Case Trimming Tools and Methods Needed

[Gnnut2]

I have concerns about varying 9mm case lengths and its effect on headspace. I know that all cases should be uniform in length, but I have never been able to produce a consistent case length with the trimmers I have used. Ten to 15% of the cases will be a different length. (I’m using these percentages loosely). I have a Redding cast iron trimmer mounted securely to my bench with the collet type chuck that holds the case. The trimmer head has a hole for the case pilot which is held in place by a set screw. The cutter arm is adjusted using a set screw to slide the cutter in position once the case is fully on the pilot. Setting this thing up is imprecise in my opinion due the fact when in operation the crank arm is turned and the pressure used to trim the case will always vary a little and yield differing results. Due to repeated frustration with this tool I decided to buy the Lee hand held trimmers that have pilots made for individual calibers with their own shell holder. i sometimes get different results with these too. I think it may be a function of how aggressive I am with the rotation of the cutter, and I suspect this may be the problem for me with each of these system. If you have any suggestions I'm open to them.

Regards,
Gnnut2

[Wobbly]

First of all, you don't need to or want to trim auto pistol cases. They tend to grow shorter with each reload anyway, so all you are doing is hastening their End Of Life.

Due to the differences between roll crimp (used on revolver cartridges) and taper crimp (used on auto pistol cartridges) you really don't need extremely close case length tolerances to get consistently good taper crimps. Below is a cartoon that sort of magnifies the difference. It's not perfect, but you can hopefully see and understand how the "swagging" action of the TC simply works it's way further along the case mouth when the case is slightly longer.




Case trimmers are only used on 'bottle neck' rifle cases. Maybe the extremely short length of the 9mm case is one reason your trimmers aren't able to perform better.

Hope this helps.

[Gnnut2]

Mr. Wobbly,

Please disregard the last sentence in my previous reply regarding case length crimp. You answered it here.

Thank you,
Gnnut2

[ReloaderFred]

In 57 years of reloading, and about 55 years of loading the 9mm, I've never trimmed one.  I also expect to NEVER trim a 9x19 case, and I'm well over 850,000 rounds of loaded ammunition in 34 different calibers.

Believe me, life is too short to spend it trimming handgun brass.........!

Hope this helps.

Fred

[DWARREN]

As the others have stated I have never had to trim 9mm cases ot any other auto pistol cases.
I  have found no need so far.

[Gnnut2]

Thank you all for your responses. I will not EVER trim another straight walled pistol case!

[Wobbly]

Please disregard the last sentence in my previous reply regarding case length crimp. You answered it here.

No, sorry. We can't possibly do that. We can possibly "ignore", but never "disregard".