Originally Posted by shawn338lapua
Ah sorry Boomtube, when i am running brass they come in contact. And as far as the section in my book about Op, well lets just say i am learning. or trying to anyways....
"The easiest way to ascertain if, the die is setting back the shoulder and how much is using a headspace gage. The die will only set back whatever distance is obtainable when the die is in a 'cam over' position in the press, but once you grind the die base or shell holder, camming over becomes a thing of the past.
I never cam over my press to bump."
Which Headspace gage would you recommend? i do have the LE wilson non adjustable
I am ok with the idea of grinding my die, no plans on selling it. though i do not have access to a decent shop. suggestions?
I use the Hornady headspace gage that comes with an assortment of pre bored inserts for most popular calibers (and you can get from Hornady a blank insert you can custom bore for a wildcat if necessary. It clamps to the moveable jaw on your calipers. I clamp mine to my Starrett's.
I take a fired round (from whichever rifle you want to set the headspace on) and use that as the standard. It won't matter if that round has base issues like brass on the bolt face because when you fire it, the case is assuming the neck and shoulder imprint of the chamber and you are only using the shoulder (datum) to ascertain the amount of bump.
You just can't 'mix and match' because every rifle in any certain caliber, will headspace a bit differently. I segregate the case I use as the standard for a particular firearm by marking it.
My typical bump is 0.001-0.002.
I just happen to have the machinery (high precision surface grinder) to grind shell holders and/or die bases dimensionally square.
It would be impracrtical to attempt to 'mill' a shellholder or a die base because of the issues in fixturing them rigidly enough to actually employ a cutter in metal removal and most shell holders are case hardened anyway so the best way is grinding.
If you grind the die base it's not resaleable of course.
My issue with camming over the press (interference contact between the die base and shell holder) is, you really don't know how much the shoulder is being bumped back (without a headspace gage) and I don't care to cam over the press because it imparts a strain on the mechanism.
Because I load straightwall cases with carbide inserted dies for pistol rounds, 'camming over' is a no-no. You cam over a pistol die and it's shot because the carbide insert is brittle and will shatter.
You can buy dedicated bump dies that are basically a sizing die with an abbreviated base. I can't see spending the money for yet another die when the alternative is simpler.
I never really got into this 'bump' stuff until I started loading for longer range bolt guns. AR's and such care less about headspace. So long as it cycles in basically a sloppy enviroment, all is good. One reason I've never considered any gas blowback semi auto a viable long range hunting tool.
You can hand grind the base (of the die) after removing the decap rod and expander ball on a bench grinder with a medium (not coarse) wheel by engaging the wheel lightly with the die base and rotating it to achieve an even cut. You have to be damn careful about how much you remove and that you keep the base even and square to the die body.
I would use your calipers to ascertain the overall length of the die prior to grinding (for a base line about how much to remove) and then CAREFULLY GRIND the base as I suggest above. Grind a little, I mean a LITTLE and then check the overall length in 3 different spots around the diameter of the base (to insure that you are grinding evenly and keeping the base square).
Takes me about a minute with the surface grinder but can be accomplished by hand being careful.....