How to measure shoulder bump without rcbs precision mic?

[Jed Eckert]

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

 

[Jud96]

You can get the Hornady headspace comparator gauges and use those the measure the cartridge base to shoulder datum line. Measure a fired case then adjust the die until you achieve your .001 shoulder bump.

 

[Horse1]

You can get a generic digital headspace measurement tool from Innovative Technologies, scroll down to the 2nd item available:

Innovative Technologies

 

[243winxb]

To compare fired to sized brass, you just need a case that touches near the middle of the shoulder. Remove primer, square case mouth.

 

[L.Sherm]

Personally I would bump min .002

 

[243winxb]

Better photo thats not blocked by photobucket.

 

[bigedp51]

243winxb, below is a .40 S&W case on a .223 case, now what do I do. (a "little" case humor)

Wait a minute, I have the Hornady cartridge case headspace gauge that works on any rifle case. And you can even calibrate it to read actual headspace.

Below a Colt 5.56 Field gauge at 1.4736

Below the same Colt Field gauge in my adjusted Hornady gauge.

Below a "FIRED" Lake City 5.56 case in my Hornady gauge.

Below my RCBS .308 Precision Mic I haven't used since I got the Hornady gauge.

Advantage, the Hornady gauge because one size fits all.

 

[Jed Eckert]

Ok
I'll bump a little more
Now some hornady tools to acquire
Thanks a bunch to everybody

 

[25WSM]

The reasoning behind .002 to.003 is because you get various spring backs on your sized cases. If you only do .001 and the brass stays perfectly put your good. But if it springs back then it's not going to have clearence. Anytime you feel the bolt closing hard on a brass there is going to be verticle in your group. By going to .002 or .003 you still have clearence if you get a few cases that spring back a little. I always use.003 myself. I know a current world record holder that bumps .008. he likes his brass loose.
It obviously works for him.
Shep

 

[rsmithsr]

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.

Advantage, the Hornady gauge because one size fits all.

 

[Alibiiv]

To compare fired to sized brass, you just need a case that touches near the middle of the shoulder. Remove primer, square case mouth. View attachment 192296

Thanks for sharing this one, I will have to try this.

 

[misterc01]

Normally I use the RCBS Precision Mic. And I have both the Hornady and Sinclair comparators, take at least 10 readings with each, then average them individually, and have two references. I also have a Willis Innovative technologies Digital Gauge as another reference source. I recently picked up a Forster Datum Dial kit and suspect it will give me fourth tool. I am able to get pretty close with any/or all of these. And yeah, I am a bit of a gadget freak!

 

[TX Badger]

I use the method that Jim See posted somewhere. I resize, put a piece of scotch tape on the case head, and try to chamber the case. You have to work the die down gradually. When the bolt will close on the case with tape on the head, you have your clearance.

Note, test each adjustment on a different case to prevent work hardening. Then once the die is set, set the shoulder back on all the test cases so they are only sized twice.

 

[Buzzsaw]

Ok, I'll get yelled at for this. I have both tools, use neither. I will size and chamber, size and chamber the case till bolt closes with very little or no resistance. Lock the die, your ready to resize. Simple.

MOST important is DO NOT over lube cases when sizing, Hopefully you are using Redding FL dies with their carbide sizer button.