New brass length?
- Thread starter muleman69
- Start date
Dont go by book length. Forget you even saw that... measure YOUR chamber length.
Books are wrong in that since. Its not a trim to length to use. You gotta figure out your chamber and trim, size, and seat bullets to your chamber...
Whst I do? right or wrong... I measure all the new brass, find the shortest, then trim to that length... Thst way they are all the same. reload shoot em, and keep it consistant for me chamber from there on out..
Books are wrong in that since. Its not a trim to length to use. You gotta figure out your chamber and trim, size, and seat bullets to your chamber...
Whst I do? right or wrong... I measure all the new brass, find the shortest, then trim to that length... Thst way they are all the same. reload shoot em, and keep it consistant for me chamber from there on out..
I've run into this problem. It's exacerbated by the inability to find a guaranteed precise object that you can test your calipers against that is near the length of the brass. Your calipers can be off on the low side and you can send the brass back to the manufacturer and they can tell you that it is the correct length and you can't verify their claim. They can provide short-necked brass, not just below the trimto length but also below SAAMI minimum specs and get away with it. This can leave you short of an accuracy node in bullet seating depth because you have to have a minimum amount of bearing surface of the bullet in the neck. Without a way to prove the accuracy of your calipers, you're hosed.
Presumably, the rifle manufacturers have built their chambers roomier than minimum SAAMI chamber specs so that factory ammo, which should be constructed at or below maximum SAAMI cartridge specs, will not overpressure. If your brass is well below SAAMI minimum cartridge spec even fireforming will not grow the length up to the trimto length. So you won't be able to get brass that fits your chamber well.
But here's a concern. If your calipers are telling you that the brass is near SAAMI maximum cartridge length and your calipers are reading lower than the brass actually is, your brass may be exceeding the SAAMI maximum cartridge length by enough to get the neck pinched down by the end of the chamber, which can produce overpressures. This is why they sell go and nogo chamber guages.
Presumably, the rifle manufacturers have built their chambers roomier than minimum SAAMI chamber specs so that factory ammo, which should be constructed at or below maximum SAAMI cartridge specs, will not overpressure. If your brass is well below SAAMI minimum cartridge spec even fireforming will not grow the length up to the trimto length. So you won't be able to get brass that fits your chamber well.
But here's a concern. If your calipers are telling you that the brass is near SAAMI maximum cartridge length and your calipers are reading lower than the brass actually is, your brass may be exceeding the SAAMI maximum cartridge length by enough to get the neck pinched down by the end of the chamber, which can produce overpressures. This is why they sell go and nogo chamber guages.
SAAMI is a standard by agreement of the signatories, not a statutory one.
What is the point of agreeing if you're just going to ignore what you agreed to?
If it was the law, the ambulance chasers would be sniffing round.
For an ammo manufacture in court, keeping your cartridge length within SAAMI specs would protect you. For a rifle manufacturer in court, keeping your chamber length above SAAMI minimum would protect you. You don't need laws for that. The issue here is when your brass length gets too low. Now we're talking about consumer protection against fraud. By openly being a SAAMI member, they are advertizing that they comply with SAAMI standards. If they sell something off-spec and nobody got hurt or died, suing them is too costly. They know that all they have to do is lie about the length or replace the product endlessly until you get tired of paying for shipping. So as I said, you're hosed.
But again, if you have no way of proving the accuracy of your calipers, you're just as stuffed.
There is NO danger in using brass that is too short in whatever length you think is minimum. It poses no concern as it can’t affect function in ANY way.
When I fireform ANY of my improved chambers, the brass ALWAYS SHORTENS by .020”-.030”. No reloading technique changes this fact. It is perfectly safe to fire after this and will grow in time to the necessary length.
Now, if you have brass that is .040” LONGER than SAAMI max, you MAY have an issue of the case mouth being pinched in the chamber end causing excessive pressure.
I make a gauge so that I KNOW what length my brass can grow to and trim when it gets within .010” of that number, for instance, my 300WM has a chamber that measures 2.638” to the end of the neck. I can, and do, let the brass grow to 2.635” then trim to 2.630”, this is .030” longer than SAAMI MINIMUM.
Short brass poses NO PROBLEM TO FUNCTION OR SAFETY. It WILL grow as you fire it.
Cheers.
Oh my
KMart
Gold $$ Contributor
Don't worry about .010" short. A dollar bill is about .005. After you fire it one time and properly resize the cases in your chamber, you may have to trim it to get it to the length you want.
A little clarification on a few things here. Yes, SAAMI is a voluntary organization, and they don't carry force of law behind them. It's simply an agreed upon standard that ensures that if everyone adheres to that standard, everything should be functionally interchangeable. Most follow those guidelines as it sidesteps a lot of potential problems we'd all rather avoid. CIP is another matter entirely. They do carry force of law with member companies, and can shut down an operation if that company is making something that falls outside of their established guidelines. They also have a very specific set of regulations regarding cartridge identification and nomenclature, which is why there is both a 6mm Remington BR and a 6mm Norma BR. While the cases are interchangeable, the differences in the throating between them makes them two totally different cartridges in the eyes of CIP, requiring a different name to separate the two.
As for length, both CIP and SAAMI will list a Maximum case length, which is where the chamber may be expected to end on a standard chambering. Cases extending beyond this length have the potential to become "crimped" by the end of the chamber which becomes a serious safety issue. The minimum case length is normally Maximum -.020". The "Trim to" length listed in most manuals is actually something of an arbitrary number, .010" under Max, and roughly halfway to the true Minimum.
As for length, both CIP and SAAMI will list a Maximum case length, which is where the chamber may be expected to end on a standard chambering. Cases extending beyond this length have the potential to become "crimped" by the end of the chamber which becomes a serious safety issue. The minimum case length is normally Maximum -.020". The "Trim to" length listed in most manuals is actually something of an arbitrary number, .010" under Max, and roughly halfway to the true Minimum.
NorCalMikie
Gold $$ Contributor
Write that figure down and refer to it what you check case length. You may go a long time before any trimming is needed. And die styles make a big difference on case lengths. Full length dies neck buttons will pull the neck longer on every stroke. Shoulder bump dies don't work that way. Short brass, not too bad. It's the long ones that need help.
I have BR brass with 20 to 25 resizes on them and still no trimming needed. You figure out what works best over time.
muleman69
USMC -1st marine Div. RVN
Calipers are good as I have five pair and good mic's to check them with
muleman69
USMC -1st marine Div. RVN
. calipers are good, I will go with the short cases . TKS
muleman69
USMC -1st marine Div. RVN
7MM/08 and 300WM ,both with the Nosler brass.
Lone Hunter
Silver $$ Contributor
I think all the brass I've ever got from factory to component brass in the 6.5 Grendel has been short. I will let it grow then trim it. Never had a problem with short brass. Too long brass is a different matter. My other calibers I check my chamber with the Sinclair Chamber Length Gauge. Simple little tool that works.
https://www.sinclairintl.com/reload...s/sinclair-chamber-length-gage-prod32925.aspx
https://www.sinclairintl.com/reload...s/sinclair-chamber-length-gage-prod32925.aspx
If you don't consider having the ability to seat bullets out near the lands, you are correct. It is off-spec and may limit achievable accuracy, but not dangerous.
Are you trying to reach the lands on a factory chambered barrel?
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