Reply With QuoteDatum is .400" Take a 40 S&W or 10MM brass. Remove the primer. Place 40 case mouth on fired 308 shoulder. Measure. Compare to sized.
This is my comparitor.
Looking for thoughts on these 3 tools I'm sure there's pros and cons to them all..wanting to use to help set size die up so I don't oversize the brass..read about .002 is all that's needed to bump the shoulder back on bolt guns. around .005 for auto.. going to be doing 308 ..starting with new brass hornady match and know it needs to be fired formed first, before getting the reading on the shoulder. my plan on this is fire form the brass get reading then neck size only for 2 rds and then see if I need to bump shoulder back.would like to use the hornady gage for the simplicity of it.but heard the bushings are soft alum and wear easy giving false readings. rcbs sounds like it is a little loose threading of the 2 halfs and a little more complicated the Larry wilson on the upper price scale .just wandering from you all what u use...I don't shoot comp or anything just looking for proper technic. and to not over work the brass.thanks to you all...
Datum is .400" Take a 40 S&W or 10MM brass. Remove the primer. Place 40 case mouth on fired 308 shoulder. Measure. Compare to sized.
This is my comparitor.
The RCBS is marked specifically for that cartridge and is accurate. The part of the gauge that measures base to ogive is a weak link. It is time consuming to use on large batches of sized brass.
The Hornady provides you with quick accurate reference information for base to shoulder and with additional components can measure base to ogive. There are a couple of very accurate ways to establish the needed dimension. You can double up on the bullet comparitor sleeves and measure the bearing length of your bullets.
The Wilson tool is a very good Case OAL tool and base to shoulder reference tool. It does not have a provision for base to ogive measurement. Fast and easy.
243winxb method is adequate for base to shoulder reference only. If you just want to measure base to shoulder with calipers, consider this to get you started.
How deep do you want to go down the rabbit hole?
Interesting..I have the hornady bullit comparitor allready and the horndy chamber oal to measure to the lands.thats interesting on the 40 cal case..I assume that is a new unfired case.
The RCBS Precision Mic is designed for only one caliber and the Hornady cartridge case headspace gauge will fit any cartridge.
I prefer the Hornady gauge used with a digital vernier caliper with big numbers for old eyes.
Below a Colt 5.56 Field gauge at 1.4736
Below the same headspace gauge in a adjusted Hornady gauge at 1.4735
Below a "fired" Lake City 5.56 case from my AR15 that gives me a idea what the actual headspace is minus brass spring back.
I then use this reading to adjust my full length die for .003 shoulder bump.
I prefer the Hornady gauge because you can spin the case with your fingers and get more accurate readings.
With the RCBS Precision Mic you can't spin the case to center it and you get variations in the readings.
Below my RCBS Precission Mic and you can only use it with the .308 and .243. You have to open and close the gauge several times to get the case to center and get the shortest reading.
Below a fired .308/7.62 case in a Dillon case gauge, this case is a once fired Lake City case and fired in a military chamber.
Below the same case in a JP Enterprise case gauge, and this gauge is closer to minimum SAAMI diameter.
Meaning if the resized case fits in the JP Enterprise gauge it will fit in any chamber. And the Dillon gauge is larger in diameter and only checks shoulder dimensions.
Bottom line, if you buy bulk once fired Lake City brass that was fired in larger diameter chambers the JP Enterprise gauge checks case diameter. After sizing you are dealing with brass spring back and range pickup brass or once fired military brass may not chamber in your rifle. So all my once fired Lake City cases get a plop test in the JP Enterprise gauge to insure the case will chamber.
If all your new cases were fired in your rifle I recommend the Hornady gauge. If you are a cheap bastard like me and buy bulk once fired Lake City 7.62 cases I recommend The JP Enterprise gauge and possibly a small base die if the sized cases do not fit in this gauge.
Excellent right up with illustration you have there , thanks for your time and input.I will probably go with the hornady gage to use on the bolt gun..as i only want to move the shoulder about .002 or so when i need to .I have a wilson oal gage in 223 that I use on the ar because of range brass and running 2 rifles.i just take them back to factory specs..1 ar is a varmit version with a whiteoak armory barrel when I get the gages in the hornady kit I might tinker with the case headspace in it.i like the way the hornady gage works didn't know about durability Or repeated use...thanks againOriginally Posted by bigedp51
The RCBS Precision Mic is designed for only one caliber and the Hornady cartridge case headspace gauge will fit any cartridge.
I prefer the Hornady gauge used with a digital vernier caliper with big numbers for old eyes.
Below a Colt 5.56 Field gauge at 1.4736
Below the same headspace gauge in a adjusted Hornady gauge at 1.4735
Below a "fired" Lake City 5.56 case from my AR15 that give me a idea what the actual headspace is minus brass spring back.
I then use this reading to adjust my full length die for .003 shoulder bump.
I prefer the Hornady gauge because you can spin the case with your fingers and get more accurate readings.
With the RCBS Precision Mic you can't spin the case to center it and you get variations in the readings.
Below my RCBS Precission Mic and you can only use it with the .308 and .243. You have to open and close the gauge several times to get the case to center and get the shortest reading.
Below a fired .308/7.62 case in a Dillon case gauge, this case is a once fired Lake City case and fired in a military chamber.
Below the same case in a JP Enterprise case gauge, and this gauge is closer to minimum SAAMI diameter.
Meaning if the resized case fits in the JP Enterprise gauge it will fit in any chamber. And the Dillon gauge is larger in diameter and only checks shoulder dimensions.
Bottom line, if you buy bulk once fired Lake City brass that was fired in larger diameter chambers the JP Enterprise gauge checks case diameter. After sizing you are dealing with brass spring back and range pickup brass or once fired military brass may not chamber in your rifle.
69gen1
Have you ever heard the expression "The cartridge should fit the chamber like a rat turd in a violin case" or why the majority of competitive shooters full length resize.
Below Kevin Thomas of Team Lapua USA and who before joining the Lapua team also worked in the Sierra Ballistic Test Laboratory.
Below Erik Cortina of Team Lapua USA.
Good vid..makes sinse ..just measure the shoulder set the die69gen1
Have you ever heard the expression "The cartridge should fit the chamber like a rat turd in a violin case" or why the majority of competitive shooters full length resize.
Below Kevin Thomas of Team Lapua USA and who before joining the Lapua team also worked in the Sierra Ballistic Test Laboratory.
Below Erik Cortina of Team Lapua USA.
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