Giraud. If my brass doesn't need trimmed, what do you do?

[dave300]

So here is my question;
I have a few 300 Rums, stock Senderos, Im doing the load workup for.
SAAMI is 2.850 OA case length, and very seldom, if at all, do any of the brass grow to the 2.850 length, some are close such as 2.848, but usually less, ranging from 2.843 to around 2.847 for most of them.
Having said that, I have read that a carbon ring can build up if the brass is cut to short, (shorter than the actual chamber), I understand that, but don't have the experience to agree or disagree?
(I have chamber plugs on the way to measure the actual chamber), but I anticipate the chamber will be greater than the fired brass, and as I said, after 5 firings the brass is still not up to SAAMI max length.
I prefer/wanna use the Giraud to chamfer the brass mouths for consistency, and if I were to just "touch" the case mouths Id have to be adjusting depth all over the place due to the inconsistent OAL. I don't want to cut them back needlessly to obtain the chamfer, or, should I measure the shortest piece and trim the rest to that shortest ones length?
Or just leave them alone with the Giraud and hand chamfer at whatever length they are, until, if ever they exceed chamber depth?
What if any accuracy is lost when brass varies by as much as .006 OAL?

 

[ZombieMonkey]

Even when my brass needs very little trimming I still run all of my cases through the Giraud. It cleans the necks up very well and also ensures that every piece has a consistent length rather than having to check brass. It's so quick I can't see any reason to not do it as it does a better job chamfering the necks both quicker and more consistently than I can do with the RCBS powered case prep center. I usually keep my brass just a little over the recommended trim lengths though, I don't ever let it get to the SAAMI max.

That's how I do it, your mileage might vary.

 

[LawnMM]

I assume you have once sized brass, reloaded and it does not seem to grow to the length you are expecting.

If that is the case, it is almost certain you are working your shoulder bump more than .001-.002. If you are bumping the brass back more than that, be sure to look for early sings of base separation. You need to feel the inside of the case for ridges. Over bumping is incredibly common if you set up your dies as most mfgs suggest.

So before you worry about inconsistent neck length. (Not great for precision shooting), make darn sure your not over sizing.. Bet a donut you are..

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What he said. Ideally you should drop the brass into the giraud and have it just barely trim the tip. If it isn't growing to that size you are probably over sizing. You should be bumping the shoulder about 0.002 for a bolt gun from fired brass.

 

[FLIGHT762]

Don't be surprised when you measure the chamber length with a gauge you get a reading of .025"or so over SAAMI maximum length. When I measured a few of my 308 rifles' chamber lengths, I found lengths actually .025"-.030" over the SAAMI maximum of 2.015". I was getting chamber lengths of 2.040"- 2.045".

Like a couple of others have suggested, you should be more concerned you are not over sizing (bumping the shoulders back) too much on your brass. If you're not measuring the shoulders of your fired casings, you should be. There are a number of bump gauges out there. My preferred gauges are the Hornady and the Sinclair gauges. They will help you set your F/L die not to bump too much.

You might get lucky with your Rifles and find the fired cases are within .002" or so of one another. If they're not, you need to segregate the brass for each rifle and bump accordingly. A set of Redding's competition shell holders can help you do this without having to keep adjusting your F/L die for each rifle. I do this with the 4 308 Winchester rifles I reload for.

 

[dauntedfuture]

Its easier for me to trim them in my Giraud then it is to measure them...

 

[dave300]

Thanks guys,
I do in fact bump my shoulders back .002 from 2.868 to 2.866. I have always done this and do use the stepped shell holders, measuring with the hornady headspace D400.
So what I am understanding, is that it is acceptable to trim the brass back to the same length of the shortest full length sized case?
I feel like might be missing the point here, or should I just trim to the shortest piece as I stated above?
Thanks and sorry for the request for clarification.

 

[jmorris]

If the case does not need to be trimmed the cutter won't cut it. No magic here.

 

[dave300]

If the case does not need to be trimmed the cutter won't cut it. No magic here.

Thanks, but I want to chamfer and bevel the inside and out of the case mouth, after FL sizing, so if the brass doesnt need trimmed, it doesnt get trimmed, but it also doesnt get chamfered. That is understood, I am asking how to get it chamfered and not "overtrim" and what are the ramifications of being a bit undersized on case OAL?

 

[FLIGHT762]

Wait until you get your chamber length gauge to see what the actual maximum case length is and go from there as to where your Giraud setting will be. If your cases need a chamfering, buy one of the VLD chamfer tools and do it once until the case needs trimming.

You're over thinking this.

 

[jmorris]

That is understood, I am asking how to get it chamfered and not "overtrim" and what are the ramifications of being a bit undersized on case OAL?

If the case is "under" it may or may not hit the inside/outside, just depends on how much under.

You can only trim more off the length if you lower the cutter enough that the center of the rim is cut. Think of the inside and outside chamfer as the sides of a "V" the length is changed by the bottom of it. So if you had shorter cases the actual cut would be smaller than full length "v" vs "V" the angles are the same just less material removed.

 

[dave300]

What I figured, so using the Giraud is kinda of not gonna happen the same for all the brass.

If the case is "under" it may or may not hit the inside/outside, just depends on how much under.

You can only trim more off the length if you lower the cutter enough that the center of the rim is cut. Think of the inside and outside chamfer as the sides of a "V" the length is changed by the bottom of it. So if you had shorter cases the actual cut would be smaller than full length "v" vs "V" the angles are the same just less material removed.