Comparators

[Bill W]

In the 7mm sight in help thread someone mentioned using a comparator to determine where the body of the bullet begins.

Here's my question:   Do you accept the mfgrs statement that the hole in the 7mm instance is .284 or do you measure it to verify?  Reason I ask is I have a tight neck benchrest gun and I have to turn down the necks to a certain thickness.   What I've observed is just handling the tool warms it up and changes the neck thicknesses I get.  Also I'm old school and that's why I recommended using a micrometer.  Unless they are mishandled they pretty much hold calibration provided it's not a cheap micrometer.

[BULLBLASTER]

Well the hole in the comparator isn't .284 it is smaller to show you where the ogive of the bullet is. It will give you a good datum line to measure length with and is much easier to get a repeatable measurement on the bullet than just using micrometers where you think the ogive may be.

If just holding the tool in your hand changes the thickness an amount you can notice how do you ever deal with any heat in your chamber or barrel or ammo itself?

[Bill W]

BB,  I see you don't shoot benchrest.  If so you'd understand more about heating tools up.  I also assume you trust what the mfgr said about the diameters of the holes in a comparator.  I for one, would want to measure the holes if I was using such a tool.

On bullet diameters and such, I have found that .0015 difference in the diameter of a bullet (and it's fit in the chamber throat) is worth about 15 points in a score match.

[BULLBLASTER]

BB,  I see you don't shoot benchrest.  If so you'd understand more about heating tools up.  I also assume you trust what the mfgr said about the diameters of the holes in a comparator.  I for one, would want to measure the holes if I was using such a tool.

On bullet diameters and such, I have found that .0015 difference in the diameter of a bullet (and it's fit in the chamber throat) is worth about 15 points in a score match.

The hole size in a comparator doesn't matter... all it is for is conparing. I use it when seating bullets to ensure my bto is consistent so I really don't care what the mfr says about the inside diameter of the comparator.
I do understand thermal expansion properties of metal and I understand that it applied to all the metal (barrel, action, case, bulle... all at different rates) not just to your tool.

And your correct I do not shoot benchrest but have no clue what that has to do with a bullet comparator.

[Bill W]

Well, you suggested the guy with the 7mm barrel use a comparator to figure out why his bullet fit all the way into his barrel.   I wondered how that advice would help.

Anyways, the best to you in shooting.

[BULLBLASTER]

Well, you suggested the guy with the 7mm barrel use a comparator to figure out why his bullet fit all the way into his barrel.   I wondered how that advice would help.

Anyways, the best to you in shooting.

Because it would shot where the ogive of the bullet is... also fwiw in the pic you can clearly see the bullet cannuler between the brass and the barrel. And in the other pic it looks to have a recessed crown...
but congrats on starting a thread in the sole attempt to bash and prove me wrong... 

[Bill W]

As I said, the best to you in shooting.  This was not bashing, nor prove you wrong.

[Karl Blanchard]

Bill, based on your opening statement I take it you are not grasping what a comparator is intended for.  It is purely a tool meant to give you a more accurate measurement than using calipers and measurine from the tip of the bullet.   Othing more, nothing less.  In the 7mm thread that bullet has clearly made contact with the barrel at its ogive which sits just in front of the cannelure ring.  There is a clear gap between the casing and the barrel in which you can clearly see the cannelure ring of the bullet. 

Comparator is purely for accurate measurement of OAL, nothing more, nothing less.

[grundy53]

Bill, based on your opening statement I take it you are not grasping what a comparator is intended for.  It is purely a tool meant to give you a more accurate measurement than using calipers and measurine from the tip of the bullet.   Othing more, nothing less.  In the 7mm thread that bullet has clearly made contact with the barrel at its ogive which sits just in front of the cannelure ring.  There is a clear gap between the casing and the barrel in which you can clearly see the cannelure ring of the bullet. 

Comparator is purely for accurate measurement of OAL, nothing more, nothing less.

Sent from my E6782 using Tapatalk

[Bill W]

Bill, based on your opening statement I take it you are not grasping what a comparator is intended for.  It is purely a tool meant to give you a more accurate measurement than using calipers and measurine from the tip of the bullet.   Othing more, nothing less.  In the 7mm thread that bullet has clearly made contact with the barrel at its ogive which sits just in front of the cannelure ring.  There is a clear gap between the casing and the barrel in which you can clearly see the cannelure ring of the bullet. 

Comparator is purely for accurate measurement of OAL, nothing more, nothing less.

I understand what a comparator does but what I was questioning was how it would help the OP in the 7mm barrel problem determine if his muzzle was worn out from improper cleaning habits.    I do not own, nor use a comparator as I used different methods for determining OAL for my loads and rifles.

[Karl Blanchard]

Ok I braved the cold and headed out to the slave yard   comparator contacts the same exact spot every single time allowing you to have a very accurate measurement on seating depth compared to measuring from the tip of the bullet.

[Karl Blanchard]

Bullet clearly not fitting all the way in.

[Bill W]

I'd "like" your last two posts if I could.