6.5 PRC Case Trim Length

[Latino Texan Hunter]

I see everywhere for this cartridge you want to be between 2.010"-2.030"

What happens if I trim a few casing to 2.006"?
.004" below minimum trim length

 

[Roninco]

That should not be a big issue. The cases my lengthen with a few reloadings if the primer pockets last long enough. You may have a carbon ring develop in the throat after a hundred rounds or so. Scrub the throat well with a nylon chamber brush and carbon cleaner to mitigate the buildup.

 

[Seabeeken]

I see everywhere for this cartridge you want to be between 2.010"-2.030"

What happens if I trim a few casing to 2.006"?
.004" below minimum trim length

A larger carbon ring in the chamber for one thing. I run all mine at the max case length the chamber will allow and verify with a bore scope. When i get to the end of the chamber, I trim .005 under that length and keep em there. After all, isnt custom ammo for our particular rifle what we are striving for? I like those longer necks. YMMV

 

[Varmint Hunter]

A larger carbon ring in the chamber for one thing. I run all mine at the max case length the chamber will allow and verify with a bore scope. When i get to the end of the chamber, I trim .005 under that length and keep em there. After all, isnt custom ammo for our particular rifle what we are striving for? I like those longer necks. YMMV

This is a rather good idea.

 

[QuietTexan]

What happens if I trim a few casing to 2.006"?
.004" below minimum trim length

In general, nothing. You could probably go so short as to create problems, but you shouldn't ever need to cut that much brass off to make a case work. Flip your focus around from "how short do I make them" to "how long can I leave them".

Case length is pretty far down the list of things that matters on target, with the caveat of assuming you're starting with matched, high quality brass. The goal is to make sure you don't hit the end of the chamber. Other than that, uniformity and consistency are the only reasons to do it. IMO trimming is done way too often, and results from oversizing cases. In my experience very few cases really grow so much and so inconsistently that they need to be trimmed every firing. Cases I'm intentionally sizing small like range AR brass yes because I'm intentionally making the case small, but for good rifle brass let it grow and let it fill out before you start cutting on it.

Sinclair Chamber Length Gage

Sinclair Chamber Length Gage https://www.brownells.com/reloading/measuring-tools/case-length-gauges/sinclair-chamber-length-gage/

www.brownells.com

I would recommend you actually measure your chamber length and don't trim to an arbitrary length from a book. Use what your chamber needs, it could very well be long or short and you'd never know.

I use a borescope to confirm cases are short of the end of the chamber. I don't trim to any set length, I trim back to uniformity after cases are fully grown if the variance warrants it. Last batch of Lapua brass was all within 0.003" of each other having never been trimmed, and still short enough for my chamber. This is about when I'd go through and uniform lengths and square up the necks just because, but everything seems to be working fine for now so I probably won't bother.

 

[coop2564]

Nothing. Done it myself, they still shot and grouped very well.