Working on a new load/chamber 6xc. I understand that new brass is short for the chamber. What's the verdict on working up loads for this new brass, run it full house first time? Or run something light to start and then move on up. Some new Norma brass is measuring 1.487" and fired is 1.496" This is base to shoulder. I have never had new brass that was quite this short or have never took the time to measure it. Wondering if any life or ill affects is in order. Thanks, Matt
Undersize new brass load normal or light first shot.
- Thread starter chuckbuster243
- Start date
D-4297
Gold $$ Contributor
This is a topic you will get varying opinions on . In discussing this issue recently with some our local top Open shooters , I got a consensus that most do their normal full load on first firings , unless the cases were extremely short . And the "extremely short" was also a varying opinion regarding length . Since I don't use Norma brass , I can't offer a valid opinion on it , but Lapua has never been a issue . Even when the cases were .010 short for a .308 case . If this is a major concern for you , maybe dropping your load by half a grain the first time thru, and full load on the second firing would resolve the issue .
I think you can limit forward brass flow by feeding a jam load from the magazine. This should keep the brass against the bolt face during firing.
What about the ejector pushing on the head and firing pin strike forcing the carttidge forward? Im not sure there is a reliable way to be certain the case head will stay against the bolt face that millisecond after the firing pin strikes the primer .
If the bullet is jammed sufficiently long and neck tension is sufficient so there is some back pressure once the bullet unseats itself should hold the brass against the bolt face.
Until the bullet unseats itself it is jammed in the lands and is holding the brass against the face. Once there is enough pressure built up to unseat the bullet that pressure will press the brass back against the bolt face. When once force goes the other comes. Not sure if its enough to keep the brass against the face all the time but its the best I can come up with.
At a minimum you will at least get a good primer strike doing this.
When blowing out improved cases it is recommended to use a good full load and seat the bullet into the lands ,015 to .020 and everytime I've blown out brass the cases have all turned out shorter than the normal case.
It was my impression the OP wanted to load his already dialed in previously worked up load in the new brass and was asking is it worth it ? Or will he just be wasting components because it’s not sized optimally to his chamber ? That’s how I took his questioning so that’s why I answered the way I did .
Sure if you were going to use more neck tension and significantly jam the bullet into the lands which neither is your standard way of loading then then yeah that would work but I’m not really seeing the point of even doing that . That would seem to be just wasting components again and maybe just some cream of wheat and/or whatever other method that works for just blowing out the shoulders would be best .
Sure if you were going to use more neck tension and significantly jam the bullet into the lands which neither is your standard way of loading then then yeah that would work but I’m not really seeing the point of even doing that . That would seem to be just wasting components again and maybe just some cream of wheat and/or whatever other method that works for just blowing out the shoulders would be best .
In these days of reduced component availability perhaps hydro forming is a better option.
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When brass is just a hair too short it can’t form to your chamber. It stretches every time it’s fired. Premature case separation is a risk.
This is when creating a false shoulder is the way to go. Neck up, neck down, and set the head space dead nuts. Brass will last forever and never separates, as it never really stretched in the first place.
Paul
Your assumption is correct. I don't mind reducing the charge and jamming as if I was forming an improved case. My fired brass load is shooting lights out. 39.5 h4350 110smk jumping .010". I am just down with the Rona and was just working some new brass. Had too much time on my hands and pulled a measurement. I won't be able to shoot for a little while so I figured I would see what the consensus is.
Paul, how much should I go up if I try this route? Bring it up to 6.5 and size it back with 3thou clearance or a crush fit? Thanks, Matt
Was the primer backed out at all on your fired brass? If it was you should probably do the procedure I described or do a false head space like Bolt fluter suggested.
If it is fully seated still that means the brass stretch was short enough to reach the bolt face for support. As long as you size your brass longer to fit properly on subsequent firings, case head separation is likely avoidable with normal firing.
Check the case wall head junction with a paperclip to see if there is noticeable thinning from your first shot. You may not need to do anything different if your getting acceptable accuracy and good primer strikes on your first shot. Just size it long after the first shot and you're golden.
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Matt,
6.5 would be about perfect. Try to set headspace with just a little drag on the bolt handle as you close the bolt. Shoot for .001 clearance if you can. Good luck and happy shooting!
Paul
Yes the handful I shot had flattened out and filled the pocket. Accuracy was so so about and inch @ 200 round group though.
Try jamming a few deep with a reduced load and see if that makes a difference. If it doesn't help do what bolt fluter said. Then just size them long for your fireformed loads.
Good luck.
Thanks everyone, I ordered a 6.5 expander (since mine has vanished) I plan on doing a few jammed and a few necked up and set headspace. I will see which one ends up best on target and finish the remaining lot of brass. Thanks again and good shooting! Matt
If you can please follow up with your results here. Any you may want to add some tags to this thread so people can find it with the search function if they have a similar problem.
Fireforming, well, it is NOT the same with every case. General rules, usually apply.....but....
IMHO, back off 0.5 to 1.0 grain, COAL with a 0.010" jam in chamber, and go.
Fireforming, who knows WHEN the brass is actually expanded to actual chamber size in the ignition process. 0.010" is quite a bit of forming.
IMHO, back off 0.5 to 1.0 grain, COAL with a 0.010" jam in chamber, and go.
Fireforming, who knows WHEN the brass is actually expanded to actual chamber size in the ignition process. 0.010" is quite a bit of forming.
This tool works good for forming a false shoulder on a 6BR to be formed into 6 Dasher, it bumps the 243 neck up to ~260, then run it into your already set up size die. I load these to a standard target load that is used for competition.
Brass comes out perfectly formed, get max life out of brass, a tailored load is accurate so no waste in practice.
Jamming the bullet into the lands an a big interference fit neck to bullet works , but is not as reliable as the false shoulder method.
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