Re: Bullet Diameter Measuring Tool - Finally Finished

[dkhunt14]

Re: Bullet Diameter Measuring Tool

In my testing with a 240 Sierra with a 308 Baer a .0002 fatter bullet was 6 inches or more up out of group at 1000 yards. This was shot with a 80 pound heavy gun. I use bushings to measure. The diameter was more critical than the ogive to bearing or total OAL. Also some lots of 240 Sierras were really good and some were really bad. Matt

 

[jlow]

Re: Bullet Diameter Measuring Tool

In general, I like the idea of measuring bullet diameter for the reasons already mentioned. My question is what have you seen in terms of variability?

I’ve done some measurement of 175 grain SMKs and in a 24 bullet sample, I saw an average diameter of 0.30817” with a high of 0.30825” and a low of 0.30810”, so a ES of about 000015” which is not much and probably within the error of the measurement method which is with that digital Mito micrometer I mentioned earlier.

 

[jlow]

Re: Bullet Diameter Measuring Tool

I would agree with that which is why I ask what the variance has been observed.

I guess to me there is a difference between building a tool to weed out bad stuff even when they are rare vs. weeding out stuff that potentially could exist but no one has ever seen….

 

[jlow]

Re: Bullet Diameter Measuring Tool

Thanks! Yes, I missed it... :-[

 

[PMA3]

Re: Bullet Diameter Measuring Tool

danny....thanks for the contact info.
jfseaman...let us know if you put something together.
matt... your findings seem to be consistent with 338 mollett; thicker bullets shoot higher at 1000 yds.
jlow....I know some guys who have found the 6MM 105 hybrids to vary from .2434"-.2439"
dmoran... I tried locally but have yet to find someone who can/wants to do the tool...would like to turn the concept
into reality.

To all....thank you for the valuable input...if I can get someone to make the tool, I will post the info.

 

[jlow]

Re: Bullet Diameter Measuring Tool

Jlow -

You have one to many zero's in your post above. You have it 000015, and is actually 00015.
( .30825 - .30810 = 0.00015" )

Donovan

Sorry, must be getting tired and mis counting the zeros.... Glad to see someone is more anal than I am! ;D

 

[DanConzo]

Re: Bullet Diameter Measuring Tool

I've seen other shooters using Comparator Micrometers usually by Mahr but also other makes like Mitouyo, etc. I notice that Sierra always show in their Manuals since the first edition inspecting bullets with these. They are expensive though, but probably faster than a micrometer.

 

[ReedG]

Re: Bullet Diameter Measuring Tool

A good micrometer in a holding stand or small desk vise is a fast as it gets. I use several empty bullet boxes and mark them with the different diameter numbers. Mic a bullet, read the diameter, put the bullet in the proper box. Don't think it takes 10 seconds.

 

[jlow]

Re: Bullet Diameter Measuring Tool

A good micrometer in a holding stand or small desk vise is a fast as it gets. I use several empty bullet boxes and mark them with the different diameter numbers. Mic a bullet, read the diameter, put the bullet in the proper box. Don't think it takes 10 seconds.

I like it and have similar experience. The advantage to this system is that you are actually binning the bullets instead of making them good or bad. Since diameter diffference affect MV, then bullets in the same bin would have close MVs.

 

[DanConzo]

Re: Bullet Diameter Measuring Tool

An old fashion bullet spinner works good too. Hart, Dewey and others used to make them.

 

[DanConzo]

Re: Bullet Diameter Measuring Tool

Bushings, micrometers or other--they all will work, and some can use a regular micrometer pretty efficient.

 

[Erik Cortina]

Re: Bullet Diameter Measuring Tool

What about a V block with a .0001" indicator on a stand. Slide the bullet between the V block and the indicator stem and look at the reading on the indicator. You can sort bullets very easily that way.

 

[aj300mag]

Re: Bullet Diameter Measuring Tool

What about a V block with a .0001" indicator on a stand. Slide the bullet between the V block and the indicator stem and look at the reading on the indicator. You can sort bullets very easily that way.

You're close Erik, real close.

Back when I had to grind multiple parts and hold a .0002" tolerance I'd set up a snap gage. Same concept you're talking about but it wasn't a "V" block. The anvil is flat. Takes seconds to measure a part.

 

[jfseaman]

Re: Bullet Diameter Measuring Tool

What about a V block with a .0001" indicator on a stand. Slide the bullet between the V block and the indicator stem and look at the reading on the indicator. You can sort bullets very easily that way.

You're close Erik, real close.

Back when I had to grind multiple parts and hold a .0002" tolerance I'd set up a snap gage. Same concept you're talking about but it wasn't a "V" block. The anvil is flat. Takes seconds to measure a part.

That's to easy. Forget bushings.

 

[jelrod1]

Re: Bullet Diameter Measuring Tool

The only real advantage to this type of sorter to me would be if it sat up a little higher off the table and had a bin under each coresponding hole so you didn't have to handle them again. I could make this for you if you want to persue it. Could either buy the size reamers you want and make out of 4140 prehard or make out of A2 and harden it, then EDM the holes in it.

Personally I think measuring with the right tool would be just as fast and would give you actuals without the chance of sticking one in a hole. I use this type micrometer beside the caliper to sort parts or a snap gage. It is spring loaded and will read tenths on the indicator.

 

[DanConzo]

Re: Bullet Diameter Measuring Tool

That's the comparator (indicating) micrometer I was talking about, some have an adjustable platform to place whatever you are measuring on. Seems like a great tool for comparing diameters of bullets. Other methods seem to work too.That's one nice tool.

 

[dannyjbiggs]

Re: Bullet Diameter Measuring Tool

What about a V block with a .0001" indicator on a stand. Slide the bullet between the V block and the indicator stem and look at the reading on the indicator. You can sort bullets very easily that way.

+1

Danny Biggs

 

[jlow]

Re: Bullet Diameter Measuring Tool

This is what would use. If you are picky about where you measure, you can clamp a stop on it.

 

[338 Mollett]

Re: Bullet Diameter Measuring Tool

Good idea Eric,with the V block you can slide the bullet any where and measure it.Make a stop and measure base to ogive even.

 

[jlow]

Re: Bullet Diameter Measuring Tool

I have a Starrett mic that reads to .0001" but measuring each bullet and measuring the exact same spot (pressure ring) each time would be a chore for sorting 500 bullets at a time. The tool I'm looking for would be in .0001"
(Example .2433") .... you would slide the bullet into the hole(s) and they would act as a GO/NO GO gauge...if they don't fit the .2433" hole but slide through the .2435" hole, then I would know the approx. diameter and how to sort them fairly quickly.

I can tell you from personal experience using the Mito micrometer mounted on a stand measuring bullet diameters that it is much easier, faster, and safer (for the bullets) than the method you describe above.

With the micrometer, it's a simple matter of putting the bullets between the jaws and make a slight turn of the ratchet stop thimble. You put a small and reproducible amount of force on the bullet that is governed by the ratchet stop thimble and get an actual number for binning the bullets.

This is very important as the force applied can signficantly influence the accuracy of the read when measuring 1-2 ten thousands of an inch and also if done incorrectly can damage and distort the bullet you are trying to measure – something to avoid since that is the last thing you want in this instance.