How to measure shoulder bump without rcbs precision mic?

[25WSM]

Buzzsaw doing it like this doesn't tell you if your die works properly for your chamber. Just going by feel how do you know if the shoulder length is making contact or shoulder dia. Both will give you the same feel. If you have the tools use them. If you bump .003 and then there is still resistance then your die is leaving a diameter too big somewhere.
Shep

 

[Buzzsaw]

the older i get the less technical i become. or i guess you could call me lazy.

 

[ronstone09]

Howdy,

I use an rcbs precision mic setting my FL die for .30-06
Contemplating getting into a caliber that rcbs does not make a precision mic for
how do I adjust the die to only bump
.001?
Are there other tools out there?
thanks

Go online and get panhandle precision ! He explains all phases including bump and setback ! If you put a caliper on a dollar bill it measures a out 4 thousands, you only want to bump 2 thoslusnds

 

[ronstone09]

Howdy,

I use an rcbs precision mic setting my FL die for .30-06
Contemplating getting into a caliber that rcbs does not make a precision mic for
how do I adjust the die to only bump
.001?
Are there other tools out there?
thanks

I would go o line to Panhandle precision they cover every aspect of reloading including shoulder bump and set back !

 

[marchboom]

I use the Sinclair bump gage insert. It fits the Sinclair and Hornady insert holder. You get the one that matches the shoulder angle of the case, not the caliber. The machining and finish is great.

 

[ronstone09]

Personally I would bump min .002

I agree .001 might be a little tight depending on the chamber

 

[bigedp51]

BUT IT IS NOT ONE size fits all. there are seven or so inserts, but they are not all based on case datum point, just close enough to see shoulder bump.

What I meant was with the RCBS precision mic you have to buy separate gauges for each caliber. And with the Hornady cartridge case headspace gauge one gauge works with all normal calibers. Or one size fits all.

 

[Lionel Boyd Johnson]

To get the most reliable and consistent "feel" when closing the bolt on a resized case; you should first remove the firing pin/spring. Obviously, if you have a claw extractor, insert the case under the lip of the extractor before running it into the chamber. If you have go and no-go headspace gauges that match the caliber of the RCBS Precision Mic, measure them and see what you get. You may be surprised. -Ed

 

[nicholasjohn]

Better photo thats not blocked by photobucket.

Very handy, Sir !!!

 

[nicholasjohn]

Buzzsaw doing it like this doesn't tell you if your die works properly for your chamber. Just going by feel how do you know if the shoulder length is making contact or shoulder dia. Both will give you the same feel. If you have the tools use them. If you bump .003 and then there is still resistance then your die is leaving a diameter too big somewhere.
Shep

Somebody posted a comment here recently about a shoulder bump die pushing the case wall/shoulder juncture out a bit to a larger diameter. Is this an example of what you're suggesting ?

 

[25WSM]

That can happen when the die is slightly too big.
And when your setting up your bump the case will grow slightly before it goes shorter. As the shoulder junction starts to get sized the shoulder will move slightly ahead. Then the next adjustment of about . 003 to . 003 will move your shoulder back. It's a phenomenon that messed with new guys head. They always say to me. I moved the die down but my shoulder got longer. Yup it does right before it's just right.
Shep

 

[CTK]

That can happen when the die is slightly too big.
And when your setting up your bump the case will grow slightly before it goes shorter. As the shoulder junction starts to get sized the shoulder will move slightly ahead. Then the next adjustment of about . 003 to . 003 will move your shoulder back. It's a phenomenon that messed with new guys head. They always say to me. I moved the die down but my shoulder got longer. Yup it does right before it's just right.
Shep

Similar issues still mess with my head and I have successfully reloaded for 10 years. I could not load without the Hornady headspace comparator inserts.

 

[jdyoung]

To get the most reliable and consistent "feel" when closing the bolt on a resized case; you should first remove the firing pin/spring. Obviously, if you have a claw extractor, insert the case under the lip of the extractor before running it into the chamber. If you have go and no-go headspace gauges that match the caliber of the RCBS Precision Mic, measure them and see what you get. You may be surprised. -Ed

Yeah, I do that, ( strip the bolt internals, run resized cart ) and just to check that my "feel" is what I want...... proper spec, I use the Stoney Point /Hornady ( SP owned it first), Headspace Comparator to check. Once set up, it is quicker to use than the RCBS Precision MIc, ( I got impatient threading the RCBS die together so I went to the Stoney Point/ Hornady) but I like the RCBS Mic as it is made of steel and still use it. Belt and Suspenders.

243winxb's device is a clever, least expensive alternative,(especially if its pick-up brass and don't have to buy the pistol).
Could be that is the "Mother" of many such gauges/comparators.

 

[bigedp51]

If you measure a "fired" case with the Hornady gauge and adjust the die for the proper amount of bump there is "NO" feel. The amount of shoulder bump is how much head clearance you have and the bolt face does not touch the rear of the case. Meaning the Hornady type gauges eliminated the need for "feel" closing the bolt.

The ejector and firing pin push the case forward leaving the head clearance or air space between the bolt face and the rear of the case. Meaning you can not "feel" the head clearance or air space.

"FEEL" was what was used before the Hornady type gauges came into being. And the Hornady gauge is far more accurate than guessing by what you "feel". And all you need to remember is there is some brass spring back on a once fired case. Meaning the shoulder of the case is shorter than actual chamber headspace. The basic thumb rule for shoulder bump is .001 to .002 for a bolt action and .003 to .006 for a semi-auto.