Question about trimming new brass

[marksmatter]

I'm brand new to reloading, so please bear with me. After resizing (mainly to round out the necks), my new Winchester 7-08 brass measures anywhere from 2.025" to 2.033" in length. Most cases fall into the 2.027" to 2.030" range. My rifle's chamber can handle case length up to 2.062".

Should I trim the brass down to say 2.027" and make most of the brass the same (keeping the few under that for fouling rounds, etc.). Or, should I not bother trimming at all and deal with this after the cases are once-fired and a little longer in length? Roughly, how much might the length increase after the first firing? Thanks.

 

[wilecoyote]

Re: Question about trimming new brass

a full or neck resizing (to round out etc..)?

 

[marksmatter]

Re: Question about trimming new brass

Full length sizing. That's the only sizing die I have. Some of the necks were dinged up from transit.

 

[iShoot17]

Re: Question about trimming new brass

In my opinion...just load it up and shoot. We are tactical shooters and those .00Xs don't matter as much as they would for a bench shooter. If you want to trim, go ahead, but I don't think you will see any extremely different results (if any at all). You will need to trim once the cases start stretching to over max case length.

 

[bobbyfairbanks]

Re: Question about trimming new brass

If you are going to bother with reloading you should trim your brass. The more variables you can eliminate the more accurate your loads will be

 

[wilecoyote]

Re: Question about trimming new brass

I full resize before the first shot, trimming on a wilson "fixed" bench trimmer,regulated only a little bit less than my chamber can eat_This way,only the really oversize brass will be chopped,and the rest can be fired,even if not exactly uniform_Don't forget that the brass will expand in any direction,not only in lenght,therefore the first time I don't care too much about his "from new"uniformity,because his future growth will depend from the unseeable uniformity of the brass along the entire body_ After the first firing I will consider a more accurate and uniform trimming work, measuring first the headspace obtained after the first shoot,full resizing,or even better,body only resizing, without goin'under this value,and trimming after that_ (I live happy this way,even if better shooters than me for sure will answer in a different direction)

 

[BuzzBoss915]

Re: Question about trimming new brass

I don't see any urgent need to trim your brass, depending on the type of die in use because some have a crimping feature that could cause a problem, if your necks should get too long. But, for the sake of uniformity, you can make them all the same length, if it pleases you. I don't see it as an accuracy issue, case neck length being much less important than neck tension and thickness uniformity.

As far as asking how much your cases will grow in length, that depends on two things. How hot are your loads, and case design.

A gentle sloping shoulder, like on a 220Swift will cause a lot of brass flow and the necks have to be watched carefully after every firing.

On the other hand, I have several rifles chambered for cartridges that have a 40 degree shoulder and in one, I am still using the original 200 cases ten years later and have NEVER trimmed the necks, in spite of very high pressures, so go figure?

In your case, I don't think you will be dealing with a lot of trimming although you provided no loading data. Short answer, don't worry about it. You might go several cycles before you notice anything. But, as a general rule, I would keep them under the max length specs, whatever that is?
BB

 

[wnroscoe]

Re: Question about trimming new brass

Brass should be trimmed to a length of -.010" from the chamber case mouth section. In most 7/08 chambers the length from case head to case mouth is 2.035" - .010" = your trim to length of 2.025"

The thing that you dont want to happen is to bottom out your case mouth in the case mouth portion of your chamber. Set your trim to length up at 2.025" and trim away. If they need it, they will get it.

 

[marksmatter]

Re: Question about trimming new brass

Thanks everyone. I am going to trim, mainly because it'll make me feel better and I want to try all this new stuff out. By the sounds of the responses, I may not gain anything, but I won't hurt anything either.

Sorry for not providing any load data, but I never thought about that, and it is in-work. I'll be starting at Hodgdon 4350 book min for 7mm-08 162 gr. and working from there.

Cheers.

 

[targaflorio]

Re: Question about trimming new brass

I debated that with myself. But since the Wilson trimmer needs a separate case holder for new brass, I decided to shoot them as is. All my win brass has measured under the book max for 308 and 300.

 

[Deadshot2]

Re: Question about trimming new brass

A good number of the BR shooters will tell you to not bother with the brass until you've shot it once. At the most, they'll run an expander through the neck using something like a Sinclair Expander die. All it does is make the ID of the case neck the same size leaving a couple thou for neck tension. Also removes any out of round or bent edges.

After the first firing, the case can be trimmed and it will then remain pretty uniform over the next few firings.

Until your new brass has been fired one time in your rifle it won't be as uniform in other parameters either. Load performance for a new case can vary greatly from that of a fired case due to volume change if nothing else.

 

[Greg Langelius *]

Re: Question about trimming new brass

Load and shoot, measure after subsequent resizing. When it reaches max length, trim it to trim-to length.

There's really nothing more to it unless you want to make it more.

 

[Deadshot2]

Re: Question about trimming new brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">
There's really nothing more to it unless you want to make it more. </div></div>Now where's the fun in that?