Precision Reloading #2: Ogive Comparators tools

[@CHIBA280CRV]

Looks like bob green tool will be in my equipment list.. thanks 👍👍👍

[@patdennis3751]

When you think about it it doesn't matter whether the nut measures exactly from the exact point on the bullet where it contacts the lands as long as it measures the same point on the bullet each time.. I mean how many every day shooters know the exact inside bore dimension of the lands on their rifles? We don't really need to to make great ammo. Here's what I'm getting at. Load a round with a bullet touching the lands and measure it using the Sinclair nut. Note the measurement. Either add the desired jam or subtract the desired amount off the lands. The first measurement is merely the reference point that you either make it longer or shorter from. Whether that first # is the EXACT # or not doesn't matter as long as you are using the same tool with the same hole dimensions every time. As long as the nut references the same point on the bullet each time that is all you need to create accurate rounds @ .010" or whatever jump you want. As long as you are using the same tool each and every time and it measures from the same datum point on the bullet each time, ie the hole never changes, it matters not whether the reference point you start from is the exact OD as the ID of the bore. What you end up with is rounds that are exactly the desired jump or jam you're looking for. I hope I made sense with this long incomprehensible rant.

[@fandango_buttlicks]

I use the hornady bushing comparator and the hornady overall case gauge. I figure out when the longest point is with the COL gauge where its start to touch the rifling and go from there. Now if you change bullets you have to start over because the comparator isnt gonna always measure every bullet the same way so clean the bore really good and start over. For me once i find a bullet that shoots lights out i dont change anyways

[@lewishutchings9344]

I don't shoot competition but I want every little bit of help I can get for a accurate round that I have more time then money in each round. But I do understand what you are saying.

[@edwardlance2379]

This is true. A comparator is only a reference tool. But, to be useful, you do need to use an OAL gauge to find the length of the cartridge where the bullet touches the lands and that is your reference point. Measure that with your comparator, then subtract whatever standoff you want and use the same tool to measure your seated rounds. The actual overall measurement that the tool produces is irrelevant. What matters is the difference between it and what you determine your seating depth to be.

[@Dragon-Slay3r]

Pat double this is the front of the pat double

[@deeeeeeps]

There is one situation it would matter. If you are switching bullets with different angles your length from lands would change. (not that you shouldn't test it anyway)

[@jaybigboy34]

Man your videos are great. You need to make a bunch more. I love watching them all and learning how to precision load from start to finish.

[@ronniehallmark1278]

Both tools serve same purpose. Nothing wrong with either. U will get different measurements from each tool but as long as you use same one your good. Any of these ogive measurement tools just bypass having to measure from bullet tip which varies. Either one of these work fine and will serve u well.

[@SpinandThrowDiscGolf]

Every video starts with "now yes these are expensive" hahahaha

[@kcstott]

I have and use the Sinclair nut. I also make my own reference gauges from the barrel stub using the chamber reamer that was used for the barrel. That is the only way you are going to get a "as close to perfect duplication" of your chamber freebore and throat. but in reality it doesn't matter. all you need is a device that will give you a consistent repeatable result. I have two of the nuts and they are .003" different on the 6mm hole in depth. so one is marked with red dykem to know that this is the one i use for seating depth. Yes I know this video is five years old and you probable have since realized the situation here.

[@gammet2]

Hi Eric I love your videos its very very helpfull to me. Just one question you mentioned that you will make a ojive comparator on your lath can you post that vid here on youtube

[@Dragon-Slay3r]

Nice thanks guys

[@TXPhred1]

Erik, hello, thanks for your videos, my question is, would my bullet seater also need to contact the bullet at the same point as the sorting tool for consistent bullet seating depth? If my bullet seating stem contacts the bullet away from the ogive and that “curve” is inconsistent “after sorting my bullets”, then my seating depth is still off due to this alternate seating stem contact point. Following the logic of greater seating depth = greater pressure then higher velocity, or is the resulting difference in seating depth not relative enough to worry about? The point here is to be the most consistent, yes? Thanks again for your videos.

[@happyhome41]

How does one order the "Bob Green" caliper tools, were one so inclined ?

[@twoalpha]

Erik, I think the Hex tool might be getting a bum rap here. How about a follow up video where you compare twenty same batch bullets, other than .30 cal., on both tools and then give us your observations? Just subscribed by the way.

[@MrT13]

Funny how much stuff has changed in 6 years. Don’t use any of these lol. Actually never did. Did the tape on cleaning rod and razor marks forever. Till I started making loose neck cases by just moving a bullet around with a pair of pliers then put new bullet in and chamber and close bolt. Gently take it all apart and measure.

[@kaseyfisch1535]

The Sinclair hex nut holes are not just drilled straight through. The hole is made with a chamber throating reamer. The hole has about a 2 degree taper, so the diameter of the hole at the outside of the tool is larger than the diameter of the hole on the inside of the tool.

[@ErikCortina]

Kasey Fisch I will check them, but even so, they would contact different bullet profiles at different places on the ogive, which is not correct either.

[@kcstott]

@@ErikCortina the nut is reamed with the most common throat angle for the barrels used in those calibers typically 1.5-2 degrees. it's designed to simulated the ogive contacting the lead angle not the bore diameter.

[@RandallMoore1955]

Thanks for sharing your info, Good to know.

[@danieldunham9978]

When you say bore size are you talking about lands or grooves?

[@godofm3tal1]

I see the point, but at the same time it doesn't really matter. The tool is the measurement medium. As long as you're using the same tool over and over and don't expect to swap tools or share info with another reloader then it doesn't really matter where it's grabbing the bullet. And at $50 per caliber.. that's a lot of scratch to get the same value. Though id suggest the hornady variant over that nut.

[@wanos1752]

I get your point Erik, but I'm confused: you pick up the 7mm BG comparator (you just looked at and put the 30 cal down on the table 10 secs before you picked up this one), and measure it to be .298" ? (so must have been the 30), then compare against sinclair 7mm (you measure it to be .272") saying its 6 thou under. Did you mistake .298 - .272 = 6 thou ? Didn't think the sun was that strong in TX in January, pls correct me if I'm wrong.

[@ErikCortina]

+wano s Yeah, I picked up the 30 caliber one. Thanks for pointing it out, I didn't realize that.

[@Dragon-Slay3r]

@@ErikCortina that's a own goal Tina if you want to win 🤣

[@paulhamilton5634]

You first started off by saying you were measuring the 7mm when actually you measured the 30.

[@georgefisher3370]

Since when is .256 6.5 mm? What are you measuring? My 6.5 (.260 Remington) is .264. Please enlighten me.

[@ErikCortina]

The bore is .256 on a 6.5mm

[@callumhepworth-smith6376]

Am i missing something here, you measured the 7mm but it equalled the 30 cal bore size, and then measured the nut 7mm (which was smaller than the bore by 4 thou). which makes the Bob's one oversized for 7mm by 34 thou. Another point is, dont we just want to measure from the same point on bullet regardless of where it is? as long as it is the same point them we have no (or very little) error. Basically they all do the same job....no? Erik, i am no dissing you at all but this has me a little confused.... and am only half way through. :-) Ah.... in your first time measuring you measured the 30 cal but said it was the 7mm.....

[@Dragon-Slay3r]

Cigar man just followed me there?

[@shopdog310]

These are not "absolute" measurements, they are comparitive,hence the name. The nut is just an old,expedient,easy to make on a drill press tool from years ago. The reason they don't work as well as a "sleeve" isn't hole diameter,it's the rocking motion when you try to use them. But they're easy to make and should teach you to be dang careful holding them for repeatability.

[@manesman3890]

Lastima no entender bien el ingles, aunque las imágenes son descriptivas no capto todo el detalle de tus explicaciones. De todas formas un fuerte saludo desde España y animo con el canal!!!.

[@ronjohnson8386]

ARE THE HORNDY COMPARATORS RIGHT WITH THE BARREL

[@ErikCortina]

Ron Johnson I have not checked them because I don't use them. If you have them, check them and let us know. Thanks.

[@dennislozano4973]

It's a comparator... for comparison. Exactly matching the bore of a particular rifle, or any other dimension for that matter, is not the function of a comparator.

[@jamesakagi8119]

Eric. Where did you buy the tool? I looked everywhere online and cannot find where to buy it. plz link me.

[@joesquid6988]

This! .. I have not been able (yet) to source them either.

[@Dragon-Slay3r]

Lol spent all his money?

[@mortenbreiland3984]

It does not matter as long as you use the same tool every time. That these are caliber specified is not necessary. You need a small one. Where you measure on ogive means nothing as long as you use the same shock all the time.

[@Dragon-Slay3r]

This the pistol cartridge? You looking for bullets? Lol

[@davewilliams2350]

Erik, Great video but your logic is flawed. Bullets do not intersect the bore diameter of a barrel, but rather become tangent to the lead angle of the throat at about the groove diameter. So to accurately compare the base to ogive tangency length of a cartridge and or bullet length you will need a comparator with a conical bore with the same throat angle as your specific chamber. Only then will you be comparing from the same point on the bullet's ogive. Of the two comparators shown in the video, the Sinclair tool will be more realistic to your rifles chamber, if in fact the Green tool has a straight bore. I really enjoy your videos. Keep em coming. Dave Williams

[@dintymoore6657]

The Sinclair hex is cut with a tapered throating reamer, so your one point measurement is inaccurate.

[@georgefisher3370]

.256 bore is a lands measurement, thanks

[@ErikCortina]

George Fisher yes, that’s correct.

[@beachboardfan9544]

How did you find the bob green comparator? If I google comparator the only thing I'm going to find is hornady or whatever brownells/sinclair sell. Guys like you and litz are doing the sport a service, cause even the places you would consider an authority on the subject, spew tons of misinformation AND dont advertise tools and info that arent affiliated to a manufacturer they support.

[@ErikCortina]

Get the Short action customs comparator. They work the same way.

[@apyramidbuilder]

I realized this a few days ago! When I realized I was getting two different readings between my Hornady lock and load device as opposed to the Sinclair comparator. the differences range up to as much as differences up to .005! Essentially the Sinclair measuring tool was a waste of good money. If you're trying to get an exact measurement for a "jump" from the bullet to the Lands and grooves, your measurements will be off!

[@ErikCortina]

+apyramidbuilder Indeed. However, you must realize that the measurement is simply a way to compare from one round to the next, not necessarily an absolute number that can be interchanged between guns. That's why I don't like to post my base to ogive measurement I use on my rifles because it will be different if measured using someone else's equipment.

[@apyramidbuilder]

+Erik Cortina Thanks, that's so true.

[@patdennis3751]

It doesn't matter as long as you use the same tool to measure the loaded rounds with as you used for the initial starting point reference. Both will measure different if two tools measure at different datum points, but remember, the bullet loaded to touch the lands always touches at the same point regardless of where your comparator tool touches the bullet so all you're doing is adding or subtracting length from the bullet touching which will always be the same as measured with the same tool. The two initial touching the lands measurements will never be the same if measured with two different tools, but the rounds length stays the same. As long as you record the measurements to include the tool used to measure with the data is repeatable using that same tool later. Regardless of where the comparator references from on the bullet.

[@Dragon-Slay3r]

I'm in charge of the pyramids Regards The True Sphinx

[@jameshazeltine9346]

The first bfyhb