What to do about COAL inconsistency?

[MontanaRifleman]

This is something that I have not paid much attention to in the past so looking for your experiences and opinions.

In seating 105 hybrid's in a 6-284 and 160 Matrix in a 6.5 WSM, I am finding up to .020 difference in COAL's. In checking the bullet OAL's I am finding up to .015 total variation. I am thinking this will lead to about that much variation in jump to the lands which seems significant to me.

Now I know some of you sort your bullets by bearing surface length which is something I have not tried yet. Still, that will probably not completely solve the COAL variation.

Let's hear what you think so all of us can learn something maybe.

 

[Shooter264]

Measure off the ogive. That's the only thing that counts. It is the first thing that touches the lands. If you get a comparator and seat your bullets off the ogive as opposed to COAL you will find your inconsistencies usually less than .002". They only time I would look at COAL is if I was marginal on loaded rounds fitting the mag box. Hope I understood your question correctly.

 

[Mark611]

their lots of ways to do it but how I do it is I use a tool like this to measure the ojive measurement of the bullet http://www.sinclairintl.com/reloadi.../sinclair-bullet-sorting-stand-prod38769.aspx to keep the bullets all consistent sorting them by the ojive length and I use a competition seating die and a consistent ram stroke on the press that's has the same feel every time and if you do this you can keep your ojive measurement to .005 on an inch or perfect from round to round

 

[jimbires]

if your ogive to base is varying that much , be sure the bullet tip is not bottoming out in the seater stem . the seater stem should push on the ogive .

 

[Mark611]

the best thing to do is use a seating die that doesn't come in contact with the tip of the bullet, gun)

 

[sp6x6]

Mark have noticed same thing as I reload and does not make sense as bullet is seated off same place with seating stem. But I have found variance not as much but still. So if I am having issue I use micro seater and seat slight long, for me usually .005 enough. Run them then fine tune seater to get the rest the same my have to adjust once more. I check them with comp. then fine tune. It has something to do with comparator and seat stem dont use same ogive line

 

[CA48]

Sounds like your measuring off the metplat. Like others have said measure off the ogive. I too started paying more attention to this issue a few months ago. I was getting about .005 variation between COAL measuring off the ogive and much more off the tip. The biggest thing to practice is having consistent pressure at the end of the ram stroke but I was still around .002-.003 variation. I've had some rounds loaded to do a test for awhile now but still need to do it. I loaded 10 rounds to .000 variation, all exactly the same. This takes some time and your not going to accomplish this everytime you try. Then I have some rounds loaded to .002 variation in COAL. And then my last group of rounds is around .005 I think, il have to go back and look it's been a while since I loaded them. I loaded 10 of each and plan to shoot them through the magneto speed while checking the groups at proly around 400-500 yards havnt really decided on distance yet but I want it to be far enough to see how the different variations will effect long range groups but not far enough for the wind to have a large effect on my results. 10 rounds for each group 30 rds total, isn't really enough to prove anything group wise but it's a start. Going to interesting how much of an effect it has on E.S. though. If your press and die combo allow it set it up to when you seat your bullet your shell holder bottoms out on the bottom of your seating die, saw Broz post that I think, been wanting to try it but my combo doesn't allow it. I'm going to be testing this with my 338 EDGE AI and 300 berger OTMs. Also as mentioned previously my first problem was my seater stem was designed around the 300 SMK and was bottoming out until I switched to the VLD style.

 

[MontanaRifleman]

Measure off the ogive. That's the only thing that counts. It is the first thing that touches the lands. If you get a comparator and seat your bullets off the ogive as opposed to COAL you will find your inconsistencies usually less than .002". They only time I would look at COAL is if I was marginal on loaded rounds fitting the mag box. Hope I understood your question correctly.

So how do you measure off the ogive? If I could, then I could adjust the micrometer seater to accurately seat each bullet from the lands.

their lots of ways to do it but how I do it is I use a tool like this to measure the ojive measurement of the bullet SINCLAIR BULLET SORTING STAND | Sinclair Intl to keep the bullets all consistent sorting them by the ojive length and I use a competition seating die and a consistent ram stroke on the press that's has the same feel every time and if you do this you can keep your ojive measurement to .005 on an inch or perfect from round to round

My strokes are complete and consistant. I sometimes spin the round and run it up into the seater a second time and get the same result.

So, I'm not quite sure how you know what your bullets jump to the lands is using this tool?

 

[MontanaRifleman]

if your ogive to base is varying that much , be sure the bullet tip is not bottoming out in the seater stem . the seater stem should push on the ogive .

the best thing to do is use a seating die that doesn't come in contact with the tip of the bullet, gun)

I am using Hornady seaters with the micrometer seating stem and AMax bullet seater stem. The meplat doesn't come in contact with the seater. The seater stem comes in contact with the ogive about halfway between the tip and the bearing surface.

 

[MontanaRifleman]

Mark have noticed same thing as I reload and does not make sense as bullet is seated off same place with seating stem. But I have found variance not as much but still. So if I am having issue I use micro seater and seat slight long, for me usually .005 enough. Run them then fine tune seater to get the rest the same my have to adjust once more. I check them with comp. then fine tune. It has something to do with comparator and seat stem dont use same ogive line

So how do you use a comparator to check and adjust a seated bullet?

Sounds like your measuring off the metplat. Like others have said measure off the ogive. I too started paying more attention to this issue a few months ago. I was getting about .005 variation between COAL measuring off the ogive and much more off the tip. The biggest thing to practice is having consistent pressure at the end of the ram stroke but I was still around .002-.003 variation. I've had some rounds loaded to do a test for awhile now but still need to do it. I loaded 10 rounds to .000 variation, all exactly the same. This takes some time and your not going to accomplish this everytime you try. Then I have some rounds loaded to .002 variation in COAL. And then my last group of rounds is around .005 I think, il have to go back and look it's been a while since I loaded them. I loaded 10 of each and plan to shoot them through the magneto speed while checking the groups at proly around 400-500 yards havnt really decided on distance yet but I want it to be far enough to see how the different variations will effect long range groups but not far enough for the wind to have a large effect on my results. 10 rounds for each group 30 rds total, isn't really enough to prove anything group wise but it's a start. Going to interesting how much of an effect it has on E.S. though. If your press and die combo allow it set it up to when you seat your bullet your shell holder bottoms out on the bottom of your seating die, saw Broz post that I think, been wanting to try it but my combo doesn't allow it. I'm going to be testing this with my 338 EDGE AI and 300 berger OTMs. Also as mentioned previously my first problem was my seater stem was designed around the 300 SMK and was bottoming out until I switched to the VLD style.

My seating stroke is good. I have run some rounds several times up into the seater and always get the same COAL. I am sure the problem is variation in the bullet ogive and bullet OAL.

I,m not really concerned about the COAL. Just want to make sure I am getting a consistent jump which I don't think is possible with this much variation in COAL and bullet OAL

 

[Wachsmann]

So I had the same issue running the 210 VLD's. I made the poor mans VLD seater which I took a small drill bit and drilled out the seater stem slightly and then repolished the inside. I just seated 18 bullets last night for a ladder test all measuring off the ogive using my hornady comparsion gauge and mic. All bullets were spot on for each group of 3. Before drilling out the die I used to get as much as .012 to .10 COL difference in my bullets. The far extreme would be around .015. So if I measure from the ogive for a given seating length the bullets come out the same now. I don't expect great changes but I hope it will tighten the groups up a little and also bring down the velocity spread for the same powder charge. It would be nice to see some single digit velocity spreads. I usually get about 14fps in my spread. Hope this helps.

 

[Capt. D]

I bought Shawn Carlocks, Reloading for Long Range video and have nothing but good things to say about it. My very first set of loads were all a consistant .020 off of the lands measured from the ogive using a Davidsons comparator. I full length resize using a Redding Type S die set. I have followed his techniques to the Tee to this point and have not been disappointed. At some point as my experience grows I may make some adjustments but at this point I use the old addage If it aint broke don't fix it. Hope this helps.

 

[CA48]

So how do you measure off the ogive? If I could, then I could adjust the micrometer seater to accurately seat each bullet from the lands.



My strokes are complete and consistant. I sometimes spin the round and run it up into the seater a second time and get the same result.

So, I'm not quite sure how you know what your bullets jump to the lands is using this tool?

To accurately measure off the ogive get a comparator, hornady makes an inexpensive comparator that will attach to your calipers and it has caliber specific inserts.

Take a loaded round seated to lands measure it with your comparator (for the hornady model I mentioned) then say your jump is .015. Seat the bullet .015 deeper measuring off the ogive with your comp. as you go. When you reach your desired jump measure your COAL with the comparator. Then you have your New COAL measured off the ogive, which will be consistent from bullet to bullet, unlike measuring bullet oal from the meplat. Hope that was clear.

 

[Mark611]

another thing you my want to look at is as we use these tools things tend to loosen up so you might want to check to see if everything is still tight and liner as it should be