RCBS case trimmer woes.

[Yosemite Steve]

And here I am again.

I have been using my old RCBS cheapo case trimmer. As of late it has not topped other spending priorities. This trimmer will not trim 2 cases the same. The worst part is that the pilot opening the neck and leaving scratches around the inside of the neck. Am I missing something? I use the set screw to hold it in place. It sits stationary as the case turns around it. This leaves uniformity issues with my case necks. Do I let the pilot spin with the case? I then have to tighten it again to pull it out of the neck.

 

[Unclenick]

Inside neck lube will help. If you have any burrs or rim bending from hard extraction or semi-auto extraction you won't get uniform length.

 

[Paul B.]

I'm a bit confused when you say no two cases are trimmed alike. I make up a dummy round properly trimmed to set up my trimmer, an RCBS like yours. Once adjusted I make very sure the set screws are properly tightened. I use a caliper to spot check cases during the trimming period. You can even do each one right after trimming if you want but I've since not found the need.

On the pilot, even more confusion. You say the case is turning and that's causing the scratches. It's the pilot that should be turning and it seems the scratches are perfectly normal as they come from the pilot. In the 20 plus years I've used my trimmer it hasn't hurt a thing. If the shell casing itself is turning, you either do not have the proper collet or it's not being properly tightened prior to trimming. If you're getting uneven trimming, the case not being held properly with the collect could very easily be the cause.

I'll be honest here, sometimes it would be nice to be on hand to witness the problem as it happens. Most of the time that just ain't happening. Here's what I suggest.

1. Make sure you have the proper collet to hold the cartridge case.

2. Make sure the case is snug against the rear of the collet prior to snugging it down. it does not have to be super tight, just enough to keep the case from turning.

3. Make sure the set screw holding the pilot in place is tight. It's not fun if it ends up inside the shell requiring you to cut the shell open to get the piolt back. (Ask me how I know. )

Some cartridges stretch more than others, the 7x57 being a prime example. Sometimes trimming leaves a lip of sorts that had no place to go. Makes withdrawing the pilot a bit of a PITA. I've never figured a way to combat that.
Paul B.

 

[Yosemite Steve]

The collet is recessed further with more tension to hold the case from turning. Slight variances in head diameter cause more or less of a turn on the collet causing variable case lengths up to .005". As the neck turns on the collet I can visually see it expanding. And as it does it puts scratches inside the neck. If i resize to. Correct this it lengthens the case again.

 

[gwpercle]

With the older rotary trimmers a little tip that really helps is to trim them before sizing.
Everybody and their brother says to size then trim...it came with the directions of my old Pacific trimmer....but you know what...I was having the exact same problems.
On the fired case the neck opening is just the perfect size for the pilot to slide in, the case spins on it easily without scratching up the inside and the case slides off the pilot.
I had trouble getting the sized case both on and off the pilot. It was a job getting the trimmed case off the pilot.
Now to make up for trimming before sizing, just trim the fired case .001 shorter than what you want...then size the trimmed case.
This method may be unorthodox but it sure as heck works ! I been doing it this way about 40 years....rifle and handgun cases!
Gary

 

[cw308]

I trim with the RCBS Trim Pro manual , has a shell plate . I was having the same problem , I was getting a scratch about 1/8 " in from the case neck . Called RCBS the unit has a lifetime guarantee , they polished a new pilot ,sent it to me NC . How often are you trimming your brass ? As far as the brass cutting different lengths , one of the two adjustment knobs have to be loose or your brass is trimming hard your not stopping at your setting . I would call RCBS an get a new cutter an a polished piolet . Also on your sizing die , are you using the expander ball . You are cleaning your brass before sizing . Sorry ,had to ask . What makes trimming easier for me is I trim to a set size every firing whether they need it or not , just part of my case prep.Hope I Helped .

Chris

 

[Yosemite Steve]

I fixed my issue. I turned the pilot down with some emery cloth so it quit scratching the inside of the necks and widening them. The other fix is that I make a mark to line up with the collet handle so that I turn it to the same spot every time. If the case is still loose I just hold it with my fingers during the trim. Batch of 50 all within .001"