Just A Friendly Reminder...

[yukonal]

Check the base to ogive measurement on the individual bullets...every time you open a new box of bullets.

Same lot rarely if ever changes, but seems like ALMOST every time I've switched lots over the years, the new ones are a little different. Up to .005". That's not much, for the most part. But, .005" difference can be HUGE when you are messing around right at the lands.

This has been discussed before, but bears repeating. Opened up a new lot today, in the middle of a 100 round batch of reloads, and had .004-.005 difference from previous box. Just changed my seater depth, and kept on boogieing. (is that really a word?)

Happy New Year guys, and best of luck shooting in 2018!

 

[MSS]

Good advice!

 

[LHSmith]

Good advice ONLY if you have the proper equipment and skill to obtain consistent measurements....consistent means you read the exact same measurements from the same bullet after three readings. Otherwise a huge waste of time- BTDT.

 

[fyrewall]

I am about to plunge into the world of ogive measurements. I have many bullets of the same kind (400-500 of same) but of different lots. Like .204 40 Vmax, .243 87 VMax, .243 105 Amax, 6.5 100 Amax, 6.5 120 & 123 Amax, 6.5 140 Barnes Match Burners, several boxes of ELDX & ELDM & 400 .224 70 Berger VLD's saved for special occasions. My plans are to sample 20 bullets of each lot using a PTG 6 sided gauge and my caliper, measuring ogives. I have made a simple Excel routine to determine averages, X spreads, standard deviation (SD) and low and high averages. Logically, and as pointed out by another member, this would not show very much as bullets of the same lot would probably not vary more than .003 (X spread) making the statistical stuff witless as the SD is real tiny - like mostly the same ogives. But, measurements of different lots might be of worth and be used to sort.

Upon reviewing the Berger info regarding their VLD bullets their recommendation is to use COAL to adjust seating depth some distance back ("jump") - apparently Berger has enough confidence in their ogive datum stuff to suggest COAL (tip to brass base) be used to adjust seating depths (great but sort of expensive bullets). My experience has been that my older rifles that show much visible wear often to the extent of having uneven land wear seem to do better with bullets just contacting the lands. My new rifles like to be seated some .01 back for both Berger & Hornady bullets (secant ogives). It does not seem to matter much with the 6.5 Barnes Match burners. I have no intention to measure all bullets but will use my 20 bullet sample by lots to load ammo for each rifle.

I can understand the word "boogieing" - dance? and might even use it to describe bullet dispersion on distant targets.

 

[yukonal]

By all means, measure your Bergers at the ogive. They are one of the brands I was referring to when I said there is differences between lots. At least there has been for me in the past. And I shoot thousands of them every year.

 

[rogn]

Hornady caliper too works on some, and you can make your own gage inserts out of 1/2" aluminum rod with a drill press and the closest drill bit to bore size. A lathe of course makes this a snap.

 

[JRS]

Shoot BIB Bullets, and you can forget about measuring

 

[dcali]

Measure the Bergers (like all the other majors). You don't need to break out the calculator and stats book - it will be obvious. Within a lot is usually +/- .001 or less. Lot to lot can be 10x that. I haven't found it to be a big deal, but it's good to know what you're shooting in case the new lot doesn't work out.

 

[fyrewall]

After I am done with this each bullet box will be labeled with a felt tip pen to ID ogive position, as an average, probably like a 3 digit number, on the basis of a 20 bullet sample. The last 4 of the lot number will be displayed because existing lot numbers on boxes are tiny. Data for each lot will be stored on Excel spread sheets combined with performance notes. No paper records or calculators. No measurements and sorting for every bullet in the box, only 20 for each lot. Same process for all bullets. I have a large variety of bullets of different lots and ages.

Some lots might shoot better in some guns than others. Some lots may have varying degrees of uniformity.

I trust and expect that variations within lots will be tiny and of no importance for my casual shooting. The same approach is planned for velocity spreads. There are 1000's of different combinations of components to produce ammo for my use and I need to simplify, economize, and control my 20 gun ammo production.

 

[PatMiles]

Good advice sir.

 

[Metal God]

If your seating stem seats the bullet pretty much from the ogive or even half way between the ogive and tip . Why would it matter how far the base is away ? Shouldn't you be measure where your seating stem contacts the bullet in relation to where the ogive is . If there's a difference between those two measurements from lot to lot is where your adjustments should come from , yes/no ? It would seem to me anything past the ogive has no relevance to where the bullet will be as it relates to the lands , you're not pulling the bullet into the case from the base . Put another way . If your seating stem contacts the bullet at the .305 diameter mark of a 308 bullet . You then use two different weight bullets 1) 155gr the other 2) 200gr . They are both going to be seated pretty much the same distance from the lands . How ever the 200gr bullets base is going to be way further away from the ogive then the 155gr bullet . What does the base have to do with this , Am I wrong there ?

 

[Bigguy1951]

I was shooting 140 Berger VLD hunting bullets and ran out. The new batch is .010 different (less) in base to ogive. Check your bullets. Oh, these are 0.264 bullets.

 

[dkhunt14]

If your seating stem seats the bullet pretty much from the ogive or even half way between the ogive and tip . Why would it matter how far the base is away ? Shouldn't you be measure where your seating stem contacts the bullet in relation to where the ogive is . If there's a difference between those two measurements from lot to lot is where your adjustments should come from , yes/no ? It would seem to me anything past the ogive has no relevance to where the bullet will be as it relates to the lands , you're not pulling the bullet into the case from the base . Put another way . If your seating stem contacts the bullet at the .305 diameter mark of a 308 bullet . You then use two different weight bullets 1) 155gr the other 2) 200gr . They are both going to be seated pretty much the same distance from the lands . How ever the 200gr bullets base is going to be way further away from the ogive then the 155gr bullet . What does the base have to do with this , Am I wrong there ?

Because if the bearing surface is longer it makes more tension in the case and more friction in the barrel. Seen as much as .050 or more in a box. When trying to win a match at 1000, this can be enough to make you lose. In our game you might lose by .005 in a 10 shot match. Does one or two .001 hurt, probably not but I am tryimg to get the bad ones out. Since I am measuring them, why not just batch them the same. Matt

 

[Metal God]

dkhunt : I thought he was talking only in relation to the lands . If he is talking bearing surface then I can see that being an issue . 50 thou would seem to be a lot of a difference .

My suggestion then would be to also check the boat tail to make sure some of that difference is not there . Then I make sure the ogive measurement was as close to the actual ogive as possible . I have the Hornady comparator and found there inserts to sit way forward of the actual ogive where the bullet construction may not be as consistent . I switched to the Sinclair SS inserts that are much better for this purpose . I'm sure there are ever higher end ones to use but those seem to be the most commonly used .

 

[grovey]

Assuming the difference is enough to open your load up ,is there a general rule of thumb for tweaking it? Be it seated shorter or longer, for example... If you're now seating 0.10 further in the case with your new batch, you would be using up some of the case volume. Actual case volume, caliber, fb, or bt bullets, and bearing surface would all be variables as to how much , Correct?

That should raise pressure, but because it depends on where the bullet is seated in relationship to the lands that's a variable too. Would a change in the powder charge be the way to address it, or could the difference in the bullet shape mean a change in seating depth change is in order?

 

[jimmymac]

I switched to the Sinclair SS inserts that are much better for this purpose.

Do the Sinclair inserts fit the Hornady body? Thanks.

 

[grovey]

Assuming the difference is enough to open your load up ,is there a general rule of thumb for tweaking it? Be it seated shorter or longer, for example... If you're now seating 0.10 further in the case with your new batch, you would be using up some of the case volume. Actual case volume, caliber, fb, or bt bullets, and bearing surface would all be variables as to how much , Correct?

That should raise pressure, but because it depends on where the bullet is seated in relationship to the lands that's a variable too. Would a change in the powder charge be the way to address it, or could the difference in the bullet shape mean a change in seating depth change is in order?

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