I recently purchased a browning a bolt in 270 winchester. After 3 firings on brand new winchester brass i noticed the famous ring around the web but only on one side. I cut one in half and sure enough there seperating but only on one half, i looked at other cases and they have a sharp bulge on half of the case almost like one side of the chamber is outta round. Im fl sizing and am only moving the shoulder .001" so they chamber. All cases are doing this with light loads or max loads. No diffrence in them. Im usally shooting 59gr of h4831 with a 130gr accubond. Im stumped and it sucks only getting 3 reloads before trashing the case.
Incepient case head seperation after 3 loads.
- Thread starter Mtstalker
- Start date
How are you measuring your fired brass and do you have any new (same brand) to compare them to? dedogs
What's your reloading procedure ? What kind of dies , press etc .
If the dies are KNOWN TO BE GOOD , as used and never had this problem , have the headspace checked . The dif between go and no go is USUALLY.003 , add to that the tolerance stacking of min brass , shell holder and dies , it could be a combination of them
If the dies are KNOWN TO BE GOOD , as used and never had this problem , have the headspace checked . The dif between go and no go is USUALLY.003 , add to that the tolerance stacking of min brass , shell holder and dies , it could be a combination of them
Rcbs dies,shellholder and press. Fl sized with .001 shoulder bump. Imperial sizing wax is used. I checked and the die is sizing body to sammi spec. Between fired and resized the body below the shoulder is .002" smaller after resized same with right above the web. The ridge does get slightly smaller after resizing. But it does become more prenounced after firing. Cases are trimmed to spec. No signs of pressure and the weird thing is that this rifle is rhe most accurate one i own.
BoydAllen
Gold $$ Contributor
Avoid light loads for your first firing on a case. load safe but stout, make sure that you decap before measuring fired cases, measure several, and then use the largest of these measurements to set your FL die so that sized cases measure the SAME as your reference fired case, then check to see how the sized cases chamber. With the shallow shoulder angle that your cases have, the combined force of the firing pin strike and the force of the primer explosion against the bottom of the primer pocket will force the the case forward from where it would stop if simply pushed forward in the chamber manually. As the pressure in the case rises the body of the case expands and friction locks the case in this forward position. At some point the pressure becomes high enough to stretch the case near the head, where you are seeing the bright line, to the point where the head is stopped by the bolt face. Light loads can actually shorten the head to shoulder dimension. We bump to created clearance, but if there is already longitudinal clearance then all that may be needed is to reduce the diameter of the body. Cases take more than one firing to reach their maximum shoulder to head dimension. Just to get a better idea of what is taking place, before you decap, hold the case between the jaws of a caliper so that one jaw is across the mouth of the case, and the other across the head centered on the primer, then hold the case and calipers up to a bright light source so that you can see if there is a gap between the jaw and the case head on both sides of the fired primer. Light to average loads will show this gap, and the amount of primer protrusion will correspond to the clearance that the case has longitudinally.
Please describe how you set up your die. dedogs
I fired them all at first with 59gr of h4831.60gr is max for this rifle. I did decap before measuring and i backed out my die to increase length when sized and then ran it down in .002" increments untill they would chamber with little resistance with the firing pin removed. This measurment was .001" less than the fired cases.
Trash that brass and get some Norma .270
As far as it being on one side , if it's not an off centr large chamber its gravity with the case just resting on the bottom of the chamber . I would measure the bulge , if over chamber specs , you have an oversize chamber . If at or under chamber specs it's your brass or reloading equipment /procedure.
New dies , I suspect those are the problem if the brass bulge measures at or less than the chamber specs
New dies , I suspect those are the problem if the brass bulge measures at or less than the chamber specs
Have you tried Boyd's method (above) of measuring a fired case before de-capping? dedogs
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