COAL gauge question
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  1. #1
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    Default COAL gauge question

    I have asked this on the accurate shooter forum with no replies, so bear with me. I understand how the inserts for say, a Hornady COAL comparator gauge may be a different ID than what you would expect as a function to work across a lot off different bullet shapes. In my case, I am using a 6xc with 115 DTACS (dead nuts .243 on the bearing surface) and thought it odd that the gauge insert diameters were way under, .239, .2395 or over .2435 and never hit the same spot on the bullet as my Stony Point style gauge indicated the ogive hitting the lands.

    My question is, should I go ahead and ream the insert to .243 or maybe .2425, so that it hits as close as possible to where the chamber indicates the rifling starts? That way I have a more accurate measurement or am I spinning my wheels?

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    Quote Originally Posted by dwebster View Post
    I have asked this on the accurate shooter forum with no replies, so bear with me. I understand how the inserts for say, a Hornady COAL comparator gauge may be a different ID than what you would expect as a function to work across a lot off different bullet shapes. In my case, I am using a 6xc with 115 DTACS (dead nuts .243 on the bearing surface) and thought it odd that the gauge insert diameters were way under, .239, .2395 or over .2435 and never hit the same spot on the bullet as my Stony Point style gauge indicated the ogive hitting the lands.

    My question is, should I go ahead and ream the insert to .243 or maybe .2425, so that it hits as close as possible to where the chamber indicates the rifling starts? That way I have a more accurate measurement or am I spinning my wheels?

    I guessed I missed you on Accurate Shooter. Did you not machine a Gizzy? Run your reamer into a small part of a barrel drop. Using that you can measure a loaded round in your Gizzy. Start long and keep seating as you measure. This will tell you your bullet ogive to base measurement.

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    Default

    I made one by boring a 1.5 deg taper to roughly bullet dia at the face. *Roughly*. It doesn't really matter if its perfect, you only care where it touches the ogive. I tried making a universal with a bigger opening, but at some point it catches the neck of the case instead.

    I kinda think a bit off on the angle doesn't make much difference either. I doubt the throat in the barrel stays the same angle as it erodes.

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    Default

    Having heard about as many different names/definitions for a gizzy/gizmo, etc. as there are gunsmiths, which one are you referring too? I made a shoulder bump gauge from a barrel stub to measure my shoulder set back when sizing. I have also heard of them called a gizzy when referring to a bullet seating comparator gauge, like the inserts I was referencing. After I posted the original post, I decided to go ahead and make up a gauge with the same throat as I used for my barrel and set things up to seat with that as a gauge instead of the commercially produced comparator inserts. I have been reloading and shooting for a long time but never went as deep into ammo prep as I have recently. I was surprised, and perhaps should not have been, to see a lot of the tools I have used over the years are not as close to "spec" as I always thought they were. I was always of the opinion that my time was better spent behind the rifle as opposed to chasing perfection at the loading bench. However, I have seen more improvements with better assembled ammo lately than I have from practice alone.

  5. #5
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    Quote Originally Posted by dwebster View Post
    Having heard about as many different names/definitions for a gizzy/gizmo, etc. as there are gunsmiths, which one are you referring too? I made a shoulder bump gauge from a barrel stub to measure my shoulder set back when sizing. I have also heard of them called a gizzy when referring to a bullet seating comparator gauge, like the inserts I was referencing. After I posted the original post, I decided to go ahead and make up a gauge with the same throat as I used for my barrel and set things up to seat with that as a gauge instead of the commercially produced comparator inserts. I have been reloading and shooting for a long time but never went as deep into ammo prep as I have recently. I was surprised, and perhaps should not have been, to see a lot of the tools I have used over the years are not as close to "spec" as I always thought they were. I was always of the opinion that my time was better spent behind the rifle as opposed to chasing perfection at the loading bench. However, I have seen more improvements with better assembled ammo lately than I have from practice alone.



    Been away. Yes you can use it as a "bump" gauge and to measure and adjust your OAL or


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