What gives on the ogive??

chambered221 · Posted: Fri Dec 28, 2012 6:38 pm Post subject: Re: What gives on the ogive??

Seen this happen a number of times with Nosler bullets !!!
Seems as though they often mix lots/batches together before boxing and shipping.
Once had 4 different ogives in one box of .243 55gr. B-Tips.
The surprising thing was it didn't seem to affect accuracy. Shocked

fnuser · Posted: Sat Dec 29, 2012 7:21 pm Post subject: Re: What gives on the ogive??

I don't think Ive ever encountered this, but it does make an interesting read. I think I usually reload in batches of 50 or 100 so I probably just use a box and go to the next. How did your bullets get mixed up?

Dawgdad · Posted: Sat Dec 29, 2012 8:39 pm Post subject: Re: What gives on the ogive??

chambered221 wrote:

Seen this happen a number of times with Nosler bullets !!!
Seems as though they often mix lots/batches together before boxing and shipping.
Once had 4 different ogives in one box of .243 55gr. B-Tips.
The surprising thing was it didn't seem to affect accuracy. Shocked

That really does not surprise me that you would get good accuracy since your bullet seater was striking at the same diameter on the profile of the bullet so jump would be the same for all lots even though the OAL's were all different. The small difference in case volume this few thousandths would not change pressures significantly. So with similar bullet jump and no change in pressure the change in OAL does not affect the key parameters of accuracy.

If you adjusted them to all be the same OAL you might see some different results.

This is not to say you should not strive to make the most consistent bullets possible but the true impact of some of the things we measure is not as big as we think it would be. It still gives you the mental edge of confidence.

Vince · Posted: Sat Dec 29, 2012 9:32 pm Post subject: Re: What gives on the ogive??

Good point DD. I think we tend to get a bit anal about some things...things that will not necessarily have a significant, if any, bearing on the end result. However, if searching for that elusive one hole group is what you do, then fill ya boots and enjoy the experience.

chambered221 · Posted: Sun Dec 30, 2012 7:03 pm Post subject: Re: What gives on the ogive??

Dawg..... I use a RCBS precision mic, it's point of measure is just in front of the bearing surface, (at approx. .236) not the ogive.
Any inconsistencies I get with the ogive and OAL will also show up here, that's how I originally discovered the box with 4 different ogives.
That box of bullets varied by as much as .012 in overall loaded cartridge length but varied only .001 in actual bullet length.
This leads me to believe that the position of the base and bearing surface of the bullet when seated varied .012 as well. Thus changing the amount of jump.

chambered221 · Posted: Sun Dec 30, 2012 7:11 pm Post subject: Re: What gives on the ogive??

Vince wrote:

I think we tend to get a bit anal about some things...

I agree ....... but I like the knowledge and mechanics of it !!! Very Happy

10spotterminator · Posted: Mon Dec 31, 2012 12:39 am Post subject: Re: What gives on the ogive??

YEP !

Just when I get too retentive about this stuff I get a load like the one for my 300 Winny using Barnes 168 gr TSX "MATCH" bullets . The OAL as well as the measure to the ogive are all over the place by as much as .017 but this load shoots inside of 1 inch at 200 yds consistantly. I have a dedicated seating die just for this bullet that is locked down tight with a Hornady upgraded lock ring on the RCBS die so I never lose the seating depth. It is what it is but I dont know why it is ,,, Far be it for me to try an outsmart that kiind of performance.

Dawgdad · Posted: Mon Dec 31, 2012 8:50 am Post subject: Re: What gives on the ogive??

chambered221 wrote:

Dawg..... I use a RCBS precision mic, it's point of measure is just in front of the bearing surface, (at approx. .236) not the ogive.
Any inconsistencies I get with the ogive and OAL will also show up here, that's how I originally discovered the box with 4 different ogives.
That box of bullets varied by as much as .012 in overall loaded cartridge length but varied only .001 in actual bullet length.
This leads me to believe that the position of the base and bearing surface of the bullet when seated varied .012 as well. Thus changing the amount of jump.

Hmmm, That is exactly bass ackwards of what I have experienced with hollow points. the BT design should lend it self to being a bit more consistent.

I was having some problems with bullet tips occaisionally dragging in the magazine and saw a large variation in OAL. I use the Hornady Comparator tool and measured Sierrra, Nosler nad Hornady hollow point match bullets and found that in all brands the base to ogive on the bullets varied less than 0.001" while the base to tip length was .010-.014". This translates to all of the difference being from ogive to tip. When you load these into a case, they are seated by the open ended stem and the ogive to tip variation showed up as - a 0.012" spread in OAL.

Since then I grab about 20 bullets from a lot (I get 1000 at a time of the same lot) find the longest of the bunch and use that to set the seater to be sure that all will be shorter than maximum mag length.

fnuser · Posted: Mon Dec 31, 2012 3:08 pm Post subject: Re: What gives on the ogive??

10spotterminator wrote:

YEP !

Just when I get too retentive about this stuff I get a load like the one for my 300 Winny using Barnes 168 gr TSX "MATCH" bullets . The OAL as well as the measure to the ogive are all over the place by as much as .017 but this load shoots inside of 1 inch at 200 yds consistantly. I have a dedicated seating die just for this bullet that is locked down tight with a Hornady upgraded lock ring on the RCBS die so I never lose the seating depth. It is what it is but I dont know why it is ,,, Far be it for me to try an outsmart that kiind of performance.

yes sir stick with what works no matter how ugly

chambered221 · Posted: Mon Dec 31, 2012 9:03 pm Post subject: Re: What gives on the ogive??

Dawgdad wrote:

Hmmm, That is exactly bass ackwards of what I have experienced with hollow points.

I've ran into that too !!!

They do make meplat trimmers to uniform the lengths.

Dawgdad · Posted: Tue Jan 01, 2013 1:45 pm Post subject: Re: What gives on the ogive??

Waste of time and money IMHO - the jump to the lands is what need to be consistent. Other than fittng in the magazine OAL is not that critical to my results.

PaulS · Posted: Wed Jan 02, 2013 12:59 am Post subject: Re: What gives on the ogive??

The jump to the lands doesn't seem to make any difference in my rifles with my loads but thats what makes reloading so much fun, different things work for different guns and people.

Bushmaster · Posted: Wed Jan 02, 2013 8:31 am Post subject: Re: What gives on the ogive??

I have a .010 jumb in the Browning .30-06 and it works just fine...

Dawgdad · Posted: Wed Jan 02, 2013 8:57 am Post subject: Re: What gives on the ogive??

I do not totally disagree Paul. If your seater die makes the bullets all the same length to the ogive they will all jump the same. Some rifles do not care what distance that is but you will get better precision if they are all the same jump than if you had random lengths of jump in a lot.

Some loads and rifles jump does matter - I used Hornady A-max and had about 0.005" sweet spot form 0.010" to 0.015" jump where I had a half moa load at 300 yards, out side that sweet spot I had a shotgun pattern.

I switched to Noslers 80 gr and they are much less sensitive about how far the jump is. I get good groups from 0.005-0.025" and probably more but that is all I tested. But you can see the difference in point of impact when you have a large difference in the length.

chambered221 · Posted: Wed Jan 02, 2013 1:21 pm Post subject: Re: What gives on the ogive??

Just a added note to the subject !!!

There's a lot of emphasis put on the ogive when discussing seating and jump. Not that it isn't important it is. More importantly though is the bearing surface of the bullet, this is what comes in contact with the bore and rifling.

In a .243 caliber barrel the bore diameter is .237 which explains why the RCBS precision mic takes it's reading from that position.

This reference point is what determines the jump not the ogive. This is where you obtain the consistent jump that Dawgdad references.
I believe most here know this but I've came across a lot of re-loaders in the past that needed this explained to them.
For some reason I felt the need to explain it here.