Trim length tolerance?

[masan]

Hey all,

For precision shooters, what is an acceptable range of tolerance for trim length? For example, I trim 223 to 1.75 and my tolerance seems to be in the .003 range or down to 1.747. Using WFT’s btw.

Interested to hear everyone’s thoughts.

Cheers.

I compete in Short Range Benchrest, and I can tell you that as far as I and most other shooters in that particular game are concerned, the neck trim length really only matters for a few things.

1. If you are going to neck turn, your trim length needs to be identical because the neck turners index off of the case mouth. After you neck turn, it doesn't matter, so long as you...

2. Don't let the brass grow longer than the chamber.


Outside of BR there are some other factors enumerated here already by other posters.

As far as accuracy is concerned, it doesn't really matter.

[aklaunch]

The Little Crow trimmer instructions call for using your drill at high RPM. I have a corded drill that spins at close to 2000 RPM it seems. I had that same thing happen to me trying to make less noise at low speed while my kid was napping. You have to run that thing fast or shavings will collect in that shoulder area and give you variations.

NWP had a great post and covered it really.

I learned the hard way about different sizing dies set ups on my T7 a ways back.

[ubet]

I don't trim for 308 and rarely do 223. I figure I can shoot or I can worry about every minor detail down to the .0001. I'd rather shoot. But honestly, I despise reloading, even on my dillon 650.

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[markm]

I don't trim for 308 and rarely do 223.

I rarely trim .308. And I only trim .223 because I have the Giraud and it chamfers the necks. The .223 brass doesn't usually trim much off at all unless it's once fired 556 stuff that's really long. After first trim, it's maintenance/chamfer.

I figure I can shoot or I can worry about every minor detail down to the .0001.

It's definitely a balancing act. I don't do anything that doesn't actually improve the ammo. All this depends on volume too. If you only load 50 rounds per week for one bolt gun, you can go balls out and nit pick every little detail. I have too many irons in the fire to be too anal about the ammo.

[Lefty223]

Read up on RCBS X dies, by Larry Gibson, as he extended the avg case life by 3-4X using them in 7.62x51 in a Springfield M1A.

[ubet]

I rarely trim .308. And I only trim .223 because I have the Giraud and it chamfers the necks. The .223 brass doesn't usually trim much off at all unless it's once fired 556 stuff that's really long. After first trim, it's maintenance/chamfer.



It's definitely a balancing act. I don't do anything that doesn't actually improve the ammo. All this depends on volume too. If you only load 50 rounds per week for one bolt gun, you can go balls out and nit pick every little detail. I have too many irons in the fire to be too anal about the ammo.

Good to know. Your insight and common sense wisdom is priceless

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[markm]

ubet, If you get any interesting results on your crimp tests, post them up.

[ubet]

ubet, If you get any interesting results on your crimp tests, post them up.

Will do. I crimped my ocw test rounds last night. Need a break in weather and time to go try them. Then I will do a ladder test inside the node at 400yards. After I have my charge weight I will try 10 crimped vs 10 not and post.

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[Eric D.]

Skimmed the thread and not sure if anyone mentioned it but variation in your measured OAL after trimming will include variation from the sizing process as well because the WFT or similar indexes off the case shoulder. In my experience brass of different lots/headstamps/fire counts/etc will all size back a little differently, as much as 0.003” from what I’ve seen, even from the same die at the same setting. If you’re not aware of sizing variation you may have you’re chasing your tail trying to tighten up trim length variation.

[Vegas]

I’ve been using CBC brass recycled from a case of 62gr I bought a few years back. I recently picked up some Lapua 55gr loaded ammo so once I get through those, I’ll rotate those into my precision loading.