I didn't want to derail the other reloading thread, but I noticed several posters recommend trimming rifle brass after sizing (neck or FL).

I am conflicted on this. I own 2 manual trimmers (Reading & Forster). Each uses a caliber-specific mandrel to pilot the case and ensure the cut is flat and not angled. I understand why one would trim after sizing- the sizing process stretches the case a little (before and after measurements show a delta). Trimming after the sizing gives a more repeatable length over the entire batch.

I also noticed I would have to force the freshly sized brass onto my mandrel and then spin a few revolutions to trim. The cartridge is now much easier to extract from the mandrel than chucking it up because I have stretched and manipulated the neck ID a little with the spinning. Some cartridges require 2-3 spins, others 5-6 spins, etc, so now I have more part to part variations in the ID dimension.

My thinking is that trimming prior to sizing may increase variations in brass length, but more repeatable neck tension. Granted, a loose fit on the mandrel introduces some 'wobble' into the cut, which may be a factor.

From what I have gleaned from some reloading forums, they seem to spend a lot of time fussing over the ID/OD of that neck and the tension it imparts on the projectile. Trimming after sizing would give a more repeatable neck tension.

For what it's worth, I have tried both and couldn't prove definitively one is better than the other. I am just curious if anyone else has chased this rabbit down the hole and what they found at the bottom?

Are you reloading hunting ammo?

Not in particular. I am working to develop the most accurate load possible for a particular rifle. I want to hold as many variables of the load constant while I test others. Hold the geometry of the brass constant while I play with powder qty and seating depth.

Can you trim pre and post sizing?

That's a helluva rabbit to chase considering all the other variables that come into play when shooting the load.

I'd stop chasing the rabbit. But I like to shoot more than I like to tinker with ammo.

You might look at getting a Wilson Ultimate Stainless Trimmer. It's the best trimmer I've ever used for precision loads. It does not use a mandrel to align the case. Instead, the brass is held in a stainless steel tube that is cut like a tight rifle chamber. The mic adjustment is very nice and repeatable too.

aggie_2010 said:

---

You might look at getting a Wilson Ultimate Stainless Trimmer. It's the best trimmer I've ever used for precision loads. It does not use a mandrel to align the case. Instead, the brass is held in a stainless steel tube that is cut like a tight rifle chamber. The mic adjustment is very nice and repeatable too.

---

This is the trimmer to buy. The mic is a must. You have to make sure you have the right shell holders, they have for new and fired. I've had the others and they are not in same league.

I body size new brass, neck size (bushing), fire, bump shoulder back .002, neck size, then trim

Tinkering with ammo causes me to shoot more.

And yes, to your point, there's more holes than Swiss cheese in this hobby, I just want to find the best practice and move on to the next challenge.

Boots over Delaware said:

---

Tinkering with ammo causes me to shoot more.

And yes, to your point, there's more holes than Swiss cheese in this hobby, I just want to find the best practice and move on to the next challenge.

---

From my experience good brass and good equipment go a long way. For me, the tolerances of the loads are almost as important as how it shoot once you get into it.

Check out www.21stcenturyshooting.com - they build some amazing stuff

Thanks Aggie2010, Slam. If I may ask, how are you determining what size neck bushing to use? Does your rifle chamber determine that?

Check out the link below about neck bushing size selection. I tend to adopt a lot of this guy's practices. His website and YouTube channel have some good info. He's a serious long range shooter/reloader, and his results show that he's doing something right. Wish I had the same toys and access to land that he does.

I use .001" of neck tension, but haven't tried anything else.

http://panhandleprecision.com/redding-bushing-dies-select-proper-bushing/

I try to use .0015 maybe more if you are seating into lands. Not enough neck tension can cause chambered round to leave bullet in lands when you unchamber. A lot of people shoot for .002 for hunting.

I just trim after. You are talking about variables that make such a small impact on accuracy that it's, to me anyway, simply not worth spending the amount of time on it due to the low rewards. Repeatability is more important than .005" in the dimension of your case neck.