Do you trim fired brass

[TheSilverFox]

If you do so, why would you trim brass after it has been trimmed once when it was new?

 

[memilanuk]

Because 1) it may reach the listed 'max' length long before the useful case life is used up. i.e. if one is getting 20-25 firings out of a case, you're not going to never trim again just because you did it once when the cases were still virgin? and 2) some people want to keep the case lengths the same because it makes them feel better or they believe it helps on the target.

 

[Twud]

I assume we're talking about trimming and not turning.
It it's trimming, the brass flows forward to the neck when firing. If you don't trim the case would eventually become too long for the chamber. Most also feel that a consistent neck length contributes to accurancy.
Mark

 

[TheSilverFox]

Because 1) it may reach the listed 'max' length long before the useful case life is used up. i.e. if one is getting 20-25 firings out of a case, you're not going to never trim again just because you did it once when the cases were still virgin? and 2) some people want to keep the case lengths the same because it makes them feel better or they believe it helps on the target.

That means, every time you shoot, you should repeat the trimming process if cases dont have the same length?

It seems like a stupid question but i'm making shure.

 

[steveyrock]

This would be a good question to post over on BR central.I am one of those who it makes feel good to have every case I am going to try and shoot small groups with all trimmed to the same length.

is not the bullet grip affected by varying neck lengths? Maybe I can learn something here.I just always assumed, so I trim.

 

[memilanuk]

About the only people I know that actually trim every firing are HP shooters that happen to have some sort of motorized trimming set up... a Dillon RapidTrim in a dedicated tool head on a 550/650, or a Gracey or Giraud dedicated trimmer,also does chamfer/deburring at the same time). The setup is such that it takes minimal effort to make sure that the cases are the same. They also tend to F/L size a bit more just to make sure that cases will chamber and cycle smoothly during Rapid Fire strings, etc. This causes the cases to grow a little more than they might otherwise.

Most cases don't grow that much... but some, such a .220 Swift, tend to 'grow' a lot... might need trimmed after 2-3 firings, maybe 4. A lot of cartridges can get by 4-5 firings, and some of the Ackley Improved designs,or other ones w/ similar sharp shoulders) can go even longer.

Part of what causes the 'growth' is the amount that you resize the cases... when you work that brass by squeezing the shoulder and body back into place, that metal has to go somewhere, and unfortunately it doesn't go back where it came from,case body and web), so it tends to show up as a gradual lengthening of the neck. Eventually if you push it too long you can end up w/ case head separation and other stuff like that.

I don't shoot BR, so I may be all wet on this, but I was under the impression that they tend to trim very little after the initial trimming... mainly because their chambers are such a tight fit to the brass that they barely size their cases at all, so there isn't much 'growth' going on.

Monte

 

[Clarence]

Just one other opinion as to case trimming,every time) yes it may be paranoia but to trim every time also includes that those cases will PULL the same every time.
The bullet will see a clone with each firing as neck tension will be the same,that is with all of the other factors)ie. turning necks, light tension.
I say trim every time but not too short as you WILL increase the erosion at the Leade if trimmed too short.

Clarence

 

[Rust]

Depends on the rifle. I have two that I keep a pretty close eye on the case length becase I run them very close to maximum length for the actual chuamber measurements. We're not talking about a large quantity of brass here either and the Wilson with the micrometer adjustment makes things pretty easy to get an exact cut. I really like the Wilson with the micrometer adjustment.

besides, uniformity can't hurt.