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Case trimmers - need help understanding the pros and cons

Mc Fraser

Hello,

I am in the market for a new trimmer that can chamfer and deburr as well, but I need help with advice. Speed is not important for me as I do a very low volume, accuracy and consistency are very dear to me, and my rifle :)

First I don't understand the pros and cons between trimmers that trim based on total case length and the ones that index on case shoulder? Please educate me.

I currently have a Lyman universal trimmer, it is fairly accurate, however, I don't like it because it leaves marks on the inside of the neck. My smith manufactured a cross over for an RCBS 3 way trimmer head, same results leave marks on the inside of the neck. It's not the trimmer wabbling, I check it with a XXI concentricity gauge.

Let me know what your thoughts and advice are ...

TIA
 
Mc Fraser said:
Hello,

I am in the market for a new trimmer that can chamfer and deburr as well, but I need help with advice. Speed is not important for me as I do a very low volume, accuracy and consistency are very dear to me, and my rifle :)

First I don't understand the pros and cons between trimmers that trim based on total case length and the ones that index on case shoulder? Please educate me.

I currently have a Lyman universal trimmer, it is fairly accurate, however, I don't like it because it leaves marks on the inside of the neck. My smith manufactured a cross over for an RCBS 3 way trimmer head, same results leave marks on the inside of the neck. It's not the trimmer wabbling, I check it with a XXI concentricity gauge.

Let me know what your thoughts and advice are ...

TIA
Click to expand...

When you trim from the base to it's total case length, the surface of the mouth will be square to how it's held at the base, which means that very often, it's not square to the neck. Also, when trimming this way, there can be some variance in the distance from the neck to the case mouth when will show up when trimming this way. I initially started trimming with a Wilson trimmer over the other's that don't use the base of the case to trim from as I wanted a case mouth square to the case body, which should be square to the neck if the die working well. I want my case mouth to be as square to the neck as possible.

While I really like my Wilson trimmer, it was just too slow a process for me and had to deal with the chamfering and deburring process as well. Then I found the Giraud trimmer which trims 3 ways at once from the shoulder. When a case us sized properly, the should is pretty square to the case mouth and so I get a square case mouth to the neck along with a square chamfer at the same time . . . AND it's so fast, the processes is almost a pleasure. If one not doing a lot trimming and to only one or two calibers, then the Giraud Tri-Way is a good tool to consider. Of course the one caveat I'd point out here is that one needs to be sure they're getting consistent headspace results when sizing for using the shoulder as the point of measurement. If one can't do then, then . . .???
 
The caliber in question is 300 PRC (custom build), Forster or Redding competition dies and Forster Co-Ax press.
I looked Giraud, I don't think they offer their product for 300 PRC brass ...
 
Mc Fraser said:
The caliber in question is 300 PRC (custom build), Forster or Redding competition dies and Forster Co-Ax press.
I looked Giraud, I don't think they offer their product for 300 PRC brass ...
Click to expand...

Call Doug Giraud, see what he says. His website does not list all the calibers he offers.
 
Straightshooter1 said:
When you trim from the base to it's total case length, the surface of the mouth will be square to how it's held at the base, which means that very often, it's not square to the neck. Also, when trimming this way, there can be some variance in the distance from the neck to the case mouth when will show up when trimming this way. I initially started trimming with a Wilson trimmer over the other's that don't use the base of the case to trim from as I wanted a case mouth square to the case body, which should be square to the neck if the die working well. I want my case mouth to be as square to the neck as possible.
Click to expand...

If you own a Wilson yoou should know it is not held at the base. The Wilson case holder holds the case similar and it is similar to a sizing die. The case holder rides on two steel rods in the base of the assembly, that case is held tight, I keep a small piece of wood or teflon on the bench to tap the case into and out of the case holder it is so snug. The adjustable foot just indexes the distance from the cutter. I full length size my cases before I trim and when sizing the brass flows to the neck. If your sizing is done right the datum to case head distance on the sized cases should be consistent. If it isn't you need to evaluate your sizing procedure. I agree that operating one manually is slow, the power adapter is around ten bucks at Brownells and a cordless drill or electric screwdriver is a must have
 
A Giraud holds a tight tolerance case to case, and does all 3 steps at the same time very fast. The con is, it’s is expensive but worth it to me if your doing lots of calibers and cases. I simply don’t have time to do it any other way.

The Single Giraud Triways that does only one caliber the go in a drill or drill press look nice of your only doing one caliber. If your doing multiple calibers, it can get expensive this way. This one is not to be confused with the bigger unit

https://giraudtool.com/giraud-tri-way-trimmer.html

I have heard these are good to, but have never seen or tried one. 1/3 price of Giraud and you can change calibers

https://www.blackwidowshooters.com/trim-it?page=5

Wilson’s hold tight tolerances, will take way longer than the others. You will still need to chamfer and debure. As the last person said, you will need to make sure your cases are size and head spaced perfectly to have consistent trim lengths. Wilson does not trim off the shoulder like the Giraud, instead off the oal
 
Last edited:
Mc Fraser said:
The caliber in question is 300 PRC (custom build), Forster or Redding competition dies and Forster Co-Ax press.
I looked Giraud, I don't think they offer their product for 300 PRC brass ...
Click to expand...
You can have a custom shell holder made. Giraud sells a blank for wildcats and a gunsmith with the reamer can make it for you. Most of these are small company’s and are accommodating about customizing if you call them and ask
 
Last edited:
X-47B said:
You can have a custom shell holder made. Giraud sells a blank for wildcats and a gunsmith with the reamer can make it for you. Most of these are small company’s and are accommodating about customizing if you call them and ask
Click to expand...
Only for the power trimmer, you can't get a blank for the 3 way trimmer. I live in Canada, the difference in price is over $500, as great as the product is I can't justify a price diff like that for only one caliber. I asked if they have plans to make a 3 way trimmer for 300 PRC or if I can pay extra to do it for me and the answer was nope.

I'll look into black widow one.
 
X-47B said:
I have heard these are good to, but have never seen or tried one. 1/3 price of Giraud and you can change calibers

https://www.blackwidowshooters.com/trim-it?page=5

Wilson’s hold tight tolerances, will take way longer than the others. You will still need to chamfer and debure. As the last person said, you will need to make sure your cases are size and head spaced perfectly to have consistent trim lengths. Wilson does not trim off the shoulder like the Giraud, instead off the oal
Click to expand...

https://www.calguns.net/calgunforum/showthread.php?t=997473

Doesn't look like a great one.
 
Little Crow Gunworks makes the WFT2 and lists an insert for the 300 PRC. The WFT (worlds finest trimmer) trims off the case shoulder. It doesn't chamfer or deburr but it makes a very clean cut using an endmill for a cutter.
 
If speed/volume is not an issue I would get the Forster three way trimmer. You can power it with a cordless drill and it cuts precisely and is pretty fast. I use a Giraud but speed is important as I usually run 150+ per batch. I've watched a friend trim with his Forster and he is almost as fast as the Giraud.
 
Mc Fraser,
Trimming with a 3 way tool accomplishes a couple of important things.
Trim the length, chamfer the inside of the case mouth, and deburr the outside.

1st, cases with shoulders less than 40 degrees are known to grow in length.
If left unchecked, it is possible to become long enough to get pinched by the throat at the end of the chamber causing high pressure. Rare but potentially explosive.

2nd, chamfering and deburring make the neck a happy launch pad for your bullets.
Keeping the case mouth clean and smooth helps with consistency.

3rd, While different trim lengths will work as long as they aren't too long,
it is a good idea to pick a length and keep your brass at that length for consistency.

Whether you use a Giraud or a Forster with 3 way cutter,
your goal is to have your brass consistent and your bullets seating without any damage.

Based on your case volume, a Forster with 3 way cutter would certainly work.
After you watch someone use their Giraud, you might get envious.

As for your question about indexing from the case head or shoulder.
Indexing from the case head is an objective measurement that will keep your case lengths consistent. Indexing from the shoulder is a convenient way to save time and since the chances of case growth behind the shoulder are less, generally works out.

One advantage of indexing off the shoulder would be cases of different length but identical shoulder & neck dimensions could be trimmed without changing the settings. For example, it is possible to trim 6SLR and 6XC with a giraud "if you chose to".

The obvious benefit is quickly inserting and removing the case without having to chuck up the entire case the way you do in a Forster trimmer.
 
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I have the Forster power trimmer set up in a drill press and all of their 3-way cutters. It works very well and once set up I can do about 600 per hour. The Forster original trimmer also works well with the 3-way cutters.
 
I guess I'm a reloading Neanderthal, but I use the super-simple, super-inexpensive Lee tool. I started out years ago with the Forster case trimmer (not the 3-way version), but wondered about repeatability of the collet grasp of the case head. It seemed to me that very slight variations could occur when closing the collet on a case head with the result being slight variations in trimmed case lengths. I tested this out by carefully measuring a number of trimmed cases and did notice very-slight variations in resulting lengths. So I went to the uber-simple Lee tool which uses a shell holder along with a pilot that contacts the shell holder through the flashhole. Obviously indexes off the case head. I get identical case lengths when trimmed this way. You could use a cordless screwdriver or drill, but I've never bothered. You only need one cutter and shell holder (for the same size case head), with the pilot (< $10) unique to each cartridge.

ZtbqXKe.jpg


Probably far too primitive for the sophisticated folks on this forum....;)
 
South Pender said:
I guess I'm a reloading Neanderthal, but I use the super-simple, super-inexpensive Lee tool. I started out years ago with the Forster case trimmer (not the 3-way version), but wondered about repeatability of the collet grasp of the case head. It seemed to me that very slight variations could occur when closing the collet on a case head with the result being slight variations in trimmed case lengths. I tested this out by carefully measuring a number of trimmed cases and did notice very-slight variations in resulting lengths. So I went to the uber-simple Lee tool which uses a shell holder along with a pilot that contacts the shell holder through the flashhole. Obviously indexes off the case head. I get identical case lengths when trimmed this way. You could use a cordless screwdriver or drill, but I've never bothered. You only need one cutter and shell holder (for the same size case head), with the pilot (< $10) unique to each cartridge.

ZtbqXKe.jpg


Probably far too primitive for the sophisticated folks on this forum....;)
Click to expand...
I started out with the lee style, and ive thought about going back to them at times for some things. I always wondered if using them with a drill would wear the little pin and change your trim length. guess id measure them to start. for something youre not doing many of seems like they would be a good idea.
 
Giraud trimmer instructions-

Tips, Tricks & Special Requests
Flipping the trimmer vertical allows you to let the brass shavings naturally drop
away from the cutter and shell holder. If you use the trimmer horizontally,
eventually you will get shavings inside the case holder. With shavings in the
case holder, the index for the case shoulder is no longer true. Your cases will
come out longer by the same length the shavings prevent the case from entering
the case holder.
Click to expand...

Check trim length AFTER trimming.
 
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