A question on case length

Merritt · Post by **Merritt** » Sun Jan 04, 2004 11:18 pm

Here's a question for some of you technical guys that keep real close track of things.

After stabilizing my brass I end up running my cases .006 under full spec.
The rifle shoots great. No problems.

With a uniform case length in mind, the question I have is. Have any of you ever detected any significant difference in accuracy, that you can directly attribute to just the finished final case length that you chose to use?

If the brass was uniform in every respect and did not exceed your chambers maximum length would + or - .004 been detrimental to your results?

Thanks, Merritt

krems · Post by **krems** » Mon Jan 05, 2004 1:23 am

Merritt,

I like to trim my brass anywhere from .005 - ..010" shorter than my chamber length after fireforming. I never could tell the difference in accuracy when shooting BP as it relates to case length. Of all the variables in loading I feel that case length is the least important assuming your cases are uniform in length and dimensions and w/in .020" of your max chamber length. When I talked to Kirk at the shiloh plant one day he mentioned that he trims his 45-110 brass at least .010" shorter than the chamber length.

Sounds like your rifle shoots great all ready.....

Krems

LJBass · Post by **LJBass** » Mon Jan 05, 2004 2:09 am

Merrit,
I fireform all my brass first before any trimming of any kind is done. Some of my batches of 45-70 brass have come up a little short after fire forming with no trimming at all. Once it's formed I trim it back .010" from chamber length and shoot it from there. I have found that my rifles will tolerate a case length variance of .005" to .006" with no loss of accuracy. I shoot both Swiss and Elephant in a 40-65, 45-70 and a 45-90, neck size only and religiously scrub out my case necks with a brush. If you use ceramic media you might be able to forego scrubbing out case necks, but I learned a long time ago after watching a friend trying to knock wedding rings out of his 45-90's barrel that "clean case necks are next to godliness". I have never personally had a case stretch beyond .005" or .006" over trim length (knock on wood) during it's shooting life. Hope this answers your question.
LJ

Rick Crabtree · Post by **Rick Crabtree** » Mon Jan 05, 2004 11:16 am

Grease groove bullets seem to be somewhat forgiving of case lengths. Paper patched bullets are a different matter. I prefer my case length to be no more than .005" shorter than my chamber.

Merritt · Post by **Merritt** » Tue Jan 06, 2004 12:49 am

Great replies.

Although Iv'e shooting blackpowder cartridges constantly for over thirty years my experience is somewhat thin in that it has been limited to three
rifles that I know very, very, well.

Based on those few guns my own conclusions are similar.

That case length is reletive to fit/function only and it would be highly unlikely within any given chamber to be able to assign a downrange tangible value to that feature alone.

Thanks for taking the time to share your observations.

Merritt

JAGG · Post by **JAGG** » Wed Jan 14, 2004 10:33 pm

Yes the closer the case fits the chamber length the more accurate to load ! I trimed my brass before fire forming and it came out shorter after formed ! Not as accurate now unless i full length resize which squeezes the case length longer for a better chamber seal , then it makes tighter groups ! Just what i learned the hard way ! JAGG

Merritt · Post by **Merritt** » Thu Jan 15, 2004 1:52 am

JAGG,

Now you've got me really curious about a couple of things.

1. Just how close to your chambers max is your brass when you notice the difference in accuracy come into play?
2. Are you going by the full actual chamber length?
3.How much longer than the spec. length for your cartridge is your chamber?
4. What brand of brass are you working with?
5. What cartridge were you refering to?

My brass in the 45 2.6 will shrink about .003 on the first firing. I'm using
Starline. My rifle has a real snug chamber and is a tack driver when I do my part. Nominal growth per firing is about .001 in this rifle for shots 2,3,4 and the cartridges seem to stabilize at that point. I haven't cast my chamber as yet.

I appreciate any input you want to throw my ,but it will probably provoke more questions from me.

Thanks Merritt

JAGG · Post by **JAGG** » Thu Jan 15, 2004 9:13 pm

M ! What i did was trim my 45/70 Remington cases to the lyman trim to length specs. with out first fire forming ! Dumb idea ! So on fire forming they shrunk more and way under specs ! When i FL size they lengthen and the groups tighten up again ! But i don't have the powder space with FL sizing and i like more Power ! Use a metal ruler to check your chamber length ! I bought more cases ! JAGG

Merritt · Post by **Merritt** » Thu Jan 15, 2004 11:47 pm

JAGG.

I'll bet you could pick up another 3 grains capacity with Winchester brass.
Thanks!
MJ

Ken Hartlein · Post by **Ken Hartlein** » Sun Jan 18, 2004 11:18 am

I trim my cases to 2.095 after fireforming. My Shiloh chamber measures exactely 2.10 and the 2.095 seems to work well in my rifle.