Cutting Down Necks

[LynnJr]

WhiteRabbit
What I described is a very simple trimmer most can make at home. The plus is it works better than most store bought trimmers and costs almost nothing.

[Whiterabbit]

sounds good too. and a 3/8" endmill is something available on craigslist for a song too, since all it'll be used for is brass. Assuming someone didn't want to pay $20 at their local machine supply shop.

[J-cat]

I have the equipment to make a test batch. What I need is equipment for production. That is why I want to know how well these things cut. I don't want to overheat the brass and I don't want any blisters on my hand.

The chop saw idea would work provided the chop saw works. I don't have any confidence in HF electromechanical stuff. How many cases does one last? I figure I can use a Wilson case holder instead of a jig.

[J-cat]

J-Cat
If you have the reamer in your posession run it into a piece of barrel about 2 2-1/2 inches long. Only run the reamer in until you reach the shoulder then go in about an 1/8 inch more. Basically you are making a barrel stub like most accuracy gunsmiths provide with each build.

Run down to your local supply house and get yourself a 3/8 inch end mill and a shaft collar.
Flip your stub over and drill out the bore to 3/8 inch so the end mill will slide right in.

You have just built yourself a case trimmer you can run off of a drill. Spin the end mill until it is very close and lock down the shaft collar.

This is how meplat trimmers work and what benchrest shooters use to adjust case length.

But how do they work at removing more than .010"?

How do ammo manufacturers cut cases to length? The took marks on the case mouth are like teeth, ratchet marks, or something similar.

[LynnJr]

J-Cat
An end mill will cut brass like its butter and 0.200 is nothing. You can drill a hole 90 degrees to the bore to let all the chips out.
I just re-read my post and it sounds like you need expensive equipment and fixtures to make what I describe and you do NOT.
A reamer chucked into a drill will cut stainless like a hot knife through butter.
The difference between most trimmers boils down to one thing the quality of the cutter.
When you use an end mill and power it with a drill it will last a very long time.
I will dig one out and post some pictures.

[J-cat]

That's OK.

I got a Trim It from Big Bronco and it is what I need. It cuts fast and accurately. I may not even need to use my other trimmers.

[3006mv]

.2"? good grief.

I've done a few hundred cases of a 7mm-223 wildcat. basically a 300 whisper (you can call it blackout if you want) necked to 7mm. The cut is more than .2".I just put them in a standard trimmer and powered though it.

If I wanted match grade brass, I would need to:

power trim through the bulk
Chamfer/deburr
Trim again to get a precise length
Maybe deburr, maybe not.

But for within say .005, not really an issue.


There is no reason to overthink this. Unless your trimmer can jam through a case in 1-2 seconds, you might overheat the cutter. But seriously, no need to overthink, especially for a tester batch.

Nice shoulder, very Ackley like.


OP HF chopsaw or belt sander

[JMP]

Any of the electronic trimmers worth beans should have a blade with no issues taking down 0.2". It would just be way too tedious with a hand trimmer. LynnJr has a lot of tricks to get things done efficiently with little money, which are good tips. The problem with buying gun specific crap is that they mark it up 1000% as a speciality item as a lot can be accomplished with regular machinery.

[LynnJr]

Here are some pictures showing just how simple my trimmer is. It will work with any case using the same diameter brass. Build one for a 6 BR and you can use it on any case with a 0.473 casehead by adjusting the collar.
The one pictured was a 6mm BR that had a magnum reamer run into the old chamber a quarter inch past the shoulder.

[SonofWWIIDI]

????

[J-cat]

????

Too slow and cumbersome.

[MarkG35]

Is this a pole?
I like #4
Or maybe in a pinch a chopsaw.

[jeff1776]

What about a benchtop vertical bandsaw, and a jig so you could run 10 or so at a time down the fence?

[Wrangler John]

My gosh guys, you have a die set made to form the brass, right? So, if you have a trim die made you just hacksaw whatever stands above the trim die and then hit it with a file. This way the case mouth comes out square to the case body. I form .375 H&H into .375 Epstein Magnum which requires shortening the case by about 3/8", first with a 32 TPI hacksaw and then with a file, takes about 30 seconds. Same with .30 and .357 Herrett. They all come out at a consistent length.

Here's a photo of forming .30-06 into .25-06 Remington, the trim die is a full length size die by its nature, it sets the shoulder length, and all one needs do is file off the excess neck. The .375 H&H to Epstein Magnum is more dramatic but you get the idea.

[LynnJr]

Some of us are lazy and don't want to hacksaw 200 pieces of brass then file 200 pieces of brass.
By full length sizing and trimming off of the shoulder you can use a drill and get all your cases within 0.001 in minutes.
I form 6mm-06 out of Lapua 30-06 brass in a single step. Just run it through a full length die.