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Okay so I finally broke down and saw the ways of the wise here on this site and bought a hornady oal gauge and the cases needed for all my guns I load for. Thanks guys for the info. I finally see why I need one. And can't wait for it to arrive. Now, anoit a bullet comparator set from hornady. Do I really need this. It seems to me it's just a little easier to measure with. Or I am sure I'm missing something bso tell me why I need it!?!?!?
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I use these hex guages and feel they are up to the required job. Simple and accurate - dont need much more than that. Check out the vidoe on the linked page on their use.
Last edited by Von Gruff; 03-03-2013, 06:52 PM. -
The bullet comparators let you measure from the ogive of the bullet which can differ from bullet to bullet. If your loading rounds that you want to seat bullets so they are close to the lands, this comes in handy... or atleast it has for me. Instead of a c.o.a.l. it gives you a measurement where the ogive touches the lands for all the different bullets you might use.Comment
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Damnit. Just as I thought I understood. See I thought the coal gague was essentially telling me that. In that it will stop when bullet is touching rifling and as I understand that be the widest point on that bullet from the top. I guess I misunderstood??? Or noComment
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The way to use the COAL guage is to get the COAL for that particular bullet, the individual bullet you use in the Hornady coal guage and seat that particular bullet to that length in a case and then use the hex comparetor to check the ogival length and then that will apply to the rest of that particular type of bullet. If you can see the difference between a tangental and secant ogive ( http://www.accurateshooter.com/balli...ogive-bullets/ ) you can see that you will need to do the two step process for each type of bullet you may want to load. If you set the seating stem length from a coal and then carefully measure the coal of a dozen loaded rounds you will see that there can be a slight difference, but if the seating stem is set to the ogival length then while the coal may vary the ogival length will not. getting into the fine end of accuracy demands but an interesting excercise and leads to some more understanding of the vageries of the bullet manufacturing business and why top BR shooters weigh, measure and inspect the bullets for their shooting games.Last edited by Von Gruff; 03-03-2013, 08:29 PM.Comment
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try to watch this hornady comparator from a guy in youtube
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Ive been using a seating depth tool for several years and have had great results. The measurement to ogive in a comparator has always perplexed me. I understand what youre doing, but fail to understand how you use that measurement in actual seating unless you have a bullet seater plug that fits the projo on the ogive instead of engaging the tip of the projo, or use a micrometer adjustment seater to adjust for every cartridge after measuring with a comparator. Am I missing something here or am I that dense?Originally posted by Von Gruff View PostComment
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Having used the coal guage on one individual bullet and seated for that then the comparetor measurment to the ogive is the measurment I would note on my loading data if I was going to adjust for another bullet so that I could return to load for the first bullet and get it exactly the same as the first batch. The seating stem dosent bear on the actual tip of the bullet but on the start of the ogival curve so the tip length can vary. The 'cup' on the seating stem will not match the ogive on different shape bullets and will bear on different parts of them which is why there is sometimes a ring around the bullet where the cup shape is different to the bullet shape. The seating stem cup sometimes needs a little doctoring to stop tip deformation so the ogival measurment is the most exact.Comment
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I am sitting with a box of 123gn A Max's and the first ten had different oal measurments. 1.236 - 1.237 - 1.236 - 1.241 - 1.239 - 1.238 - 1.237.5 - 1.236 - 1.237 - 1.238, So that is a varience of 1.236 - 1 241 or .005 and that is not unusual.Comment
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roger that gruff. thanks for the infoComment
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Soooo in other words. For hunting not so much? For comp and longer ranges its a have to do kinda thing?Comment
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For accuracy in the load room and on the range - Yes. For hunting under 300 yds no but when it stretches out a bit then there as well.Comment
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The real benefit in using a base to ogive measurement to control bullet seating depth is to deal with lot to lot variations of bullets. Match shooters carefully fine tune their long range loads, first using a ladder test to find a node, then vary primers and seating depth to fine tune for optimum accuracy. Then what happens when you get a new lot of bullets? If you have recorded only COL you will have no way to insure the jump from the seated position to first contact with the lands is optimum. If on the other hand you measured the base to ogive you can adjust COL to keep the jump constant. You can also adjust for throat wear with more certainty.
Some bullets, like the 120 SMK and 123 AMX are very forgiving of jump and this is of little importance. VLD bullets are much more finicky about jump and this may be a significant factor.
I know Bill designed the Grendel throat with a compound angle to mitigate this finicky attribute of VLD bullets. But in my experience the compound throat angle is soon gone anyway due to throat erosion. So I fall back to controlling seating depth by base to ogive rather than COL.
BobComment
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i really love this site. mostly because knowledgeable and generous gurus like Bob, LRRP, Bill A, and several others make this site a fountain of genuine and quality help. much of what i thought i did know, i did not.
this community owes heartfelt appreciation to you guys.Comment
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Thanks. Makes sense. I have a new rest coming Wednesday and a hundred rounds of various loads made. For this Saturday. I can hardly waitComment
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