I got a giraud trimmer last week and was going to set it up today. I have a few hundred once fired lapua brass that have varying headspace measurements currently since it is only once fired. My question is since it trims based on the shoulder should I not use the giraud on the lapua brass till it has been fired 2-3 times?
- Thread starter SleepDoc
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I dont think that it will make all that much difference, just make sure you size them all the same before you trim them.
Once fired in your gun? If so I doubt that shooting them again would grow them long enough to fill the neck so it wouldnt hurt if you wanted to test this yourself, I just know I wouldnt bother worrying about it and would trim them all after sizing.
Once fired in your gun? If so I doubt that shooting them again would grow them long enough to fill the neck so it wouldnt hurt if you wanted to test this yourself, I just know I wouldnt bother worrying about it and would trim them all after sizing.
To the OP. Generally, that is correct. The brass should not need trimming until at least three firings. Unless you have 'semi-processed' new brass. But since you said once-fired.
The once fired brass is probably the 'best' it will ever be for your rifle. If it was fired from your rifle. Because now it's fire-formed to your chamber. You can neck size 2 more times and then you probably will need to trim, full-length resize and re-fire-form. And go back to your brass being great again.
The Giraud is the Rolls-Royce of trimmers. Fantastic. I have one with several heads. and love it. But with once-fired brass, the neck likely won't even reach the cutter.
Cheers,
Sirhr
The once fired brass is probably the 'best' it will ever be for your rifle. If it was fired from your rifle. Because now it's fire-formed to your chamber. You can neck size 2 more times and then you probably will need to trim, full-length resize and re-fire-form. And go back to your brass being great again.
The Giraud is the Rolls-Royce of trimmers. Fantastic. I have one with several heads. and love it. But with once-fired brass, the neck likely won't even reach the cutter.
Cheers,
Sirhr
As mentioned above - If it is fire formed from your gun then set it up using those cases and you will be GTG. If you have .001 variance in your headspace then you will see approx. .001 trim length difference as the trimmer indexes off the shoulder.
Now if the brass was not fired from your gun and may have come from several guns then you will not want to use the trimmer until all of your brass is very similar. The varying headspace for each round will not allow you to get a consistent trim length. I used a different trimmer the first time since I wanted to keep everything uniform and not have varying neck length which could or could not effect neck tension etc.
PS: If you like the current debur/ chamfer angle then do not remove the set screw and try to adjust it! I bought mine used and wanted to make a few adjustments with it and needless to say, its an art to try and get it exactly how you want it. I wasted more than a few cases trying to get it set up correctly.
Now if the brass was not fired from your gun and may have come from several guns then you will not want to use the trimmer until all of your brass is very similar. The varying headspace for each round will not allow you to get a consistent trim length. I used a different trimmer the first time since I wanted to keep everything uniform and not have varying neck length which could or could not effect neck tension etc.
PS: If you like the current debur/ chamfer angle then do not remove the set screw and try to adjust it! I bought mine used and wanted to make a few adjustments with it and needless to say, its an art to try and get it exactly how you want it. I wasted more than a few cases trying to get it set up correctly.
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Since you have several hundred: measure and find five of those which are longest and five which are shortest, size them while maintaining the two groups and then trim. See how they compare to one another and decide if you can live with it
Yes, they were all fired from my rifle. I full length resized them and ran mandrel die through them but noticed up to 3 thou variation in the headspace measurements of the once fired cases. I do have 5 cases that are 3x fired so I could figure out what the final headspace was going to be on my rifle when I was setting up the sizing die. This may be a dumb question but the case that came with the trimmer I measured a headspace of 1.4965 and case length of 1.9055 and I set my sizing die to size 6 thou larger. Does that mean if I run a case through how the giraud is currently set up it will trim it 6 thou longer than the case that came with the trimmer?
No sure way to tell for sure, there could be a slight difference in the shoulder angle and case holder itself that could vary it a bit. I aim for 1.750" as +\-.010 either way is the min and max saami spec
Agreed. When I've measured once fired brass that's not FL resized, it measures shorter than before it was fired, Probably because the shell didn't fully spring back.
Sort of like my gut these days.
Unless you are firing from a gas gun, do yourself a favor and get yourself a set of neck sizing dies. Then after first firing... only neck size. For 2 or three more firings. Then FL resize again. And trim. Once you fire form the case to your chamber, your neck sizing will give you the best possible brass. For your rifle. But after a while, you have to FL resize it again and then re-fire-form. Then you will have brass that is great for your rifle again. May have to anneal.... but that's usually after the 2nd 'round' of neck sizing. Depending on brass. Some of this is art, not science!
If using a gas gun, you need to full-length resize after each firing and may need a small base sizing die. And after about three firings will definitely need trimming. But for a bolt gun, you are focusing on the neck most of the time.
I am not sure about the headspace and length question.... not processing it in this context. I'll think about it.
Cheers,
Sirhr
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Several preferred methods. I partial FL resize for the life of the brass. Trim when a sample shows they are exceeding SAAMI. As an aside, Possom Hollow trimmers are the easiest to set and don't cost an arm and a leg.
I have a Giraud Tri-Way trimmer for my .223. I size and trim all my once fired brass so that they start out all the same. We're talking 5-6 seconds on each piece of brass and you're done.
Hopefully one day I'll have the Giraud bench top trimmer.
Hopefully one day I'll have the Giraud bench top trimmer.
Unless your shooting full on competition benchrest, trimming is a safety step not an accuracy step, trimming to book minimum, i.e. 2.005 for a 308 is a bad practice imho, let the brass grow until its .010 - .015 from the end of the chamber, Sinclair sells a tool to measure your chamber, congrats on the Giraud.
I bought that sinclair tool and measured my chamber to be 1.9390. Book max for 6.5cm is 1.9200 and trim length 1.9100. The instructions with the sinclair tool say trim to minimum of 0.024 from chamber measurement. Is that where I should set the trim length or that is a cover their ass quote you think?
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