Case Trimers?

[pitandkahr]

I'm still gathering stuff and was wondering how important a case trimer is and what are the pro's and con's of the various trimers out there?

[muggsy]

Case trimmers are used to bring the OAL of the case to specs. It is important that rifle cases don't exceed mfg. specs because cases that are too long will be crimped in the chamber and this can cause excessive pressure when you discharge the round. Most pistol cases head space on the case mouth. Excessive head space can cause light primer strikes. There is usually a .010 difference between the maximum and trim to case length. I've used a Lyman Universal case trimmer for years and it has served me well.

[pitandkahr]

Case trimmers are used to bring the OAL of the case to specs. It is important that rifle cases don't exceed mfg. specs because cases that are too long will be crimped in the chamber and this can cause excessive pressure when you discharge the round. Most pistol cases head space on the case mouth. Excessive head space can cause light primer strikes. There is usually a .010 difference between the maximum and trim to case length.

So if I'm mainly loading 9mm, I more than likely won't need a case trimmer?

[muggsy]

So if I'm mainly loading 9mm, I more than likely won't need a case trimmer?

You can probably get away without one, but I generally trim all of my pistol cases to trim to length for the first reloading. The cases don't generally stretch much when fired, but then I'm a little anal when it comes to reloading. I've become very attached to my fingers and eyes and don't want to lose them.

[pitandkahr]

You can probably get away without one, but I generally trim all of my pistol cases to trim to length for the first reloading. The cases don't generally stretch much when fired, but then I'm a little anal when it comes to reloading. I've become very attached to my fingers and eyes and don't want to lose them.

Great point...What trimmer do you use and suggest?

[dkmatthews]

I don't bother trimming my pistol brass. Rifle brass, though, will definitely stretch.

Some press kits come with a trimmer. All in all, they all do the same job.

If a trimmer had not been included in my kit, I probably would have bought a Lee Zip Trim.

[MW surveyor]

FWIW - I've never trimmed cases for the 9 mm or 45 ACP. If you measure a few of the cases, they are pretty consistent. I have found some brands to be a tiny bit shorter than spec rather than longer. As long as the finished ctg will pass the plonk test, I'm happy.

I have trimmed cases for the 38 and 357 as the crimp on the case is more critical.

[bapple]

I don't bother trimming my pistol brass. Rifle brass, though, will definitely stretch.


+1

I don't trim pistol brass ever in 9, 40, or 45. I've loaded some 9mm rounds 7 or 8 times and they still function just fine. I certainly trim for .223 and for 30-06.

If you're set on getting one though, I think the easiest to use are the Lee trimmers that use the long rod. They cut all the cases to the same length and can be used with a drill to speed up the process. I use the Lee case trimmer on my drill partnered with an RCBS Trim Mate for my .223 and 30-06 case prep. The Trim Mate makes chamfering and deburring cases a breeze compared to wearing out my wrists. If you insist on trimming pistol brass, or start loading rifle brass, I highly recommend each one.

[Ken_K]

I've never trimmed any of my 9mm or 45acp brass. My brass starts to crack long before they need trimming, YMMV.

[MDIceman]

If your a rifle shooter/reloader - a case trimmer is a must. Those cases do grow, and must be trimmed to avoid bullet pinch - which can cause a dangerous spike in case pressures.

For most straightwall semi auto pistol round - it isnt as critical. However, I trim mine once - at first loading. You would be surprised at the differences in lengths of cases of different manufacters. I have found 45ACP cases at the range that were grossly out of spec. Trimming them the first time - makes sure that the cases are the same length, and headspaces equal - which makes better consistency.

Most straightwall semi auto pistol (that headspace at the mouth) cases actually shrink in time- from the case being peened by the hammer/ firing pin. This is why I only do it once for those rounds.

Revolver rounds - trimming will help give you an equal and consistent crimp tension - since they are usally rolled crimped into a cannelure.

As far as what type of trimmer - thats a personal choice. The lee style is basically a go/ no go trimmer. The pilots are set to cut the case to SAAMI specs. If the case trims - it was too long, if it dosnt - then its not too long.

I personally use a lathe style RCBS trim pro. You set the amount of trim manually. These style are used more by wildcatters -since cases that need to be step formed and fireformed - often need to be cut to a certain measurement, before forming. But it will trim any case you need to any spec you need - when using the needed pilot & shell holder plate.

[CJB]

Most pistol rounds are such that the brass does not flow - pistol brass being straight walled for the most part.

One thing a trimmer will do for you on pistol brass, and that is give you a nice square case mouth. Thats part of the anal - reloading thing, but you'd be amazed how out of square things can get.

[TominCA]

I never trim cases - most of my loads are light in 38 spl or 45 acp and haven't had trouble.

[muggsy]

I trim all of my pistol cases for the first reload. Doing so will give you a more consistent crimp and better accuracy. I use a Lyman Universal trimmer. It has served me well for over twenty years.

[AIRret]

We have a RBCS case trimer but we haven't used it yet. In fact we bought a hornady ammo plant that we haven't used yet. That's because we are still on the road and our equipment was shipped to our house a month ago.
Wish us luck, we'll be home soon.

[dkmatthews]

We have a RBCS case trimer but we haven't used it yet. In fact we bought a hornady ammo plant that we haven't used yet. That's because we are still on the road and our equipment was shipped to our house a month ago.
Wish us luck, we'll be home soon.

Best of luck. Drive safely!


Fat-fingered from my Samsung Galaxy TAB2...

[Micha2u]

I trim all of my pistol cases for the first reload. Doing so will give you a more consistent crimp and better accuracy. I use a Lyman Universal trimmer. It has served me well for over twenty years.

I also trim my pistol cases using a Lee Trimmer before the 1st reload to true things up and usually get about 15% or so that have some brass shaved off.

[rago]

with caliper when i deprime never trimmed any pistol brass yet