Taking a Punt
I am topping up Comparator inserts for my SInclair body, I have some of the old ones that just have a straight hole in them. They work just fine as long as you are really square with the caliper jaw. I am hoping that I will not run into the "too much taper" problem that others have mentioned but that can possibly be fixed by removing material from the face of the comparator body and allowing the body to engage the ogive before contacting the case mouth... We will see!
OK fit with a little wobble
I mostly hunt but I like a 1 hole group at 100 yards with 5 shots. These comparators are good but have a little wobble. Construction will outlast me.
No wobble
Has no wobble but comes close to bottoming our on the case with 200 grain Nosler ballistic tip. The hole could have been a few thousands smaller. Other than that, superior construction and nice weight.
Not a precision gauge
Ordered 3 inserts and they all had significant dings at the entry to the gauge hole, that require dressing out before they can be used. Steel appears to have been heat treated, but suspect that was done after the damage occurred.
Well built, but not accurate
I have the Hornady bullet comparator that I normally use. When my shooting partner and I noticed a .010 difference in our Hornady headspace comparator, I ordered the Sinclair bump gauge and the bullet comparator. The Sinclair tool is produced from quality steel and is well constructed. My issue with the tool is that on Sierra MK and Berger Juggernauts, it slides all the way down almost to the base of the bullet. I can't get repeatable results with this tool, where I can with the Hornady tool which is only made of light aluminum. The Sinclair tool does not seem to be measuring from the ogive, but more from the bullet base. As another user reviewed, when used with Comparator body, it measure 1.1 inches, rather than 1.0 like the Hornady. Because of the inaccuracy and non-repeatable readings on the same bullet, I can't continue using this.
Perhaps Too Much Taper
I was using this insert to sort 69 grain Sierra Match King bullets. The ogive on the bullet combined with the taper on the insert makes it hard to get repeatable measurements using a caliper. It's much too easy to cause the bullet to move further down into the insert while taking the measurement. The same thing happens with assembled rounds. For these bullets, the Hornady insert works better. I have a bullet sorting stand and comparators on order, I hope that is more repeatable. Also, I use a dial caliper. I can zero out the thousandth's but not the tenths of an inch. It would be nice if the comparator assembled to the insert would measure about 1.01 inches rather than 1.11 inches. It's easier to mentally subtract 1 inch from the measurement than 1.1 inches. If you use a digital caliper, it's not a problem.
Improved design, except for 1 problem.
All the details in my rating for the 6mm comparator apply here too, but I've found a problem with the .204. To get optimum groups with my Cooper M21 20 TAC, some of my loads need to be seated very deep. The Sierra 32 gr MK and Hornady 45 gr SP achieve 0.25 MOA or better, when seated 0.100" off the lands. That's right, 1/10" jump! At this depth, this new comparator runs into the mouth of the case before it can come into contact with the bullet, so it's useless. And I'm not seating these bullets past their bearing surfaces. I'd like to see the geometry of this insert changed so that the max diameter of it's tapered hole would be 0.202". Right now I measure it at 0.211". In fact all of these new Sinclair inserts should limit their maximum taper diameters to (at most) the diameter of the bearing surface of bullet they are used for.
Does not work for 6.5CM
Just received the 6.5mm comparator insert. Looks well made and hefty compared to the Hornady version. However the bullet seats too deep and the ogive depth changes by several thousands depending on slight changes in caliper pressure. Very disappointed. Will continue using the Hornady.
My Mistake
Purchased these in 6.5mm, 7mm & .308 size. Taper is so great that while you can take a measurement of some arbitrary point it has no value. Had hoped to use to determine bearing surface of bullets. The Hornady inserts have less but still too much taper for my intended purchase purpose. Perhaps with a lathe can cut away useless taper. At present these are of no value to me.
Sinclair International Bullet Comparator
I just plain don't like them. For me they fall extremely low on the bullet ogive. If you are not very careful the bullet will stick in the comparator when measuring your length.
