocket, clean brass again, then prime/load. Always clean after trimming...get rid of all the brass trimmings before loading. Or at least put the trimmed brass in a tub and use your aircompressor to blow off as much of the brass trimmings as you can.

When you start thinking about case gauges you may want to give this old thread a read. The thread covers the differences between a headspace gauge and cartridge gauge. As for trimming there is a plethora of case trim systems out there. I have an old manual RCBS I use and then I was given a motorized version. Both work fine for my needs. I also like and use a RCBS case prep center and like the case trim systems there are a dozen brand names to choose from. Get some suggestions and advice on what is available and get what trips your trigger.

Start with the basics and essentials and work up your tools from there.

Ron

I'd not trim unless needed. It's needed if the cases are too long. As it's needed if you crimp for consistent length. Unless you use a lee factory collet crimp die.

I trim 30-30 every load cycle because I crimp every time. But 308, doesn't need a crimp unless it's going through a semi auto.

K.I.S.S., Wait.

ReedTX said:

Hello - this will be my first batch, so please bare with me!

I have some once fire .308 brass that I have already resized and deprimed. I have not measured the brass (awaiting delivery of calipers) and my primers were delivered today.

Would I be able to prime this resized brass then trim (if required following measurement), or am I better off waiting to trim the brass then prime?

I have not gotten round to buying a manual yet. I will be getting one prior to loading any powder & bullets for sure.

Thanks all.

Click to expand...

If you will permit a newb to weigh in......I'm about 8 months ahead of you, having gone back to reloading after nearly a 50 year layoff.

At this point, do nothing more until you get your calipers and at least one reloading manual, and 2 or 3 is more better. Manuals contain "how to" info in the front, and cook book type recipes for the various calibers in the back. The reason for more than one is that none of these are entirely generic. Almost all of them are produced by vendors and each is written from the perspective of what the vendor is selling. So while each has something valuable to offer, each will take you down some rabbit hole. But in general, there are common themes that show up in all of them. Those are the keys to focus on. Another reason for having more than one is that reloading data varies in most of them. There are no absolutes as far as START and MAX loads. Before you do anything, consult with more than one source. You will find load data is a range, more than a set of absolutes. Stay in the range to stay out of trouble.

One of those is trimming cases. I would strongly disagree with anyone who says that is not important. Case length tends to grow with each reload to the point case neck will eventually get jammed into end of chamber and that will get you a major pressure spike not related to anything but a constriction in the chamber. Found some ammo boxes in my Dad's old stash from 50 years ago, and he had made notes on them like "Barker" and "HOT". These were with middle of the road starter level loads, and no where near enough powder to be causing pressure problems like he was seeing. I remember most of what he was doing, and trimming cases was not part of it. My guess is he was running into dangerous pressure levels because the cases he was loading where being jammed into the throat of the chamber.

So when I was looking for a means to trim cases, the guy who sold me a large chunk of my equipment told me about the Lee case trimmers. The kind you chuck up into a drill, insert the rod, pin on the end of the rod passes through the primer hole to register on the shell holder. Trims cases to a very precise fixed length.....no measuring or anything on your part. For the 270 Win, SAMMI spec for case length is 2.540". Trim to length from reloading manuals is 2.530". The Lee trimmer will consistently trim cases to 2.538". Within less than 0.001 each and every time. But what that means is that with each firing and subsequent resizing, cases tend to stretch to 2.543 so each gets trimmed with each reloading.

That system consists of three components......the shell holder.......the cutter end.......and the calibrated length stem for each caliber. Each stem costs about $10. So if only doing one or two calibers, that option seems to offer the best solution as far as accurate, effective trimmer at a bargain basement price.

So my process takes place in 5 steps:
Case Prep:

Inspect fired case for damage. If it passes.......
Lube Case....brass outside and I run a mica coated wire brush inside neck, which cleans and lubes inside of neck for the sizing die mandrel. Lube is funny stuff. Must have it to keep case from sticking in resizing die, but you actually need very little. Less is more.
Deprime and size case.........then wipe off the lube. If I plan to tumble, will deprime only. Will resize after the rumble in the tumble.
Measure case length and trim as needed. New brass or once fired factory may not need trimming.
While case is chucked up in trimmer, hit it with chamfer tool to put micro bevel on inside of neck to help with bullet seating and debur outside of neck.
Blow out case with blast of compressed air to get any shavings or tumbler media blown out.

This is like a good paint job. Prep is everything and for me takes up well over half the time to load a round. Maybe more.

Prime Cases:

I seat primers by hand. Feel each bottom out, and it better be firm. If not.....and it's a loose fit.....that is indication case has reached the end of the line. Will be the last time loaded or if really bad, pull primer and trash that case now. At this point, I have a fully prepped case, with primer. Nothing left to do but drop powder charge, seat bullet and crimp.

Drop Powder:

I'm using mostly stick powders, so may use a powder measure to get close, but then weigh and trickle up each charge to get exact same charge. Slow, but I'm low volume and favor accuracy over speed.

Seat Bullet:

Again, I'm loading hunting ammo, and have found that once I get the load right, chasing the lands is not needed. Recently printed a 4 shot .75 MOA group with 3 holes touching at 100 yards.* I don't need to be better than that. So I'm seating to COL for the bullet, and all under SAMMI spec length. (* I didn't think that I or the gun were capable of that level of accuracy, but we did it. Fun stuff!)

Crimp:

I'm loading hunting ammo, none of it anywhere near the lands, all of it to nearly book COL, so I crimp each round. I'm using Lee Factory Crimp, vs the crimp feature of dies that allow it.

And that, as they say.......is that. I'm finding that once the load is sorted out and dies are setup for what I want to do, I can load a box of 20 rounds......start to finish....in just over an hour. Could do double that in far less than two. That is a lot of hunting ammo for a guy making one shot kills.

One more observation of a newb..........one area where all reloading manuals fall flat is on topic of load development. ALL say you need start at bottom and work your way up. They do not tell you how. LEE manual described what would be an Optimal Charge Development (OCD) process in one brief sentence.....more as an afterthought. Most of the rest are entirely silent on it. Concept of load ladders and such in these manuals are mostly nonexistent.

Ironically, one of the better methods I've seen was from a Sierra Bullet guy on a forum. Not sure it was on the Sierra Bullet website however. And their last manual is out of print, so can't tell if it was in there.

ReedTX said:

Thank you for all your comments.

Is it normal for once fire brass to be so close to maximum length of 2.015?

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My experience says yes, very common. All has to do with the chamber it was fired in. Learn to bump the shoulders back properly, trim and fire again and you will most likely see less stretch. It's called Fire Forming.

ReedTX said:

Hello - this will be my first batch, so please bare with me!

I have some once fire .308 brass that I have already resized and deprimed. I have not measured the brass (awaiting delivery of calipers) and my primers were delivered today.

Would I be able to prime this resized brass then trim (if required following measurement), or am I better off waiting to trim the brass then prime?

I have not gotten round to buying a manual yet. I will be getting one prior to loading any powder & bullets for sure.

Thanks all.

Click to expand...

There have been many responses so far and I agree with them.

But to add, as you start to reload more cartridges, it is good to wait to prime the cases until just before loading. If you prime cases ahead and then need primers for a different cartridges, you may not have a sufficient supply of primers on hand.

Also, get a manual. They have lots of good information and provide good reading.

Add annealing. I know it's a whole rabbit hole in itself.