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Thread: Tikka T3 Lite 300WSM & RCBS Precision Mic

  1. #1

    Default Tikka T3 Lite 300WSM & RCBS Precision Mic

    Just wanted to start a thread and say thanks for all of the information I have been learning on here!

    I am back in AK and got the reloading bench I built dusted off and ready to go. Reading through all of the information on here I ran across a thread about the precision mic (I think by Stid). I immediately ordered one as well as took the forums advice and bought a limbsaver recoil pad for my rifle.

    Tonight I went out and took some measurements using this tool. If I am reading it right, the base measurement for the freebore of my rifle is .041 read off of the tool, not by measuring the COAL with a caliper. The maximum I can seat a 180 grain accubond and still have the cartridge fit in the magazine is -.041. This gives the cartridge an OAL of 2.897 with the bullet sitting off the lands .082.

    For reference, I purchased 1 box of Nosler Custom 180 grain accubond ammunition. The COAL is 2.807 and it is seated so deep the precision mic cannot read it because it goes off the scale before contacting the bullet.

    I was suprised to learn just how far off the lands I will be seating my bullets and still have them fit in the magazine. Guess I will not be using Berger's method using several different seating depths to find the greatest accuracy in your rifle with their bullet. I am waiting for my scope and rings to arrive so I have atleast a week to load up all the test loads I need to take to the range! I am going to take more measurements tomorrow using 165 grain accubonds and see if I can seat them closer to the lands.

    To summarize: This tool is awesome to use to figure out how deep to set your seating die. I purchased a Hornady New Dimension die set and the Microjust seating stem to go with it. I can't say enough good things about the microjust! Seat one bullet, measure the cartridge with the precision mic and simply turn the required number of thousandths to get the right seating depth!

  2. #2

    Default Pictures of Precision Mic

    I wanted to put some pictures on here showing how I am using the Precision Mic. If I am doing anything wrong please let me know!

    One of the pictures shows the dummy round with the bullet and nylon connector pushed out. There is a set screw in the nylon which you tighten so it will slide but have a fair amount of friction holding it in place while doing so. You chamber the dummy round inside your rifle which pushes it back towards the cartridge rim so you can measure it with the mic for a freebore measurement of where a round will contact the lands in your rifle.

    Next I started experimenting by seating 180 grain accubonds in a case with no powder or primer. After seating them to the max my magazine would fit I measured the cartridge with the precision mic. In the picture is the round with no primer or powder. The measurement can be read as either +.009 or -.041

    Some interesting observations I made today: I am using an RCBS rockchucker supreme. After loading live rounds without changing any settings from the night before here are the measurements.
    -.049, -.052, -.056, -.053, -.051, -.054 = Average -.0525

    With the positive .041 freebore measured from the dummy round I should have my bullets off the lands approximately .0935 and average COAL of 2.885

    I am not sure why the measurement changed from a round with no powder and primer to a live round. In any case, I am going with it. I also thought it was interesting how much each round varied when measured with the mic. I use a firm press on the ram with usually a second firm press at the bottom.
    Attached Thumbnails Attached Thumbnails Extended.JPG   Retracted.JPG  

  3. #3
    Moderator stid2677's Avatar
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    Default

    You want to make sure that you are using the correct tool for each measuring operation.
    The cylinder with the large hole in the end is for measuring freebore and the one with the small hole is for seating depth.

    If you are in the Fairbanks area I would be happy to help you out. I noticed your handle and was wondering if you are a scout helicopter mechanic?? I worked on OH-58Ds for many years.

    I too have noticed some deviation while running my ammo through my press. I measure almost every round now that I have started using the Precision Mic and I have noticed an improvement in my groups.

    The key to reloading is to do everything the same, over and over. Same pressure when using your press, and when taking measurements.

    Good Luck

    Steve

  4. #4

    Default

    Hey Stid,

    I am using the barrel nut with the small hole. The one with the large hole is used to take some measurements I don't quite understand yet. Now that I think I have the freebore measurement figured out I have the instructions out reading through headspace. The problem is I don't have any fired cases to measure yet. I am going to measure an unfired, full length resized case for future reference.

    I don't see an option to private message you. Is that disabled until I get a certain post count?

  5. #5
    Moderator stid2677's Avatar
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    Default

    Quote Originally Posted by 58D View Post
    Hey Stid,

    I am using the barrel nut with the small hole. The one with the large hole is used to take some measurements I don't quite understand yet. Now that I think I have the freebore measurement figured out I have the instructions out reading through headspace. The problem is I don't have any fired cases to measure yet. I am going to measure an unfired, full length resized case for future reference.

    I don't see an option to private message you. Is that disabled until I get a certain post count?
    We had to limit PMs for new members because of all the spam PMs we were getting.
    I will get PMs turned on for you.

    The headspace tool will help you setup your resizing die. With .000 being SAMI spec. Once you fire a round, the brass will expand to fill your chamber, the fired brass can be measured and you will know what the headspace is on your rifle. Using that number resize your brass .001 to .002 shorter to ensure they will cycle.

    Steve

  6. #6

    Default

    Thanks Stid,

    I sent you an email.

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