Just when you think you know what your doing.

[matt_brown]

The other night I was loading some 243 and I ran out of bullets. I only needed 6 more to finish my batch so I opened up another box(same weight, manufacturer, style..... not the same lot number). When I measured the last 6 bullets they were 0.017" longer than the others. I sat there and scratched my head wondering what I had done differently. I used my hornady C.O.L gauge with one of these new bullets and it measured 0.017" longer than the ones I used before. This triggered my OCD so using my bullet comparator I measured the other 94 in the box and came up with 4 different lengths. I had no idea that the ogive of the bullets from different lot numbers were different.

Tonight I took a brand new box of 6.5mm bullets and measured length (using comparator) and weight. All 100 bullets were within .1gr but the length varied from .664 to .670. I sorted everything into groups (as pictured) so I can try them on the range.

Makes me wonder how many times I have jammed bullets into the lands on accident. I usually load my bullets .003 off the lands. If I would have used one of the .670 bullets in my C.O.L gauge and then backed it off .003 then my .664 bullets would have been .009 off the lands or vise versa . So this is my excuse for that 1 or 2 flyers that I always end up with.

I know some of you are shaking your head at me right now. hopefully I have helped some of you out.

This is a pic of the bullets that I had sorted out

 

[treefarmer]

Re: Just when you think you know what your doing.

Is the bullet length different? If so, wouldn't the longer bullets be seated deeper but the cartridge oal lengths stay the same?

 

[7mm08]

Re: Just when you think you know what your doing.

And those are "quality" bullets as well.

 

[MUP]

Re: Just when you think you know what your doing.

Wow! .300" !? That's almost half another bullet length! :shock:

 

[Hunter 257W]

Re: Just when you think you know what your doing.

Surely you didn' mean they varied .30? As MUP said, that would be half a bullet length variation and I can't believe any bullet manufacturer would let that out the door of their factory?

With the 6.5mm Bergers I agree with Treefarmer. The longer bullets would be seated deeper since the seating die more-or-less contacts the bullet on it's ogive. Because of this, the distance off the lands should stay more consistent that it seems when only looking at bullet length variation.

 

[matt_brown]

Re: Just when you think you know what your doing.

2.287"
2.302"

same exact bullet but different ogive on bullets which gave different length bullets. I also use competition dies for my .243

 

[matt_brown]

As pointed out above. I am horrible at math. 0.017" difference

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[matt_brown]

Re: Just when you think you know what your doing.

Surely you didn' mean they varied .30? As MUP said, that would be half a bullet length variation and I can't believe any bullet manufacturer would let that out the door of their factory?

With the 6.5mm Bergers I agree with Treefarmer. The longer bullets would be seated deeper since the seating die more-or-less contacts the bullet on it's ogive. Because of this, the distance off the lands should stay more consistent that it seems when only looking at bullet length variation.

I use a bullet comparator to check my bullet length. I never measure from tip to primer

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[GOODWIN]

Re: Just when you think you know what your doing.

Surely you didn' mean they varied .30? As MUP said, that would be half a bullet length variation and I can't believe any bullet manufacturer would let that out the door of their factory?

With the 6.5mm Bergers I agree with Treefarmer. The longer bullets would be seated deeper since the seating die more-or-less contacts the bullet on it's ogive. Because of this, the distance off the lands should stay more consistent that it seems when only looking at bullet length variation.

I use a bullet comparator to check my bullet length. I never measure from tip to primer

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Agree. Your OAL will be different but the length with the comparator should remain consistent as well as your distance to lands. If not then you might want to trouble shoot another problem. Nothing in your seating die is there?

 

[matt_brown]

I'm sure my die is correct. The reason my other 6 bullets were different is becasue the ogive measured different from box to box. I'm guessing it was because the lot numbers were different.

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[TiminTN]

Re: Just when you think you know what your doing.

The lengths are not the only possibility, the diameters can and will vary lot to lot. If the newer ones are fatter, create a little more seating force, will transition into longer OAL.

 

[DaveB]

Re: Just when you think you know what your doing.

Zip something off to Berger. I would expect lot to lot consistency for the distance from base of bullet to ogive.

You may remember a picture of a TNDeer member's bench. In the picture they had the 500 or 1,000 bullet boxes of Berger's and at the time I thought (1) Wow a lot of green there and (2) he wants single-lot numbers for consistency.

 

[matt_brown]

The point that I am trying to get across is that I ASSUMED when I checked my OAL with my gauge using a certain bullet that I could use that length for that bullet regardless of lot number. What I learned was that the ogive varies not only from lot numbers but from almost each individual bullet. I may be wrong but I feel like breaking my bullets down into groups that are the exact same length and seating them the same will help with accuracy

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[Hunter 257W]

Re: Just when you think you know what your doing.

I thought you must have been writing a different number than what you meant. Also I took you literally that you were measuring just a bullet not a loaded cartridge. It is surprising to see that much difference in overall cartridge length using the same seater die setting. I've personally never owned or used a comparator so don't know if this is normal or not??? I would have thought that since the seater plug is typically contacting the bullet somewhere on it's ogive - as is the comparator - that you'd get very consistent lengths when measuring using a comparator. I guess the only way to know that is for you to do more measurements with more different batches of bullets to see just how much variation is "normal". No doubt sorting bullets into like groups should improve accuracy. Keeping records as to how much improvement you get (with group size) will let you decided if it's enough to justify the extra work involved with sorting. Keep us posted.

 

[Deer Assassin]

Re: Just when you think you know what your doing.

varying lots varying results

 

[GOODWIN]

Re: Just when you think you know what your doing.

I'll be interested in your accuracy results by sorting them. I've seen quite a bit of difference in length of bullets even in the same box. Never had a comparator to measure length to ogive.

What I was saying, and someone correct me if I'm wrong, is that your length to ogive on the loaded cartridges from the shell base ought to be close to the same. No matter if the bullets vary in total length and/or length to ogive. Due to the fact your seating die is using the ogive to seat the bullet not the bullet tip. This assuming the diameter of the bullets (as someone pointed out) are the same and the pressure when seating. Right? Wrong? My head hurts.

 

[matt_brown]

Re: Just when you think you know what your doing.

I see what your saying.

All my loaded cartridges from box A were the same length no matter the actual bullet length. When I added 6 bullets to finish my batch from box B my oal changed. I assume because the ogive was different in box B. When I used a bullet from Box B in my gauge it had a completely different col

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[DaveB]

Re: Just when you think you know what your doing.

These are Berger Very Low Drag bullets and are monolithic copper bullets no lead and they are LONG. The reputation is each bullet is like the preceeding like the following etc. You pay for this quality. I would expect every bullet in a given run to be within MINUS .003 in overall length. From base to ogive should be the same every time, the variation would be in the drawing out of the tip.

I have given up measuring bullets because my accuracy needs don't extend that far. From base to ogive I found (308 only) rare exceptions to length.

Keeping the jump as small as possible without touching the lands is one component of accuracy.

One thing for sure, this thread shows how a comparator can be of help.

 

[TiminTN]

Re: Just when you think you know what your doing.

1 is ok 2 is better.

 

[waterfowlwidowmaker]

Re: Just when you think you know what your doing.

These are Berger Very Low Drag bullets and are monolithic copper bullets no lead...

incorrect, try again please

 

[mr.big]

Re: Just when you think you know what your doing.

Berger VLDs are lead core copper jacketed bullets,,they are very good bullets but if you want them to measure exactly the same you will have to sort them even in the same lot,,if it is worth it or not will be up to you,,,try and find where it shoots best with over a .015 jump or over a .015 jam and you should not have to sort them,,if you are trying to shoot with a .005 jump or jam and not sorting you could have wild fliers and bad ES,,

 

[treefarmer]

Re: Just when you think you know what your doing.

This happened to me 2 years ago and from your post I just now realize what was happening. I was loading some 30-06 with Hot-Cor and the OAL from bullet tip to primer kept changing. I assumed I was going crazy and kept adjusting the bullet seating die every couple rounds. Now I realize it may have been bullet variation. I wouldn't have expected enough variation to even measure. I bet in the manufacturers process they have many molds they cast at the same time and there is variation from mold to mold. Molds wear over time causing variation.