Overall Case Length?

[PennsyPlinker]

I forgot to ask. How critical is the overall case length, and what kind of variance is acceptable?

Thanks.

[Lycanthrope]

Overall length of a loaded case.....or just the casing?

Casings stretch with shooting and you may need to trim them depending on the caliber. I trim rifle casings, but it's not necessary with my pistol calibers.

Now..on to the OAL of fully loaded cases. OAL plays a large role in pressure (seating bullets deeper increases pressure), feeding reliability (varies from gun to gun), magazine reliability (loading longer can help to keep the rounds consistent in some magazines) and accuracy (many rifles shoot tighter groups when loaded to max OAL).

In rifles, I load as close to the lands as posssible for accuracy. In the AR, it's as long as the magazine will allow.

In semi-auto pistols I load a dummy round (no primer or powder) and start just above max listed OAL and hand cycle as slow as possible. I then seat teh bullet slightly shorter and hand cycle again...taking notes as to whether I can stall the round on the feedramp. Eventually, you find a length that feeds with very little friction and you cannot stall on the ramp.

BUT......be advised that is your OAL is shorter than what is listed for your loadings that your pressure will increase. Please reduce your powder charges and work up accordingly.

Lycananditchangesalloveragainforanotherbulletthrop e

[PennsyPlinker]

I am asking about the OAL of the loaded cartridge. I loaded 40 rounds today and got a variance of 0.002" from the ideal on some of them, all of them longer. For what I do professionally, that is non-existent. Some of the engineers I encounter think otherwise, but what do they know? I live in the realm of wood, where a difference of 1/16" is usually not a problem.

I am wondering how much of a variance I can tolerate before I have to be concerned with the process.

[SteveWag]

0.002” is pretty good. Most match bullets don’t hold that. Remember that the bullets are not seated by pressing on the tip of the bullet, but by a seater that contacts the bullet somewhere on the ogive. A slight difference in diameter or slope can easily yield 0.002”.
Steve

[Lycanthrope]

0.002” is pretty good. Most match bullets don’t hold that. Remember that the bullets are not seated by pressing on the tip of the bullet, but by a seater that contacts the bullet somewhere on the ogive. A slight difference in diameter or slope can easily yield 0.002”.
Steve

Agreed. Go shooting.

Lycangoodluckthrope

[PennsyPlinker]

Thanks guys. I'd rather ask that be the source of a story on the web because of a kaboom!

[Karys]

Right now I'm only loading semi auto pistol rounds. I started each load about 0.010" from the max OAL and I get a max variability of +/- 0.005" with Dillon dies on my RL550B. I've never had any reliabilty or accuracy issues, but I'm mostly shooting Glocks. Something with a tighter chamber may not work as well with rounds loaded that long. YMMV.

[LastManOut]

Agreed. Go shooting.

Lycangoodluckthrope

I told you so. Good idea to ask. I was wondering myself.