Mic

[Eagle Eye]

Mic's
Do you use em to measure case shoulder to the base of the cartridge to give the exact SAAMI tolerance readings?

What exactly do you use? Ive seen a digital one (Innovative technologies) out there but reviews aren't great.

Do you neck size/full length resize? How do you know when it's time to bump the shoulder back? Obviously its too late when the round won't chamber anymore


Thank you!

 

[magna19]

I use the RCBS Precision Mic for the calibers I shoot. Got most them on the 1/2 price shelf at H&H over the last several years. I also bump the shoulder .002-.003 with a FL Die each time to ensure all my rounds chamber. Every thing I shoot is factory production used for hunting.

 

[Eagle Eye]

Thanks magna It sounds like you have a good system going.

 

[distantfoe]

http://m.hornady.com/store/Lock-N-Load-Headspace-Kit-With-Body-1-Each/

This will is about as easy as it gets, plus the bodies will do several calibers. When starting out I learned a lot with these. Didn't realize the shoulders got longer until right up to actually bumping the shoulder.

 

[dennishoddy]

I full length resize everything. Never had a problem with the shoulder extending. I've never neck sized only, so I can see where that might be an issue. Wouldn't you just have to run it back through a full length sizing die to correct the problem?

 

[magna19]

I full length resize everything. Never had a problem with the shoulder extending. I've never neck sized only, so I can see where that might be an issue. Wouldn't you just have to run it back through a full length sizing die to correct the problem?

Yes if you properly FL each time for hunting rounds it can save you a problem later on while you might be 200 miles away from home on a cold 8 deg morning deer hunting. Neck sizing only can cause problems when temperature differences in ammo and gun, or when dirt enters chamber on a tough hunt. I just use the chamber mics to help the brass live longer. I like to test my hunting load accuracy. Right now my factory Rem 700 in 7 Rem mag shoots a 168 Berger classic hunter @ 3020 fps with 66.8 grs Reloader 22. Groups consistently go 5 shot 100yds in the .5 to .6 range and sometimes tries to shoot .25 to .4... With nearly 700 down the pipe with minimal shoulder bump I feel the mics help a lot on the brass.

 

[Larry Morgan]

Also note that the Hornady type headspace comparator that clamps to your calipers cannot measure absolute headspace, it can only do relative measurements. It's designed for you to take a fireformed case and use that as the comparison to set the headspace on sized cases. Only way to check against SAAMI spec is to get a case gauge, which I'd highly recommend.

I set mine back about 0.001" after every firing. You can also put me in the column of "bullocks" when told to use a FL sizer as just a neck sizer by backing it out a little (I've had multiple people tell me to do this). Unless the diameter of your chamber in your gun is at min already, the case will grow outward. Unless your FL sizer's diameter happens to be matched to your chamber's diameter, it will shrink the body and make the length grow. My rifle is right at min headspace, plus a thousandth or two. If I take one of my fired cases and run it through the sizer without hitting the shoulder, it will not chamber again until I bump the shoulder back.

 

[Eagle Eye]

Thank you Larry and distantfoe.
I had been using only neck sizer and had a couple of rounds not chamber in my M1 Garand. At the time I was not sure what had happened and could not offer a good explanation as to why it did. Now I know... I've got Mic's and FL dies on order. I will probably set the neck back 0.001 after every firing, but I will also see how much they grow with different charges. I assume hotter charges will result in a bigger shoulder bump than medium/low charges, and the age of the brass (times shot) will also play a role.

 

[turkeyrun]

I always full length resize.

Use RCBS calipers for OAL and trimming cases. I resize a lot of .30-06 and .270 brass to 7x57 or .300WinMag to 7mmRemMag.

 

[Eagle Eye]

When finding the best bullet depth, I can't seem to get the rim of the free bore tool grasped by the extractor. The instructions state that the rim must be grabbed by the extractor. I suppose measurements taken when the extractor did not grab the bore tool will not be accurate. Is that correct?

I am working with an M1 garand.