Trim Length Consistency

[copperking81]

What do you guys consider as acceptable variance in case length between cases? I generally trim after each firing and sizing, unless the cases haven't grown (obviously). Usually, the the variance between my shortest and longest cases (after firing / sizing) is ~.005. The other cases seem to fall along a normal distribution pattern between the shortest and longest.

I'm just wondering if I'm doing more work then needed and potentially shortening the life of the cases by trying to get each one the exact same length after every firing.

Thoughts?

 

[jimmymac]

I do not trim every time. For short range practice work, I don't get too excited about a few thousandths variation. However, if going to a match all that brass would be the same length to start with. The long range guys probably feel different.

Trimming to the same length won't shorten your case life provided you have a set dimension you trim to and never trim shorter than that.

 

[JFrank]

IMO
.005 is a bit much for variations
J

 

[hrlincoln]

What do you guys consider as acceptable variance in case length between cases?

Usually, the the variance between my shortest and longest cases (after firing / sizing) is ~.005.

I'm just wondering if I'm doing more work then needed and potentially shortening the life of the cases.

Thoughts?

Depends on the level of accuracy you need/or are trying to achieve. Never hurts to be as consistent as your equipment allows or is capable of. A variance of .005 in case length basically equates to a .005 difference in the amount of neck gripping the bullet.

 

[jackson1]

spent many years with a RCBS case trimer, the best I could hold was around 0.005". Bought a Wilson trimmer a few years ago and can now hold 0.001". Can not tell you that it is necessary but is one less thing rattling around my brain.

 

[copperking81]

Thanks guys. Yep, I have the Wilson trimmer as well and it's solid.

I don't compete but one day would like to get into F-Class. Right now I just long range punch steel and hunt but still strive to get my ammo consistent as if I were competing. Good practice and I enjoy tinkering.

 

[gunsandgunsmithing]

Thanks guys. Yep, I have the Wilson trimmer as well and it's solid.

I don't compete but one day would like to get into F-Class. Right now I just long range punch steel and hunt but still strive to get my ammo consistent as if I were competing. Good practice and I enjoy tinkering.

It can't hurt but I've never seen it matter so long as they aren't too long and are reasonably close to the same length, in SR BR. I'd be more concerned with why you are getting that much stretch, even at the extreme end, from a single firing and sizing. I have brass that may not grow that much during it's lifetime. I usually set up to trim once after the first 2-3 firings and then don't need to do it again for several more firings. It seems to stretch just a bit then stabilize for a good while afterward. I'd look at getting a sizing die that doesn't work the brass as much as yours likely is, hence creating so much stretch. Cases with a lot of taper tend to stretch more too.

 

[JRS]

You'll never notice the difference in case length that is equal to the thickness of a human hair.

 

[Toby Bradshaw]

What do you guys consider as acceptable variance in case length between cases? I generally trim after each firing and sizing, unless the cases haven't grown (obviously). Usually, the the variance between my shortest and longest cases (after firing / sizing) is ~.005. The other cases seem to fall along a normal distribution pattern between the shortest and longest.

I'm just wondering if I'm doing more work then needed and potentially shortening the life of the cases by trying to get each one the exact same length after every firing.

Thoughts?

There was a long thread on this topic awhile back. Several posts in that thread reference the 6PPC tuning videos by Jack Neary (Hall of Fame shooter). The videos are worth watching. Jack says that his testing shows that case length uniformity matters for ultimate precision. If agg-winning precision isn't what you need (or are capable of), case length variation may not matter to you at all.

 

[ireload2]

Most chambers are .020 to .040 longer than the trim length.
Unless you are some mental OCD competitor type trimming does not get you much benefit unless your cases stretch out of square.
I let mine stretch until they are chamber length or until uneven. Before a minimum trim.

 

[Richard Coody]

i never trim until necessary and then only trim halfway between max and min. have found that shoulder angle has a lot to do with neck growth. i have some improved cases with 40 degree shoulders that never need triming for the life of the case.

that said i always trim in batches. want the cases in a group to have the same neck length.

have a PMA trimmer that indexes off the shoulder. i have very consistent shoulder bumps and get very consistent neck lengths. consistent pressure on the trimmer is the trick. you can screw it up real easy with any trimmer by varying the pressure.

 

[Steve Donlon]

If you crimp it matters or like I just found out, if you turn your brass it could matter. If you use the stop on the turning tool. I guess most guys can do it my sight, that would make it easier. Because of that I keep mine at .001"-.002" as best I can.

 

[JFrank]

Has anyone tried the small quick trimmer I think it's by PMA
J

 

[bsekf]

IMHO I think squaring the case mouth is as important as exact length. I anneal about every 4th reloading and then trim to square the case mouth and get the length uniform.

Bill

 

[Dusty Stevens]

Has anyone tried the small quick trimmer I think it's by PMA
J

Yes. Works fine.

 

[JimSC]

I have no idea how much of a variation is acceptable but I trim after every resizing. I buy used Wilson trimmers and have one permanently adjusted for each cartridge I load for. Using a power adapter it takes about 15 minutes or so to trim 50 cases. I doubt my skills are honed enough for it to make a difference but if it saves me one point in a match it was worth the 15 minutes.

 

[Richard Coody]

IMHO I think squaring the case mouth is as important as exact length. I anneal about every 4th reloading and then trim to square the case mouth and get the length uniform.

Bill

i anneal every sizing.
after sizing i remove lube, measure overall length and trim if necessary, examine case carefully, run a wilson depriming pin through the flash hole to ensure it is clear, clean primer pocket with hand tool, brush out the neck lightly with a nylon brush and do a very light chamfer with a hand tool.

then prime.

 

[LGKLAS]

I can't answer your question. I only reload for my 6.5CM and use a Wilson trimmer. Which I set to a 'trim to' length of 1.918" (6.5CM range is 1.90-1.92). I trim after each firing and use a case checker. I run them all thru the trimmer and some get shaved and some do not. My case lengths are all at 1.918" or .001 to .002 shorter. If I had a .005" difference I would do something different to get them within 1 to 2 thousandths of each other. What difference does it make? I don't know.

 

[copperking81]

I have no idea how much of a variation is acceptable but I trim after every resizing. I buy used Wilson trimmers and have one permanently adjusted for each cartridge I load for. Using a power adapter it takes about 15 minutes or so to trim 50 cases. I doubt my skills are honed enough for it to make a difference but if it saves me one point in a match it was worth the 15 minutes.

It is sort of a pain dialing in the trimmer. Never thought of getting one for each caliber and leaving them dialed in. And just when I thought I finally had all the tools I need.

Its an expensive hobby

 

[Texas10]

I use the Worlds Cheapest Trimmer, as well as the Worlds Finest Trimmer. Both use the shoulder as the datum for the cutter, which is exactly how the round chambers, so you can set your trimmer to fill the chamber neck without the risk of pinching a bullet. This can help prevent formation of a carbon ring at the start of the leade.

I can do 100 neck trimming ops in about 5-6 minutes, faster than I can chamfer. I mount it in drill press or electric screwdriver and have at it.

At about $20 each for the WCT, I have one for each caliber. They even made one special for me when I needed a 338LM trimmer.

http://www.newhighpower.com/brass-trimmers.html