Has anyone made one of those bullet comparators that looks like a hexnut with holes drilled in the flats? I think it's a good idea and was considering making one. Any tips you can share?

"bullet comparators that looks like a hexnut with holes drilled in the flats"

Works for me. But, most common large nuts are too rough to be consistantly measured, you need a nut with machined flats. AND a reamer to get the bullet (ogive at bore diameter) right.

Yes. Sinclair sells the Hex ones and their brag, IIRC, is that they are reamed with an actual chamber reamer to get the ogive touch-down point to match an actual throat taper.

Personally, I find the convenience of the caliper adapters too good to resist. Any sort of rocking or other alignment awkwardness from juggling a loose third element int the setup makes measuring slow. The Hornady comparators (bought out from Stoney Point) have an offset for use with their overall length gauge, making them good but not quite as easy to use as the centered Sinclair adapter (http://www.sinclairintl.com/product/5575/Bullet-Comparators). The latter uses stainless inserts (http://www.sinclairintl.com/product/11173/Bullet-Comparators) with tapered holes to mimic throat angles rather than the aluminum ones the Hornady has. (If you have a lathe and a chamber reamer, you can make your own insert as I did for 6.5 mm.) If you couple the Sinclair tool with the Davidson case bases (http://www.sinclairintl.com/product/11246/Bullet-Comparators), you have an alignment error free tool, making measuring really quick.

As I've posted before, I use nothing but my calipers. I lock the jaws at bore diameter (NOT rifling diameter!) such as .300" for 30-caliber, .220 for .22-caliber, etc. Lightly turn a bullet in the jaws and you will have a scribed line on the ogive at the point where the bullet will first touch the lands. Like this:

http://i27.photobucket.com/albums/c170/RockyRaab/offland.jpg

Now, measure from that line to the base of the cartridge. Record that number and you can set the bullet seating depth accurately from then on - with ANY bullet. Like this:

http://i27.photobucket.com/albums/c170/RockyRaab/Junk0308005.jpg

Rocky,

You're not taking laziness into account.

Nick, if I were handier with machine tools - or HAD any - I might have just done things the hard way.

But why? LOL!

I have made a few things like the Sinclair "nut" comparator and it is not difficult at all. However, unless you already have the tools (I did), it will be cheaper to just buy the off-the-shelf product.

One point in favor of the Sinclair tool - you may be able to use one of the 'bigger' holes in it to slip over the case neck and rest against the case shoulder (with no bullet in the case). Measuring this, before and after resizing, will tell you how much the shoulder of a bottleneck case has been set back during the sizing process. Just as an example, the .30 or 7mm hole in the Sinclair tool could be used to test how much the shoulder of a .22-250 was set back during resizing.

A simple tool like that can be made just with ordinary twist drills and an ordinary hex nut, as the hole just has to fall somewhere between the maximum neck diameter and nominal shoulder diameter.

MikeG - That's what I was thinking when I saw the tool. It would be a good way to measure cases. I do a fair amount of reforming, 223 to 221 Fireball. My gun has a tight chamber and it is a little tricky to get the shoulder pushed back far enough with my form and trim die. What you described would allow me to check the case fit/size without feeding it through the gun.

Should take you about 5 minutes in the shop, then ;)

. . . That's what I was thinking when I saw the tool. It would be a good way to measure cases. I do a fair amount of reforming, 223 to 221 Fireball. . .

If your not looking to find bullet ogives or even an exact SAAMI shoulder headspace datum, but just a consistent point of comparison for the Fireball cases, you can skip the whole holed hex nut shape business. Just pop down to Lowe's and poke through the odd hardware drawers until you find a tubular metal spacer with a 5/16" ID hole through it. Its ends will be square enough for the calipers to register the same number every time. If you want to get fancy, you could wax the caliper jaw at one end and use some JB Weld as bedding compound to give the spacer a snug enough fit to free one hand up during the measurement.

In my opinion if you are going to take the time and have the interest to make accurate consistant handloads you have to buy the correct tools. if you have the machined tools then and only then will you be consistent and have true confidence in your finished product...
Tikkamike