Home Forums Hunting & Shooting Ask The Gunwriters Case Trim Length

Reloading manuals recommend trimming cases to 0.01" shorter than maximum overall length specifications. Is there anything wrong with trimming them shorter? That way you don't have to trim them as often.

I shoot a 6XC. Norma cases are made to the maximum length and need trimmed a lot. Fireformed cases, made from 22-250 cases necked out with shoulder set back and then fireformed, come out shorter, and after 10 realoads, have not stretched to where they need trimming.

Not as long as they are the same length and there is enough neck to hold the bullet correctly.

I trim mine a bit shorter, seems to be OK

Assuming all are all less than maximum, why do they have to be the exact same length?

M Bell

General rule of thumb is to trim all cases of a particular cartridge to the same length. More case neck grippin' the bullet and less case neck length grippin' the bullet.......not much uniformity in that. Could it make a huge difference.....probably not. But if a load is a skosh under your expectations, it is nice to know that one more variable has been accounted for and your search need not generally include your cartridges case neck length factor.

As to the "too short" inquiry...........another rule of thumb is that your case neck shouldn't be any shorter than the diameter of the bullet your usin'. Recoil, a loose fittin' bullet in your cartridge case neck (for whatever reason)....all can lead to your cartridge's OAL lenghtening upon firing. Not a good thing for several obvious reasons and can actually be unsafe as well. Many a hunt has been ruined by such occurances.

Uniformity, trimmin' all case necks back to minimum book standards....a prudent approach. After 3 firings or so, most cases seem to be all "grown out" and then you'll seldom need to trim.............IMHE.

Good luck.

Good explanation!

Magnumb,

If we were talking bench-rest accuracy here, I suppose your comments regarding exact case length might be valid; however, in regards to general big game and varmint hunting, I have my doubts.

I shoot a lot of varmints, like accuracy in the .75" range (or less) from the rifles I use for this purpose, and really have no problem getting this level of accuracy without worrying about exact case length. My normal procedure when loading a batch of ammo is to set my caliper at the maximum over-all case length and use it as a gauge. If a case slips through it's OK to load and, if not, it gets trimmed approximately .01".

Perhaps I'm just a sloppy handloader, but just the thought of having all cases, the exact same length, every time they are loaded, almost gives me a headache! Besides that, I would much sooner spend my time shooting prairie dogs than trimming cases!

M Bell

Wait till you load cartridges that require a crimp.

ding !ding !ding! ding! ding!

The Lee Factory crimp die helps a lot with this. I still trim the whole batch when the first one reaches max length, and throw the whole bunch away on the 4th trim, which is what I do with cases not requiring a crimp.

Case trimming is my most-disliked operation in handloading. The Lee die helps with that, and the rifles in question (an M94 Winchester and a Marlin GG) don't seem to mind.

They don't HAVE to be trimmed to the same length but consistency sure won't hurt accuracy.

I would guess I was loading cartridges that require a crimp before you were out of diapers! I know how to be sure all cases are the same length so they can be crimped properly, but that really has nothing to do with this thread. If cases NEED to be trimmed I am all for it, but in my experience, NEEDLESS trimming (all cases every time, cases already shorter than maximum, etc.) is a waste of time! But then, I don't shoot bench-rest any more than I use cartridges that need a crimp to shoot prairie dogs!

M Bell

There are more than a few 300 Savages and Win. mags violating that rule of thumb every day.

I trim new ones about .005 shorter than the book says, then when they need trimming again, pass them on to someone else.

I found out long ago that one of the great benefits from using Lee collett dies is that cases can be used a lot more before they grow too much.


Poster: mathman
Subject: Re: Case Trim Length

Quote:
another rule of thumb is that your case neck shouldn't be any shorter than the diameter of the bullet your usin'.


There are more than a few 300 Savages and Win. mags violating that rule of thumb every day.

I trim to the loading manual recommendations. Not innovative, but it works.

From reading all these posts, I get the impression that if you have adequate neck length (whatever that is), there would be no problem in trimming shorter. For instance you could probably trim a 30-06 to .01, .02, .03, or .04 inches shorter than maximum and have no problems. Why not trim only once in the lifetime of each case?

Exactly!

Indy,

I think it will work, if you choose to do it. When I was growing up in the 50's, my uncle hand-loaded for a .270 Win., and he used mostly 30-06 brass because it was more available and arsenal brass was much cheaper. This resulted in .270 cases that were about .10" shorter than standard, but he claimed they produced groups as good as regular .270 cases and had the added benefit of never having to be trimmed.

I also remember my father (a gunsmith by avocation) experimenting with .22/250 cases of various lengths less than normal (some radically so) to see what effect this had on accuracy. He did not observe much difference.

Personally, I like to trim cases to approximately .01" less than maximum after they reach maximum length. I have always shied away from overly short cases because I'm not sure they are the best thing for the neck-throat area of a chamber. Perhaps there would be nothing harmful, but I see no reason to chance it.

M Bell

Exactly. My concern would be the neck throat-area. But what could go wrong with .02 vs. .01 inches? You're still going to ream out the rifling the more shots you fire, and the rifle will shoot pretty well after a heckuva lot of rifling, compared with .02" of slightly wider freebore, disappears.

The only downside to trimming cases much more than .010 shorter than the chamber length is the additional powder fouling and hard baked carbon deposits that will form in the area between the end of the case and the end of the neck length area of the chamber.

Depending on the case capacity, type of powder used, how often you clean, etc., it may or may not become a big deal. I like to run all my cases .020 shorter than the chamber length. But I do pay a bit more attention to this area by using some JB on a patch wrapped around a worn out brush and twisting it in that area occasionally. Works great. Iosso on a nylon brush with no patch also works fine.

One other thing: don't assume that your chamber is the exact length it's supposed to be. You can check the chamber length by seating a flat based bullet backwards and closing the bolt. The base of the bullet will jam against the end of the chamber giving you the chamber length. If you have a Stoney Point tool, you can do the same thing with this.

It's not unusual to find .020 more chamber length that your chamber is supposed to have in factory chambers.