bullet weight and bering surface

[mitchellchandler_au]

Hi all,

Just wondering if anyone can give me some sort of guidelines to what sort of variation can be tollerated in reguards to bering surface and weight variation.
I normally dont shoot past 600yards with my 6mmbr using the 105 A-MAX.

thanks, your help wil be much appreciated.

 

[Clarence]

Mitch:
I can give you what I will accept in my Palma loading if that will help ya.
I allow .001 in bearing surface as measured from Base to Ogive
I allow one tenth in weight within a Lot of,to be fired) loads, I also weigh the loaded rounds and go in an assending fashion or from light to heavy and I watch the elevation during the string. you need to understand that I am Paranoid about loading ammo.

Clarence

 

[Cheechako]

I also weigh the loaded rounds and go in an assending fashion or from light to heavy and I watch the elevation during the string.Clarence

Clarence

Interesting. I do the same thing with my long range Benchrest ammo. I have shot them both ways - light to heavy and heavy to light- and haven't noticed any difference. have you??? Of course, in BR you have sighters between each target and can make adjustments then if needed.

Mitch, hope you don't mind me hijacking your thread for this question.

Ray

 

[Clarence]

Chee
I have noticed a creap upward in a 15 or 20 shot string but it is mostly just out of the waterline about 2", so when it starts to go up I just click a quarter or half down. I also sort cases by .1gr yes I am Paranoid but it never hurt's.

Clarence

 

[mikecr]

Brass order shooting..
Y'all are silly.
Why not just measure & mind H2O capacity of your cases?
Wouldn't it be easier to KNOW what your velocities are going to be -every shot?

Bullets
I'm all for precision,and toys), but I can't see gain in discerning bullet weight or bearing length for medium ranges. If you really need to get ES down, BL sorting might help. If you coat bullets,WS2), BL won't matter regardless.
Total weight variance will be very very small for sure.
Now spinning bullets on a Juenke may reduce groups for ya.

 

[Cheechako]

Brass order shooting..Y'all are silly.

Mike

A couple of random notes.

I sort by loaded weight for 1000 yards but not for 600 where I shoot a 6PPC for most matches. For the PPC I sort/weigh nothing.

Sorting by H2O is a very time consuming chore and one that I would not look forward to. I think that sorting empty brass by weight, weighing charges, and sorting loaded weight is enough work as it is.

For disciplines where ammo is issued to the competitors, sorting by loaded weight is about the only alternative the shooters have open to them. From reports I have read, it works

I agree that all this stuff may be a waste of time but the mental aspect should not be ignored. If you think it works, it probably will.

JMHO

Ray

 

[aJR]

Another Silly One,ME, I think all of my competitors should have your attitude Mikecr,it just makes it flat easier to win.. I don't coat bullets or use a Juenke and seem to get my share of trophy's,then i check bullets and cases to a fine degree ..But i would never call another shooter names because i don't agree with ya ..Mind you if i ever got soundly beatin by by someone using your process then i might just change my mind..JR..Jeff Rogers................

Brass order shooting..
Y'all are silly.
Why not just measure & mind H2O capacity of your cases?
Wouldn't it be easier to KNOW what your velocities are going to be -every shot?

Bullets
I'm all for precision,and toys), but I can't see gain in discerning bullet weight or bearing length for medium ranges. If you really need to get ES down, BL sorting might help. If you coat bullets,WS2), BL won't matter regardless.
Total weight variance will be very very small for sure.
Now spinning bullets on a Juenke may reduce groups for ya.

 

[mikecr]

Ray
Didn't realize you had to use someone else's ammo..Makes sense then. I've found that brass weight doesn't always correlate well with capacity though. Depends on the brand/lot/cartridge. You probably know that well. I only weigh brass as part of initial culling, before further case preps. After fire forming, for me, it doesn't take long to measure capacity of cases, and set aside those with the enough departure to raise my ES. The cutoff is easy to determine using QuickLoad.


aJr
I didn't call anyone names.
You don't know a thing about me or my process.
And last, I could care less about your trophies, or how much you shoot&shoot&shoot to get them. So you're welcome to impress someone else with all that. Sorry

 

[aJR]

Y'all are silly.

.

Sorry Mike, It's probably a language barrier problem,Where i come from,"You are all silly" is a derogatory term for a bunch of people with limited intelligence,sort of like name calling, my mistake..And last but not least,i assure you that i was neither trying to impress you or learn from you, once you close the cover on a book it's impossible to learn anymore..JR..Jeff Rogers

 

[Clarence]

aJR
While I got ya here have you found that .001 to .002 is ok for the base to ogive, any harm in using that range in a lot, and I don't think ya have a language barrier here.

micar Sir: if you shoot close range as in 600 yards then you may not be bound by the excelence of ammo process, and no one can tell me that to not weigh brass is OK.

Clarence

 

[aJR]

Hi Clarence, I can shoot the difference at .002 in a blind test with a jump but not a jam,that said i still rum .001 or less on Bearing Surface/Base to Ogive at 2 points,30 cal =.300dia and .200dia)..Testing with a Tensioned Barrel gun will change your outlook on what does and does not affect the vertical dispersion 1000yds.. There is more than one way to get the desired performance,try it if it works for ya,beaut, if not move on to something else.. This method netted me a 2.50inch 5 target agg at 551yds this year..JR..Jeff Rogers....................

aJR
While I got ya here have you found that .001 to .002 is ok for the base to ogive, any harm in using that range in a lot, and I don't think ya have a language barrier here.

micar Sir: if you shoot close range as in 600 yards then you may not be bound by the excelence of ammo process, and no one can tell me that to not weigh brass is OK.

Clarence

 

[mikecr]

"We already said the 215.2 grain bullet had a 0.615 bc so now we take the 214.7 bullet and get 0.615,214.7/215.2)=0.6485"

Lynn, you said a 216gr bullet had .615BC, not 215.2gr. I guess a Clinch River.
Also, BC would not follow that formula. It would take a pretty significant weight change to increase BC from .615 to .648. In your example here, using McDrag and or JBM's point mass program I get BC of .612 for the 214.7gr bullet, given 615@216gr, and assuming only weight is varying. For the 215.2gr BC only climbs to .613. So .001BC change here.
About as significant as common bullet weight and bearing surface variance. And it Looks to me that you'd have to increase weight to 227gr to push BC all the way up to .648

Now adding up the minor factors,and others like neck tension), might improve performance by .1moa. I don't know if this would provide an edge at 600, or even 1000, given the moa of shooting consistantly needed to win.
Nothing wrong with minding it I guess.

 

[aJR]

One of the areas that i check on a bullet is the base to ogive,but at 3 different locations.. I checking a bullet as good as the 187BIB is i have found a correlation between bullet weight and the ogive dia .. I check from base to ogive at land dia,.300),then at seating cone dia,.200) and at a step in between at.250 ..The BIB is far superior to factory bullets in it's exterior shape but what becomes evident as your batching is the the heavier bullet becomes larger in dia as you progress up the ogive ..A BIB that weights at 187.3 will be pushed further into the case by the seating cone than one at 186.9,the tests i ran were that the different dia resulted in an total loaded round AOL difference of .004,this equated to a change of a approx 2ins of elevation at 1000yds in my gun..Henry C said that this was more probably caused by the changes in it's BC,because of shape)rather than the position in the case..Long story short i can now load ALL the competition rounds i take to the range to within .001 total AOL and the weight has an influence..JR..Jeff Rogers