Shoulder bump question

[fguffey]

To begin with, there is zero chance you can have .100" headspace and still have the striker hit hard enough to set off the case....firing pin protrusion is typically .060".

As I have said many times there has to be something about pulling the trigger and the bullet leaving the barrel reloaders do not understand.

Again, I chambered a round and pulled the trigger knowing the shoulder of the case was .127" from the shoulder of the chamber, in some circles it is said I had .127" clearance but no one would say I had .100 head space. "What does that mean?

F. Guffey

 

[Richard Jones]

Your trying to get the proper fit to your chamber not a SAAMI spec.

again, this. Your chamber may BE SAAMI, but it may not.

 

[ttfreestyle]

Wasn't the ops question answered in the first 2 or 3 replys?

 

[Richard Jones]

Wasn't the ops question answered in the first 2 or 3 replys?

So sorry, sir, perhaps it was.

 

[msinc]

The OP is not talking about headspace of a gun. He was asking about his cases being new and .007 shorter then fired. This is common with new brass or factory ammo. Yes headspace on a gun can be dangerous and I did not debate this. I just stated facts of new cases and ammo. Matt

I just had a quick look at my go gauge for the 308...the minimum headspace length on the gauge and also what any good gunsmith would set headspace at if he was rebarreling a rifle is 1.630" That is SAMMI headspace for a go gauge. New cases should be measuring with a tolerance of +.000" - .004" {1.630" to 1.626"} to meet SAMMI specs and BE SAFE TO SHOOT in a properly chambered gun. We all know that they could be a few thou longer and the bolt will still close, but that's not the issue. If in fact the OP is measuring correctly then at these measured sizes:
To quote the OP...
"With my comparitor, virgin .308WIN Lapua cases and factory ammo seem to measure at 1.616", and my fired cases measure 1.623" - so am I aiming for 1.621-1.622"?"

He has brass that is .014 under size and they are stretching in the chamber .007" to leave them still .007" under size. Pretty simple math. Further, headspace "of a gun" and headspace of the ammo really is one in the same if that ammo is being used in that gun. After all, it is the fit of the ammo in a particular chamber that counts, no????? My point is that if 1.630" is minimum chamber size {plus possible .004" more} and he hits his "target" size of 1.621" then he still has at the very least .009" headspace when this ammo is in his chamber.
Again, blowing a shoulder out or fire forming in a properly headspaced chamber with properly sized ammo IS NOT THE SAME as firing ammo with excess headspace. So I ask again...exactly how much headspace, not brass moving when being properly fire formed, do you believe is no problem or safe????? Please tell us???
My guess, and it is probably correct, is that the OP IS NOT setting his comparator with a go gauge and I also doubt he is not measuring his cases with some sort of a pre-set device like the RCBS case mic. So he cant be as far under as he is saying, but it is still not safe. I have seen a lot of rifles and checked the chambers on them to find several mistakes, but never have I seen a factory rifle with a chamber that was not chambered deep enough or even very far off the mark at all, especially deeper than what would be safe and I'd bet that if I started measuring factory ammo I would find the same thing. Rimless ammo that is too short at the shoulder creates an excess headspace condition {I guess if you don't get this concept then I cant help you!!!!}...having a rifle that is chambered correctly doesn't get the ammo company off the hook for a lawsuit if the gun blows up due to "short" shoulder length cases that blow the gun and hurt somebody.

 

[Webster]

Wasn't the ops question answered in the first 2 or 3 replys?

True but no-one believes it. 47 replies. FGUFFEY says he is the only one that understands anything.

 

[dedogs]

FGUFFEY says he is the only one that understands anything

Yes he does but don't you find it odd that nobody understands Guffey? When I was growing up if somone called you an ass, well that was just one person's opinion. If two people called you an ass it might get you to thinking. However if three people called you an ass , welllll... dedogs

 

[msinc]

we all have our own "special" way of explaining things or getting our point across. Might want to cut ol' Guff some slack...I am as guilty of it as anyone. Somebody quick!!! Call Ripley's!!!!!

 

[msinc]

from SheepDog:
"You don't need to move the shoulder back until it interferes with the closing of the bolt."
+1

My opinion is it is not a required step in reloading UNLESS you experience the above.

Yeah, but don't you guys find that some rifles shoot best with neck or partial neck sized cases and then you get that one that wants them full length sized for some reason????

 

[dedogs]

we all have our own "special" way of explaining things or getting our point across. Might want to cut ol' Guff some slack

Why? Guffry constantly belittles and berates the other members of this forum, calling us all ignorant of the proper methods of doing things, but refuses to describe how he goes about certain processes in ways that we ignoramuses can understand! dedogs

 

[msinc]

Why? Guffry constantly belittles and berates the other members of this forum, calling us all ignorant of the proper methods of doing things, but refuses to describe how he goes about certain processes in ways that we ignoramuses can understand! dedogs

I understand...I didn't say that anyone paid any attention to what he says or even believes him. I think most people that read his threads wonder if his phone is changing what he types. I put the word "special" in quotes for a reason.

 

[dedogs]

I put the word "special" in quotes for a reason

Got it.

 

['Freak]

What’s really scary is thinkin’ I almost understood much of what that guffey dude tried to again explain to all us ignoramuses back at #37. And then there’s the matter of I never officially finished high school …

 

[LHSmith]

Yeah, but don't you guys find that some rifles shoot best with neck or partial neck sized cases and then you get that one that wants them full length sized for some reason????

If one measures accuracy in the aggregate....that is multiple groups shot in different conditions (using wind reading skills) on different outings then averaged out...then NO. Accuracy is the result of eliminating as many variables as possible. Only FL sizing (with a die suitable to your chamber) will provide consistent dimensioned cases....if started from the same lot. After several firings, depending on the pressures created by your load, annealing may be necessary to attain consistency.
I'd venture to say that not many non-competitors on this forum understand the concept of baseing their rifles accuracy on it's aggregate.....more like pick and choose among a minimal number of groups fired on an outing with non-benign conditions.
The exception to this is if one chooses to shoot a load in the lower nodes where pressures never allow the case to require any bump....a place that the barrels optimum accuracy is seldom reached.

 

[swadiver]

wish you had used a different visual on this one

 

[fguffey]

My guess, and it is probably correct, is that the OP IS NOT setting his comparator with a go gauge and I also doubt he is not measuring his cases with some sort of a pre-set device like the RCBS case mic. So he cant be as far under as he is saying

And I would say if he is using a comparator it would not matter. Problem is: he is trying to tie SAAMI specifications to a tool that is notorious for error because the tool has a case friendly datum. Something no one understands is I use a non friendly datum, my datum's use a very sharp edge and with no bevel. Meaning if the hole is .375" with a sharp edge it is absolute. Back to Hornady/Sinclair; relosaders assume the measurements can be transferred to SAAMI specifications, if the hole called the datum has a radius the .375" datum is below the surface and unlike Wilson Hornady/Sinclair did not correct the discrepancy/error.

Measure before and again after: The Wilson case gage is a datum based tool, the datum in the Wilson case gage has a bevel/radius, the problem with a radius on the datum is corrected when Wilson grinds the top of the case gage with the two steps. And there is the problem with instructions. Wilson recommended using a straight edge over the head of the case above the gage when determining case length. Most reloaders used their thumb, or daylight and then in the beginning reloaders called the Wilson case gage a drop-in gage, not me I use a feeler gage with the straight edge. I can only guess some are mechanically challenged.

Back to the datum in the Wilson case gage; a reloader can use the case gage as a comparator or a case length gage.

F. Guffey

 

[fguffey]

ttfreestyle said: ↑

Wasn't the ops question answered in the first 2 or 3 replys?

No, one of the first replies was from Webster, I can only guess he jumped out in to the fast lane and then missed a gear, or something. In my opinion the OP deserves a better answer because it is evident he needs a lot of blanks filled in.

F. Guffey

 

[msinc]

And I would say if he is using a comparator it would not matter. Problem is: he is trying to tie SAAMI specifications to a tool that is notorious for error because the tool has a case friendly datum. Something no one understands is I use a non friendly datum, my datum's use a very sharp edge and with no bevel. Meaning if the hole is .375" with a sharp edge it is absolute. Back to Hornady/Sinclair; relosaders assume the measurements can be transferred to SAAMI specifications, if the hole called the datum has a radius the .375" datum is below the surface and unlike Wilson Hornady/Sinclair did not correct the discrepancy/error.

Measure before and again after: The Wilson case gage is a datum based tool, the datum in the Wilson case gage has a bevel/radius, the problem with a radius on the datum is corrected when Wilson grinds the top of the case gage with the two steps. And there is the problem with instructions. Wilson recommended using a straight edge over the head of the case above the gage when determining case length. Most reloaders used their thumb, or daylight and then in the beginning reloaders called the Wilson case gage a drop-in gage, not me I use a feeler gage with the straight edge. I can only guess some are mechanically challenged.

Back to the datum in the Wilson case gage; a reloader can use the case gage as a comparator or a case length gage.

F. Guffey

I get what you are saying about the comparator edge...I use the Stoney Point set up, but I don't exactly trust aluminum to hold a good tolerance. It seemed like to me that with aluminum the least little nick or gunch mark on that critical edge would make the tool read off...so, most of mine I have turned myself on my lathe. I finished the outside with a hone to get the best edge I thought I could. It's a double edged sword because if it's too sharp and perfect it will cut into the brass.
One other thing I do is to avoid a bunch of different end pieces I just pick one that has enough diameter to hit somewhere on the shoulder and set it with a go gauge. Kind of making or using my own datum line. I figure as long as it is set with the gauge to start with who cares if it's .375 or .400 {just as an example}??? I haven't run into any problems yet.

"I can only guess some are mechanically challenged."

Ta hell you say?????

 

[fguffey]

"I can only guess some are mechanically challenged."

Ta hell you say?????

When using a comparator I do not care what the diameter is, the hole has to be larger in diameter than the case neck and smaller in diameter than the case body/shoulder juncture. If I am using a datum it has to have a sharp edge, I have no problem leaving the imprint if the datum on the shoulder, again, there is no datum line, in the beginning there was a line and an arrow, and reloaders claimed they understood.

F. Guffey

 

[ireload2]

You have to care what the diameter is otherwise if the shoulder angle is off you will have an error - I guarantee....
I have asked you many times if you know what ASME Y14.5 is. Apparently you don't and you don't want to know because it would interfere with your riddling.
ASME Y14.5 is the US national standard for dimensioning and tolerancing of drawings, including datum and datum structure definitions. It the document that controls the conventions for the SAAMI and other industry's engineering drawings. This standard is pretty much adhered to by all significant industry in the US including the automotive, aerospace, medical components and semiconductor.

When using a comparator I do not care what the diameter is, the hole has to be larger in diameter than the case neck and smaller in diameter than the case body/shoulder juncture. If I am using a datum it has to have a sharp edge, I have no problem leaving the imprint if the datum on the shoulder, again, there is no datum line, in the beginning there was a line and an arrow, and reloaders claimed they understood.

F. Guffey