This is what I measured on before and after using a standard Forster BenchRest F/L die. I used a Mitutoyo digital caliper. How could your case expand .0175" at the base?
reloading issue
- Thread starter chuckdds
- Start date
That is what i was trying to imply..
okie
Gold $$ Contributor
how much do small base dies resize??
Here ya go.. feast on it!
http://bulletin.accurateshooter.com...th-dies-neck-sizing-dies-and-small-base-dies/
okie
Gold $$ Contributor
thanks
You have a factory barrel and the lawyers are not going to let factory chambers go out with short throats or tight chambers. You're not going to touch the lands with a cartridge that fits the mag. Your chamber dimension seems in line with SAMMI dimensions too. I'd switch the case lube and your problems should go away. As good as IMI brass is, they still have to make it smaller all the way around so it fits all chambers. Once you fireform you should be good to go. If you're into the lands on those single shot fired rounds you may have developed higher pressure than you think. This whole thing about sticky bolt lift, and flattened primers is not a good way to determine high pressure. In my 50 plus years of reloading, head diameter expansion is the best way to judge pressure. Drop your fireform load 10% and see if you still have the same expansion using the same COAL.
Without question, Imperial sizing wax can only improve a difficult situation. I was having problems with my 6mmAI to the point the brass broke off at the neck and I ended up sending it to RCBS to remove. When they sent back the die they included a small can of it. I've never had the problem again.
I faced the same issues in my Remington xcr and went shorter. I got 5 shots into a dime at 100 yards only problem was it wouldn’t fit the magazine. So I went shorter and eventually got 5 shots into 3/8s at a 100 yards. Good luck
i believe i would snatch that barrel off and turn that rifle into a remage.
http://northlandshooterssupply.com/match-grade-barrels/criterion-remington-remage/
truth is you probably don't even need to bump that shoulder yet. just set the die up to neck size until the brass is fully fireformed and the shoulder headspace dimension stabilizes.
http://www.saami.org/PubResources/_CC_Drawings/Rifle/308 Winchester.pdf
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Thinkin’ when you full length sized the possibly already a bit short, from case head to shoulder datum, virgin brass that the case body due to the FL (body) die’s adjustment moved the shoulder datum even closer to the case head. One firing of the virgin brass then left the shoulder datum .009” further forward, that’s a lot. If the once fired case chambers easily without it being resized, that’s telling its now .009” longer case head to shoulder datum dimension is still shorter than the distance from the bolt’s face to the chamber’s shoulder datum, so there’s no need for the FL (body) die’s shoulder to even touch the case shoulder whilst it’s resizing only the case body and neck diameters.
&&
Thinkin’ when you full length sized the possibly already a bit short, from case head to shoulder datum, virgin brass that the case body due to the FL (body) die’s adjustment moved the shoulder datum even closer to the case head. One firing of the virgin brass then left the shoulder datum .009” further forward, that’s a lot. If the once fired case chambers easily without it being resized, that’s telling its now .009” longer case head to shoulder datum dimension is still shorter than the distance from the bolt’s face to the chamber’s shoulder datum, so there’s no need for the FL (body) die’s shoulder to even touch the case shoulder whilst it’s resizing only the case body and neck diameters.
looks like your brass is slowly conforming to your chamber.
you don't need to bump that shoulder until that base to shoulder datum number stabilizes. probably 3 firings. until then just set the die up to neck size. even then you should only try for a .001 difference between fired and sized.
you certainly don't need small base dies. Give that brass a few more firings and see if the rest of your numbers don't get better. if they don't then your two choices are custom dies to match your chamber or a new barrel.
oh and imperial sizing wax is the way to go and their dry neck lube for neck sizing with an expander ball
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