Trimming 223 too short?

J

jproaster

New member
Just a simple query: Knowing that I want to trim 223 cases to 1.750... I'm wondering if these 50 or so cases I trimmed to 1.746 is safe to load.

Thanks
John
 
jproaster said:
Just a simple query: Knowing that I want to trim 223 cases to 1.750... I'm wondering if these 50 or so cases I trimmed to 1.746 is safe to load.



Thanks

John
Click to expand...
They'll be fine. After 2-3 loadings, they'll be at 1.75" or longer.

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I initially trim mine to 1.740 so that I only have to trim once. By time they get to 1.760 it's time to put them in the "in case of hard times" bin.
 
I've been trimming mine to 1.740 for about 10 years now, never had any problems.

Also, years ago out of curiosity I measured some factory cases (Federal, Winchester, Hornady, American Eagle and a few others) and discovered that most of them measured less than 1.760 inches. Some were cut to 1.73 something, IIRC. Most were between 1.74 and 1.75 inches.
 
In the days when the M14/M1A was the standard service rifle match platform, the standard advice was not to reload a case more than four times for fear of a head separation. Because the 308 cases can stretch an average of 0.010" per firing when FL resizing M14 brass, some competitors would trim cases below SAAMI minimum by -0.020" just to avoid having to resize them again before they were ready for the scrap bucket. Nobody I know of experienced any problems following that practice.
 
Trimming a few thousandths off the case mouth does not affect safety. A case over max length can but a case with a shorter neck does not.

the listed "trim to length" is an arbitrary number, chosen more for convenience than anything else. Most cases trim to lengths are approx 0.01" below listed max, so that you don't have to trim every reloading cycle.

Some cases, have trim to lengths half that (0.005") and some even less. The .45-70 trim to length is 0.005" below max case length, and the 9mm Luger is 0.003".
Listed trim to length for the .223 is 0.01" below max case length.
Cases with necks shorter than that are fine to shoot as long as you have enough case neck to properly grip the bullet.
 
Yep, though I wouldn't call it arbitrary. The trim-to length normally targets the middle value of the SAAMI drawing's length tolerance for a cartridge case with the idea that if you miss that value it will be by ±some amount so that targeting the middle of the range protects you from errors in both directions equally.

Most rifle cartridge cases and revolver cartridge cases and some pistol cases have a SAAMI length tolerance of minus twenty thousandths from the maximum value (the one on the drawing). This is why most are trimmed ten thousandths shorter than maximum, as that's the midpoint in the range. But some pistol cases can't be that loose because they headspace on the case mouth, so you find a number of them have a tolerance of minus ten thousandths, so the trim-to is half that, or minus five thousandths.

The .223 Rem is a special case. Its length was 1.760"-0.020" in the 1992 SAAMI standard, which put the trim-to at 1.750". But that was changed to a tolerance of -0.030" in the 2015 standard, so now the expected trim-to length is 1.745". Most load manual authors have ignored the change and have stayed with 1.750". It's just so easy to remember "one-and-three-quarter inches", so why would you change?
 
I trim mine to 1.745, mainly because at that length very very few cases that I pickup are shorter to begin with. This way pretty much all my cases wind up being the same length. On average I’d say out of a 1000 cases I retrieve you would find maybe 5-10 shorter than 1.745. I know this isn’t a real big deal, but it’s the way I like to do it. To me it’s just one step in trying to make ammo as uniform as possible.
 
I normally trim mine .005 to .010 shorter than recommended to keep from trimming every time. I just go through them with a calipers & only size the ones that have exceeded the 1.750 size.
 
The 1.760" number is safe. No chamber reamer I can find a drawing for is shorter than that. Most have at least .012" of extra length in the neck (the SAAMI standard allowance), meaning they would actually be fine with 1.772" case. The only exception I find is the PTG Match reamer, which is right at 1.760", so it is not made to the SAAMI standard. If I had one of those, I would probably trim anything over about 1.758", just to allow for a couple or thousandths of measuring error that might be made if I were in a hurry. The main thing to keep in mind is that growth in the neck happens during resizing so that if the neck fits the chamber, it's good.
 
Yep. And that's how it is, provided both the case and the chamber are complying with the SAAMI standard. The extra 0.012" is then automatically built into the chamber. It is only in the instance of that PTG chamber that isn't SAAMI compliant that I saw the oddness.
 
Years ago I was watching the Super Bowl and trimming cases for my 220 Swift. In all the excitement I managed to trim the cases way too short. And it was all the cases I owned, being Norma cases and hard to find and expensive. I decided to go ahead and use them. There was never any sort of problem from the short neck cases. They lasted a very long time. I was neck sizing back then, so the cases weren’t getting overworked.
 
Some years ago I trimmed a few hundred .223 cases "too short" due to not realizing the length lock on my trimmer had slipped. Necks were very visibly short like 1/8" or so.

Every one worked exactly the same as "in spec" trim to length brass. Can't say if there was anything different in accuracy, as I don't shoot .223 for match/ varmint accuracy, my old Mini 14 doesn't care much about that. :D

Function was normal, and accuracy was normal for that rifle. No problem, other than it looked "short necked".
 
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