Trimming cases a smidge too short

[frayluisfan]

Hi, all.

Recently got through trimming some .308 brass, and 10-12 cases came out just a bit too short: 1.980 instead of 2.005. Manuals I have here stress the problems of cases that are too long, but none seem to address cases that are too short. Would these cases be a concern for accuracy or safety?

Thanks for your thoughts,
frayluisfan

 

[esheato]

.025" isn't a smidge.

I would segregate them and use them as a last resort.

 

[twofifty]

Lyman's #48 specs 308Win case length at 2.015",
so that puts you .035" short of SAAMI.

That leaves approximately .269" of neck into which to seat a .308" bullet.
Rule of thumb is to have a caliber's worth of neck in which to securely seat a bullet. In Lyman's, the SAAMI specs call for .304" of neck length for the 308Win. But SAAMI specs have +/- tolerances...and I don't know what they are.

If you're loading this for a semi-auto rifle, I'd say don't bother - those necks are too short and the bullet will not be stable enough.

If loading for a bolt or lever the chambering stresses on the round are not as violent, so you're probably ok.


edit: The real danger lies in having cases that are too long. As you learned from reading your manual, cases stretch with each reload cycle. Eventually they need trimming. A too-long case's neck combined with a short-leade or short-throated chamber can end up not having enough room to expand and release the bullet. Pressures then spike dangerously.

Others with more experience will chime in tomorrow.

 

[Grumulkin]

They should be safe to shoot though accuracy may suffer.

 

[Walkalong]

Yep, safe, but may not shoot as well, and certainly not the same. Next time just be more careful.

10-12 out of how many? 200? toss the 12. 20? Dang.

 

[USSR]

Lyman's #48 specs 308Win case length at 2.015",
so that puts you .035" short of SAAMI.

The 2.015" figure is the longest allowable length, and once it reaches or exceeds that length, it is to be trimmed back to as much as 2.005". Being trimmed to shorter than 2.005" won't cause any problems, but with the .308 having a short neck to begin with, it won't be doing you any favors.

Don

 

[jmorris]

.025" isn't a smidge.

Why I clicked in here, to a carpender 1/8" is a smidge.

I'm with the others safe but not what you want.

 

[243winxb]

SAAMI Shortest Trim Length for 308 Win. is 1.995"

SAAMI is OK with as short as 1.995" on there cartridge drawings. Anything shorter, your on* your own. http://www.saami.org/specifications_and_information/index.cfm?page=CC Standard trim to length is 2.005" This subject was just covered a week or so ago.

 

[918v]

They will shoot well. Case neck length does not affect accuracy.

 

[kingcheese]

i wouldnt count on them being safe if you already use maximum loads, you are effectivly changing the volume of your case, and by having less case volume you are increasing preasure, it may or may not be a problem

 

[Funshooter45]

i wouldnt count on them being safe if you already use maximum loads, you are effectivly changing the volume of your case, and by having less case volume you are increasing preasure, it may or may not be a problem

Actually, no, you are not changning the volume of the case. By trimming too much off the mouth, it only affects the amount of neck that is gripping the bullet. The OAL remains the same, the case volume that the powder occupies is the same. I concur that they are safe. The accuracy may or may not be affected. And if you repeatedly chambered them and unchambered them as in a hunting situation, the bullet m ight get shoved further into the case at some point. Shooting them at the range one at a time in a bolt action rifle should be safe.

 

[gearjammer-2000]

shoot em, the neck will stretch and then the next reolads will be back into spec

 

[chrt396]

Ya know...I had the same question a couple weeks ago. I asked the guy that gave me a lesson on reloading and he said to throw them away! I did!! I could never understand why..and he really couldn't explain..why! I threw away 30-45 cases that I could have kept. That sucks! Well..this is all part of the learning process I guess!

 

[243winxb]

Collapsed Shoulder

Short necks.

I could never understand why..

The neck expands to seal the chamber, so gas does not get into the body area. This can happen when using very slow burning powder, mostly in magnum cases.

 

[frayluisfan]

Thanks to all for your replies. If it helps, I am firing this batch of ammo in an FNAR semi-auto .308, and I am about the mid-point of the acceptable powder range, according to the Hodgdon website...in other words, nowhere near the red line. To be specific, a 180gr Speer Hot-Cor with 43.6 grains of Varget (Hodgdon says 41-45 grains). I wouldn't mind if accuracy isn't all that great--this ammo is for cheap practice fodder. But a potential safety hazard is another matter entirely.

Thanks again,
frayluisfan

 

[gamestalker]

If your using a something other than an auto loader you'll be OK. But don't be surprised if performance is in the trash can. I did the same thing with .270 win. some years back and they were fine in the pressure dept. but didn't perform very consistently, and were well below the velocity of the other rounds of same powder charge and OAL.

 

[918v]

Really? You cut them .025" too short and it affected velocity? Please!

 

[fguffey]

30 Gibbs neck length .217, my Gibbs neck length .252. 300 Win Mag neck length .264, I choose to use the case to cover the chamber all the way but just short of the beginning of the throat.

F. Guffey

 

[fguffey]

then there is 'no choice' as when forming cases for wildcats or when forming 338/06 and 35 Whelen cases using 30/06 cases, legend (local belief) has it cases stretch when fire forming, not my cases, could be caused by my magic firing pin but my cases shorten from .030 to .045 thousands, or? it could be a local phenomena.

When forming I use the longest case available, more times than not the best choice is the 280 Remington with the additional .41 thousands case length and the .051 thousands additional case length between the case head and shoulder.

F. Guffey

 

[Ruger GP100 fan]

Are you sure you didn't misprint the "too short" cases? Could they have been 1.998? But,then,I use Lee's hand trimmer and it would be next to impossible to trim one .025 too short.

 

[frayluisfan]

Hi, RugerGP100 fan.

No, I went back and remeasured all those cases. The ones I boofered are 1.980-1.983.

Not sure what I did. I set the thing up one day, trimmed a few cases, checked those ones, and they were fine. Came back next day, trimmed a few, checked 'em, and the whole 16 that 2nd day were all short. I checked the trimmer adjustment, and the lock screws on the trimmer were tight, no play at all. I readjusted the trimmer to trim to 2.005, ran through some more, and everything went peachy.

I'm convinced some ex-KGB guys slipped in quietly in the middle of the night, and messed with my trimmer. How they got past my dog, who sleeps 3 feet from the trimmer, is a mystery. They must be really good!

Thanks again,
frayluisfan

 

[Ruger GP100 fan]

Just a good thing it wasn't powder and you were reloading. I always recalibrate my 2 scales if I leave the reloading bench for any reason. KGB or Murphy slips right in there and messes with things when I'm gone. That was one of the very first posts I read when I found THR and I abide by it to the letter of the law. That's a big change. Wonder what really happened to your trimmer?
I'm guessing 308 brass ain't cheap.

 

[helotaxi]

What case trimmer are you using?

BTW, the min SAAMI length is 0.010" shorter than the trim to length. You're somehow more than 0.010" shorter than that.

 

[FROGO207]

My bet is the case trimmer head collet sizer allowed the brass to align on the next smaller size step getting you closer to the cutter head. Then you cut X thousands more off the case neck. Happened to me once with a RCBS trimmer. Now I check each time I use it. I prefer the Lee type of length cutter used in a drill press. That's a bummer for sure.:banghead:

 

[NCsmitty]

As long as you don't crimp, and the neck tension on the bullet is sufficient, you will see little difference in down range performance.
You may get a little carbon build up with the short cases in the end of the chamber, but if you mix with your normal cartridges when shooting, it should not be a problem.



NCsmitty