Brass Trimming question - .243 Win.

[Rmitch223]

Brass trimming question: After this initial load testing I noticed that the cases have stretched slightly (not unexpectedly of course). They are different lengths, I assume because of the different charge weights. None of them are over the max length of 2.045". Should I trim them all to a equal length or not worry about trimming this time around because they are not passed the max length? Would I gain consistency by trimming them all to the trim to length of 2.035"?

Initial testing was done with brand new never fired Remington brass.

 

[PJGunner]

I usually trim after resizing the brass after each use. Depends on the cartridge. Some hardly stretch as all and some like my 7x57 brass stretch with every firing. So, to keep it simple I just trim afer each use. I have one case trimmed to proper length and use it as a master to set up my RCBS trimmer.
paul B.

 

[CatskillCrawler]

If my brass differs by more than .005" I usually make them uniform. I always trim new Rem, WIn and Hornady brass after I re-size it before loading them for the first time. Length uniformity of new brass is usually spotty at best.

 

[nosler06]

I usually trim after resizing the brass after each use. Depends on the cartridge. Some hardly stretch as all and some like my 7x57 brass stretch with every firing. So, to keep it simple I just trim afer each use. I have one case trimmed to proper length and use it as a master to set up my RCBS trimmer.
paul B.

Paul that is about the best little piece of advise that I have seen. Thanks. I have always set up my RCBS trimmer with the mic and checking the first case and adjust it from there. Keeping one piece of lengthed brass as a template saves alot of fussing around.

 

[theseeker]

In my experience case length is not critical, and doesn't effect accuracy.

 

[300WSM]

If all the brass is new and you are certain is the same brass and shots fired...Don't worry about it until you get some cases close to the OAL maximum. When that happens trim them all to .010 below the listed max OAL. Even the ones not measuring as long as the others. Then you will see them all stay the same length.

 

[AzDak42]

I usually trim after resizing the brass after each use. Depends on the cartridge. Some hardly stretch as all and some like my 7x57 brass stretch with every firing. So, to keep it simple I just trim afer each use. I have one case trimmed to proper length and use it as a master to set up my RCBS trimmer.
paul B.

I've had reasonable luck just sizing and shooting new brass, without trimming it. But after the first firing, I trim. At that point, They tend to stretch uniformly and I end up discarding them before they go over max.

 

[PJGunner]

In my experience case length is not critical, and doesn't effect accuracy.

You're quite right. It's not so much an accuracy thing; more of a safety issue. Once the brass stretches past the max allowable length, it could easily be jammed just enough into the throat that the neck cannot expand enough to release the bullet and a much higher pressure occurs, potentially to the point of damaging the gun and shooter. Not a place I want to be.
Paul B.

 

[Mountain Goat]

I will trim new brass just to square up the mouth. As Paul B. noted, if a case is too long it could lead to a dangerous situation. Brass that is trimmed way too short poses little safety risk but could lead to advanced/unnecessary throat erosion. I keep a trimmed case and a dummy round for each bullet I use inside my die box. That can be a time saver when it comes to setting up the trimmer and seating die.