When do you trim?

[Fred S]

When should you check the case length and trim to size, before the case is resized or after?

Can a case expand beyond proper length in a resizing die?

Thanks

Fred

[LIProgun]

Trim cases after resizing. Rifle case often stretch during full-length resizing. The only way to be sure of the final case length is to trim after resizing. An exception to this may be if one is only neck sizing, but I'm not really sure about that.

A case can indeed strecth beyond max during sizing. I have seen it many times, especially with .223/5.56mm brass.

As a simple test, measure some rifle brass before and after resizing. Judge for yourself.

[echo3mike]

Another "after resizing" vote. I'm neck sizing brass fired in a 700 VS .308, and it seems to lengthen the cases along with full length sizing. Check the cases after sizing with your calipers and compare the measurements to data listed in your reloading manual. The trim-to lengths are there for a reason.

Of course, if you're shooting a semi-auto rifle, case stretch will be more common. You'll need to FL size with every reloading, i.e. check the length every reloading.

[DAVID NANCARROW]

Going through the whole drill, I full length resize the case, trim to minimum length, uniform the primer pockets, deburr the case mouth, and then deburr the flash hole. After firing, I neck size, which keeps the case from growing too much, and trim to minimum length once again. I do not have to trim for the next several loadings, but I full length resize every 4th firing. When I get close to max length at this point, I will trim to minimum once more and then will usually get 4 firings and its time to toss it. BTW, I think its RCBS which now offers a sizing die they claim keeps the case within SAAMI dimensions, but I have not tried it-has anyone else?

[Mal H]

Fred, you didn't specify which case/cases you are asking about. Everyone, including myself is assuming you mean when do you trim rifle cases and the members have already given excellent advice. If, however, you mean when do you trim pistol cases, I think the general consensus answer is - never. They usually don't need it and when they do, it's cheaper and easier to just toss them.

[Fred S]

:) Thanks for the replies. I asked the generic question to see if responseds came up for both pistol and rifle cases. However, my main cconcern is about rifle cases. I have been sizing them checking length with trimming if necessary. I use a Dillon 550 and this procedure breaks the progressive sequence. This months' American Rifleman Mag from the NRA has an article on rifle reloading and the author sort of alludes that he trims first before sizing. Its not clear in the article but got me thinking. I'll drive on with the way I'm doing it.

[Mal H]

Fred, I can't find the section you saw where the author (Towsley) implied he trims before resizing. The only thing I found was the picture on page 53 stating that a case is trimmed after firing and resizing.

[Fred S]

Mal H:

Dadgum it, I left the mag at work... Have to wait till tommorrow to re-read. Maybe I misunderstood something.

Fred

[DAVID NANCARROW]

I'm not certain what purpose trimming before sizing would be, expecially with new, unfired brass. If it were fired brass, you could be taking the chance at trimming at an angle as the case mouth is much larger than the caliber. Just to keep it as accurate as I can, I will trim after neck sizing because the case length grows a bit, although not nearly as much as when full length sizing is done.

[echo3mike]

Alot of shooters trim their (unfired) brass before its' first firing. Depending on the quality of brass you're buying, it's probably not a bad idea to perform a quick sample with a few cases to insure uniform case length.

If you really get anal about this stuff, you could make the intellectual leap that new cases with differing lengths will also have different weights...which can infer non-uniform case volumes, which could lead to variations in how the powder ignites which can cause differences in bullet impact which could ruin the entire world economy causing a collapse of civilization as we know it....

Sorry.

The pre-firing case trimming is something to think about, but I usually just buy really good brass to start with and go from there.

[Fred S]

The article is in the July 2001 issue of the American Rifleman, called "Centerfire Handloading." The author does not come right out and say trim before resizing but leave an impression with me that he may mean to do so (The author never says when to actually trim in the sequence).

On page 50, second column, first full paragraph, Mr. Towsley states: "Because the case is once fired it is assumed that it will not need to be trimmed for length, however, if you have a dial caliper, go ahead and confirm that your cases do not exceed the maximum length listed in the reloading manual." He then talks about ensuring the case is clean then lubed. In the next two paragraphs, he talks about resizing. He states, in the second paragraph of that column: "Resizing brings the case back to the proper outside dimensuion to ensure in will chamber easily in the chamber."

He may not have intended this, but it gives me the impression that before you lube and resize, you measure length and trim. Now many of use may take it for granted that you trim after resizing, as we are experienced. However, this article is intended for the newcomer to reloading.

Fred

[DAVID NANCARROW]

I'm not much on trimming pistol cases either, but part of my case prep includes getting every dimension as equal as I can, and trimming after firing and whether neck or full length resizing on a once fired case gets them as close to being the same as I can, therefore I do.

[Fred]

I trim after resizing. Some experimentation on my part shows a .001" to .003" case stretch after resizing with .223 brass.

[sundog]

Fred S, I've been looking at the latest AR you quoted from. I will tell you this, I have 100 new RP 6.5x55 cases on my bench right now that ALL had to be trimmed. There are no assumptions to be made about length. I've also had new 32 Win Spl cases that were over length. I've also had to trim batches of once fired brass on more than one ocassion. I sample length after sizing and trim as needed, that means that if I find even one over length they all get checked and uniformly trimmed. If what you quoted is correct, I will take exception with the author. Do not assume once fired brass is within spec. Sample your lot every time. As far as having a dial caliper, this is one of the 'need to have' items if you are reloading center fire rifle (along with safety glasses and a scale). A decent caliper is not that much $$.

btw, I noticed your "GO ARMY". I'm retired, what are you doing?

sundog
NRA Certified Reloading Instructor (Metallic and Shot Shell)

[Mal H]

I see what you mean, Fred S. He has you checking a once-fired cartridge for the proper length before he goes into the sizing steps. A novice reading that would definitely be confused. Fortunately, the picture with the trimmer is more specific but it may be overlooked.

As an interesting side note - The paragraph you mentioned is on page 51 and is the first paragraph in col 2 in my issue. I think the magazine is regionalized, so that may account for the different layouts.