Shoulder Bump

[Eraser]

I bought a switch barrel and a go gauge for a Remmington 700 in .223. I got the go gauge to close with just a very light touch.
The gauge measures 1.444 with the Sinclare shoulder gauge. With a piece of tape @.002 for the no go the bolt is no were near closing.
Here's what's confusing me. My twice fired brass shoulder measurement come out at an average of 1.4536. Thats .0096 longer than the go gauge. Yet the fired brass comes out of/ and goes back into the chamber with no effort.

My first thought is the shoulder on the go-gauge (Forster) is different than the one cut in the chamber and they are different then the Sinclare gauge.
This is my load,
Hornady brass
Rem. 7 1/2 primers
22.6g Varget
Berger 73g bthp
Fps 2685- Magneto Speed
Any ideas?

 

[spudgun]

Well, if you just neck size the fired brass. I would not worry about the go/Nogo gauge.

I was once told by a guy I trusted very much, when I was having shoulder issues on resized cases.

Your fire forming to the chamber. You can't get a FL die to do that.

 

[Eraser]

Well, if you just neck size the fired brass. I would not worry about the go/Nogo gauge.

I was once told by a guy I trusted very much, when I was having shoulder issues on resized cases.

Your fire forming to the chamber. You can't get a FL die to do that.

"Well, if you just neck size the fired brass. I would not worry about the go/Nogo gauge."

That just what I did after the first firing.

 

[gunsandgunsmithing]

I bought a switch barrel and a go gauge for a Remmington 700 in .223. I got the go gauge to close with just a very light touch.
The gauge measures 1.444 with the Sinclare shoulder gauge. With a piece of tape @.002 for the no go the bolt is no were near closing.
Here's what's confusing me. My twice fired brass shoulder measurement come out at an average of 1.4536. Thats .0096 longer than the go gauge. Yet the fired brass comes out of/ and goes back into the chamber with no effort.

My first thought is the shoulder on the go-gauge (Forster) is different than the one cut in the chamber and they are different then the Sinclare gauge.
This is my load,
Hornady brass
Rem. 7 1/2 primers
22.6g Varget
Berger 73g bthp
Fps 2685- Magneto Speed
Any ideas?

I think the biggest variable is WHERE on the gage your tool is hitting. Everything has tolerances including the tools we use to measure with. I agree with your suggestion that the angles are slightly different and add to that, the tool you are measuring with probably does not hit exactly at the true datum diameter of neither the case nor the gage. Those are a COMPARATOR, not a tool to give precise headspace measurement. So yes, if it hits at two different points on two different parts, even if one is made to a "standard", it means very little unless/until you figure out the exact difference in all three parts and your measuring device/error. Most gages have a dimension engraved on them. If yours does, how does it compare with your measurement? That engraved dimension should be quite accurate but it is to the actual datum diameter, regardless of angle. Most gages don't have the same angle as the case but it needs to be somewhat close.

 

[BoydAllen]

I bought a switch barrel and a go gauge for a Remmington 700 in .223. I got the go gauge to close with just a very light touch.
The gauge measures 1.444 with the Sinclare shoulder gauge. With a piece of tape @.002 for the no go the bolt is no were near closing.
Here's what's confusing me. My twice fired brass shoulder measurement come out at an average of 1.4536. Thats .0096 longer than the go gauge. Yet the fired brass comes out of/ and goes back into the chamber with no effort.

My first thought is the shoulder on the go-gauge (Forster) is different than the one cut in the chamber and they are different then the Sinclare gauge.
This is my load,
Hornady brass
Rem. 7 1/2 primers
22.6g Varget
Berger 73g bthp
Fps 2685- Magneto Speed
Any ideas?

The Hornady gauge inserts make line contact, which is why I prefer them. there is no possibility of an angle mismatch. When I set up using a fired case, I decap it, and put a piece of Scotch tape on the back, trimming off everything that is not on the flat. As with your GO gauge, that makes it impossible to close the bolt. Then I do a series of small adjustments of the die for each sizing, making sure to wipe all of the case lube off of the case for each trial in the chamber. At the beginning, before I get to my final adjustment, I check the sized case to make sure that the die is reducing its diameters at the shoulder and a little above the extractor groove. The last time I did this, I used the point where very light pressure moving the bolt handle with thumb and one finger let me place it anywhere in its up down range, with the bolt stripped. I used that as my zero point, and with a thousandth bump from there, the handle dropped. With some clearance everywhere around a case and no striker assembly or spring plunger ejector there is nothing to keep it up. For most applications if you are not going to verify your bump for each case, you may want to bump a little more so that none will be tight. Although I do not anneal, I have worked with a friend who had a bump consistency problem with some magnum cases that we were able to solve by annealing just enough to make the bump consistent. For my PPC and other small cases I have not had the problem.

 

[K22]

The purpose of bump gauges is the compare the fired case (primer removed) to the sized case to assess the amount of sizing.

Not sure why you would want to introduce a go gauge into the bump gauge measurement process since I don't see the relevance.

The Sinclair bump gauge indexes off the shoulder whereas the Hornaday and Whidden gauges index off a "datum" line.

 

[gunsandgunsmithing]

The purpose of bump gauges is the compare the fired case (primer removed) to the sized case to assess the amount of sizing.

Not sure why you would want to introduce a go gauge into the bump gauge measurement process since I don't see the relevance.

The Sinclair bump gauge indexes off the shoulder whereas the Hornaday and Whidden gauges index off a "datum" line.

This...
If all gages have to be absolute in shoulder angle, then so does every reamer and every die...with zero tolerance. Look at a reamer print.

 

[M-61]

I look at it still another way. I’m not ‘bumping’ anything if it’s not needed. Needed meaning a hard or tough bolt close as an example.
I consider ‘bumping’ a corrective measure, not a step in reloading.

 

[rjs1230]

I look at it still another way. I’m not ‘bumping’ anything if it’s not needed. Needed meaning a hard or tough bolt close as an example.
I consider ‘bumping’ a corrective measure, not a step in reloading.

^^^^^^^

 

[Clancy]

Neck size if you must, or preferably FL size with 1-3 thou setback. I can’t say I’ve ever had the notion to compare a fired case to a go gauge. Maybe I’m wrong for that?

In Tony Boyer’s book, he mentions that no Reamer cuts a perfect shoulder. That’s about as sound of confirmation as I need, anyway.

 

[Coyotefurharvester]

Your gage is off about 0.029, COMPARING the brass to the SAAMI chamber specs(1.4636-1.4736). Adding your 1.4536+ .0291 -.0096= 1.4731 which is the middle of the SAAMI headspace spec. I don't think this is accidental(chance). So only bump when brass requires more effort to close the bolt than the gage needed(firing pin/spring removed). And use the Sinclair gage for comparison as the chamber is static and the brass changes after firing,cool down,and sizing(spring back). Your fired brass should rechamber fine as it is 0.005 short of max chamber headspace length. Use the spent primer partial seat test to confirm.

 

[Clancy]

Your gage is off about 0.029, COMPARING the brass to the SAAMI chamber specs(1.4636-1.4736). Adding your 1.4536+ .0291 -.0096= 1.4731 which is the middle of the SAAMI headspace spec. I don't think this is accidental(chance). So only bump when brass requires more effort to close the bolt than the gage needed(firing pin/spring removed). And use the Sinclair gage for comparison as the chamber is static and the brass changes after firing,cool down,and sizing(spring back).

We are really lucky Sinclair sells those gauges. I mean, a fired 9mm case works, but for $25 or so, the Sinclair is amazing. I have a full set of shoulder and ogive comparators.

 

[Eraser]

I think the biggest variable is WHERE on the gage your tool is hitting. Everything has tolerances including the tools we use to measure with. I agree with your suggestion that the angles are slightly different and add to that, the tool you are measuring with probably does not hit exactly at the true datum diameter of neither the case nor the gage. Those are a COMPARATOR, not a tool to give precise headspace measurement. So yes, if it hits at two different points on two different parts, even if one is made to a "standard", it means very little unless/until you figure out the exact difference in all three parts and your measuring device/error. Most gages have a dimension engraved on them. If yours does, how does it compare with your measurement? That engraved dimension should be quite accurate but it is to the actual datum diameter, regardless of angle. Most gages don't have the same angle as the case but it needs to be somewhat close.

Thanks for bringing up the gauge dimension, I never thought of looking.
The gauge is marked 1.4636, the comparator measured it at 1.444. So, right off the bat I was off to a bad start.

 

[Eraser]

Your gage is off about 0.029, COMPARING the brass to the SAAMI chamber specs(1.4636-1.4736). Adding your 1.4536+ .0291 -.0096= 1.4731 which is the middle of the SAAMI headspace spec. I don't think this is accidental(chance). So only bump when brass requires more effort to close the bolt than the gage needed(firing pin/spring removed). And use the Sinclair gage for comparison as the chamber is static and the brass changes after firing,cool down,and sizing(spring back). Your fired brass should rechamber fine as it is 0.005 short of max chamber headspace length. Use the spent primer partial seat test to confirm.

After being alerted to the gauge dimension (1.4636) and doing the math as you have shown it, puts me at 1.4632.
Thanks
And what is the spent primer test?

 

[Eraser]

Thank you all for the great help and advice.
I have set up other barrels and have always had to resize and bump after fire forming. When this brass didn't need that I went looking for a problem I didn't have and went about it all wrong besides.
Thanks again.