Question

[Dirtlaw]

If the brass expands to seal off the gases, it has conformed "perfectly enough". If it didn't, you'd see scorch marks out to the point where it leaked out. If the scorch marks are around the neck and do not extend all the way down the case, it still sealed the gases, just not before the bullet left the case mouth.

Are you seeking to waste time for no good purpose? If so, this is a good endeavor.

Rocketman II. Here is my best answer. All I know is that the numbers keep improving. But you are right, no one cares when we finally are pushing up daisies. The other side of the coin is that it feels good now when I see the numbers improving and when everything becomes tighter. It may be a fools errand I agree. But success feels good no matter if it is just reloading ammunition. When things stop improving I know it is time to move on. Because God has been generous to me I am now able to improve my ability to measure parameters that a few years ago would have been impossible. I honestly believe I still have room for improvement. In today's world I can't say if maximizing your ability is a worthwhile goal. All I can say is that it feels good to me.

[Dirtlaw]

Dirtlaw
Back in the old days it was common to true up the casehead in order to keep primer pocket life longer.

Flat caseheads convex caseheads and concaved caseheads last different amount of firings before the primer pockets would loosen up.
Today we use Lapua brass and that problem has gone away.
You can also buy machined brass from RCC that isn't stamped.

Thank you! I continue to learn. That feels as good as success with improvement.

[Dirtlaw]

I lucked out big time by those odds. Married the perfect woman, had two perfect kids, and now have three perfect grandkids.

Two of my four is the perfect God and the perfect wife.

[the86d]

Laziest title ever: "Question"

Answer: Compose a detail-oriented subject/thread title.

The Internet, and forums aren't corporate e-mails with half-azz management... ... ...

School will never apparently teach this.

Question

Talk about LAZY people wasitng other people's time, AKA: Click-baiting.

[MongooseV8]

Youd probably find more spent brass stuck in your chamber after the extractor rips off the rim. It also wont improve your ammo since the whole case is full of variances that you cannot control. IE wall thickness and head thickness.

[Dirtlaw]

Youd probably find more spent brass stuck in your chamber after the extractor rips off the rim. It also wont improve your ammo since the whole case is full of variances that you cannot control. IE wall thickness and head thickness.

YES. Controlling the variables is a difficult (if not impossible) task.

[rplaw]

YES. Controlling the variables is a difficult (if not impossible) task.

Machine your own brass from bar stock on the tightest tolerance equipment you can get with the best tooling possible. Invest in precision measuring tools that go beyond the std 3 decimal count for use when reloading. Measure and weigh everything and group like to like components together.

In the racing world, it's called blueprinting. You can't control variation, but you can minimize the deviation between components.

[divingin]

The base of the case is the reference point for some important measurements. It is stamped but not machined. What issues would arise if you very slightly machined the base so that it was perfectly flat and perpendicular to the walls of the case?

Do you know it's off? Just because it's stamped doesn't mean it isn't concentric.

That said, I doubt you'd run into problems if you just trued up the base of a case (skim-cut the high side), but I am also fairly certain that you wouldn't gain anything, either. The body of the case is located by the chamber walls, so any deviation in the case head won't mean much, and will become formed to your chamber/bolt on first firing anyway. And if there's something off in your chamber/bolt combo, you'd be machining the cases between every firing.

[Dirtlaw]

Machine your own brass from bar stock on the tightest tolerance equipment you can get with the best tooling possible. Invest in precision measuring tools that go beyond the std 3 decimal count for use when reloading. Measure and weigh everything and group like to like components together.

In the racing world, it's called blueprinting. You can't control variation, but you can minimize the deviation between components.

I agree with the philosophy of what you are saying. And, a lot of the points you mention are or could be goals -- though I doubt whether I have enough life left in me to form and machine my own brass ... a bridge too far I'm afraid. But I am somewhat of a zealot in taking measurements. That is what caused my post. I can approach 1/100 of a grain and 1/10,000 of an inch which is of course more than I need.


What led to the post is the variance I get when I make repeated measurements of the headspace length of a particular round. I believe it is because the base is not truly perpendicular to the case walls ... meaning that there is a short side and a long side when measuring the headspace "distance" it needs. Bottom line, there is more variation in the measurement than I want.



In using the Hornady tools the problem that I've encountered is that the round can be canted in the calipers which leads to error. To avoid that I made a jig that holds everything perfectly square and I use high precision dial indicators on a surface plate. Perhaps I never will find the answer. But I still get pleasure out of continuing to look for it.

[MongooseV8]

One thing you can do is weigh and sort new brass to help minimize head and wall thickness.

[stilly]

The base of the case is the reference point for some important measurements. It is stamped but not machined. What issues would arise if you very slightly machined the base so that it was perfectly flat and perpendicular to the walls of the case?

That sounds like something that Stilly would do. Cept he would not care to waste his time on it.

You know what would be better though, why stop with just that? I say it would be even better to put that case in a 3 or 5 axis mill and grind slight dimples in the case (after you resize it of course) so that it looks like a golf ball. Then load it with some cool patterned PC pill and use it for photos...

[divingin]

As an aside, I have taken a case and rotated the base against some oiled wet/dry abrasive paper to remove ejector marks on brass where I got a little aggressive with charges.

I've also seen semi-commercial brass that I suspect was Mexican-Matched where they milled out the existing headstamp.

Given that the base of the case is pretty thick (you're working well below the web); I doubt you'd get yourself into trouble by truing it up. I do still question if it would make any difference, and I'm pretty sure it wouldn't be worth the effort.

[Dirtlaw]

As an aside, I have taken a case and rotated the base against some oiled wet/dry abrasive paper to remove ejector marks on brass where I got a little aggressive with charges.



I had a similar thought. I was thinking of twisting it on a surface plate or plate glass with a piece of 1500 grit wet/ dry abrasive paper. Very little material would be removed - essentially just a polish with any high spots being made evident (though it wouldn't show if the base was canted.


I've also seen semi-commercial brass that I suspect was Mexican-Matched where they milled out the existing headstamp.

Given that the base of the case is pretty thick (you're working well below the web); I doubt you'd get yourself into trouble by truing it up. I do still question if it would make any difference, and I'm pretty sure it wouldn't be worth the effort.


Agree with all of the above. And I understand that I am being far more picky than I need to be. But darn the variance I see keeps bugging me and I'd like to discover an answer. I guess cats aren't alone when it comes to death by curiosity.

above

[divingin]

But darn the variance I see keeps bugging me and I'd like to discover an answer.

My first step in your shoes would be to move to something a little more precise than the Hornady tool. While useful, it's not the most precise thing out there.

At the very least get their base (sits on the other caliper blade to give you wider seat for the case base), which should alleviate a lot of the canting.

[Dirtlaw]

Part of what motivates me is the fact that the base sitting on the press shell holder is the most fundamental point of reference in the reloading process. Everything is connected to the base.



It's like shooting. A small error at the point the shot is fired tends to lead to a much larger error where the shot lands. Being accurate from the starting point gives you the best chance of being accurate at the end.