Sierra 107MK sorting results

[heath]

I just finished sorting a new box of 500 Sierra 107 match kings. Sorted from ogive to base. Here is what I found.

Qty Measurement
33 0.654
108 0.655
78 0.656
11 0.657
14 0.658
78 0.659
133 0.660
46 0.661
2 0.663
1 0.682 Wonder what happened to this one?

504 total bullets

 

[Eddie Harren]

I wonder how many point up dies Sierra uses on these bullets. I wonder what calipers you used to get your measurements. Most dial calipers, regardless of cost, are only rated to +/- .001". That is why a really accurate measurement requires a micrometer.

 

[heath]

I used a set of Starrett calipers. I was just curious as to why there was two groups. Looks like the box was a mixture of two machines.

 

[Shynloco]

Not surprising! And I agree it does appear those bullets came from two machines. I have started sorting bullets recently after finding that within just a box if 100 Sierra 85 gr 6.5 bullets, my ojive measurement after reloading, would varying by .010. So I started measuring the bullets, ojive to base and found slightly 1/3 had a difference of .010 from the rest and another 1/3 had yet another .010 added on. There were also 3 or 4 odd balls that were another .010 longer. Frankly I cannot understand why Sierra mixes the bullets from the different machines together. I've been told by a friend who also measures his bullets that Berger also mixes their bullets. I can also say that I measured about 20 Bart's 68 gr 6mm FB custom bullets from a box of 500 and they all measured the same. I guess that's part of what we pay for these days when you buy bullets. And I don't understand it.

Alex

 

[Eddie Harren]

All of Bart's bullets, in that lot & weight, are pointed up in the same die. That is only one of the great benefits of shooting custom made bullets.

 

[heath]

I can only praise Bart's bullets. I beleive they will make you shoot better groups from the time you order them. I wish he made a 6mm 105 bullet. Bibs make a fine bullet too.

 

[eric32]

Does any one have test results from base to o-give groups relating to Extreme Spread FPS?

Would a .010 difference equate to X FPS in a given caliber?

 

[UltraBR30]

Does any one have test results from base to o-give groups relating to Extreme Spread FPS?

Would a .010 difference equate to X FPS in a given caliber?

Good question but strongly feel it would equate to X amount of BC variance instead of Mv variance.
Philip

 

[eric32]

Are you saying since the bullet it self would be a bit longer than the rest . It would then translate to a sleeker bullet which would increase the BC of the that particular bullet since it was .010 longer. (For this example)

But then would the bearing surface not translate into a higher drag going down the barrel?

I am really curious about this subject since I saw the post from Bryan Litz about Base to o-give sorting giving the best overall indication of a bullet rather than the other methods

 

[rmist]

I wonder how many point up dies Sierra uses on these bullets. I wonder what calipers you used to get your measurements. Most dial calipers, regardless of cost, are only rated to +/- .001". That is why a really accurate measurement requires a micrometer.

Must be...Digital calipers !!!!

 

[Eddie Harren]

"Must be... Digital calipers"

Check the manufacturers claims as to accuracy on all calipers, regardless of cost.

 

[zx10mike]

great thread i'm just going through my 107's as we speak as such.i have found through my batch 7 tho difference and my thought was if i'm seating of the ogive the base is 7 thou further in changing inside case preasure.would this show in 100 yard groups?i find the accuracy node small with the 107 sierra were as with 105 amax i can just throw powder in .i had great accuracy with new brass with 30.2 grains of varget then it just opened up i have had to go to 30.6 to get it back on .so with this small accuracy node in mind i suspect it matters.will test myself soon as i can.

 

[madderg]

When I load, I use the section of the bullet that will engage the rifling in the throat... length has little to do with that measurement, that's where I either jam or hold back some thousands. That point of measurement never changes.

 

[trental]

I've had a box of Sierra 7mm 130 MKs mic out with 3 distinct groups of bullets all separated by 0.020" (extreme spread of 40 thou). I did a tour at Sierra a while back and brought it up to them. They said I should have sent them back. I use them for metallic silhouette so I doubt I could have realized any down range variance. It did make me take notice though.

Great, now I need to go check the 1000 107gr MKs on my shelf before I do anymore load testing with them.

 

[heath]

I have another 500 I bought at the same time. I guess I will sort them on the next rainy day and see how they measure.

 

[6fatrat]

Not surprising! And I agree it does appear those bullets came from two machines. I have started sorting bullets recently after finding that within just a box if 100 Sierra 85 gr 6.5 bullets, my ojive measurement after reloading, would varying by .010. So I started measuring the bullets, ojive to base and found slightly 1/3 had a difference of .010 from the rest and another 1/3 had yet another .010 added on. There were also 3 or 4 odd balls that were another .010 longer. Frankly I cannot understand why Sierra mixes the bullets from the different machines together. I've been told by a friend who also measures his bullets that Berger also mixes their bullets. I can also say that I measured about 20 Bart's 68 gr 6mm FB custom bullets from a box of 500 and they all measured the same. I guess that's part of what we pay for these days when you buy bullets. And I don't understand it.

Alex

Berger does not mix bullets!
Steve Bair

 

[Dusty Stevens]

Yea right

 

[BartsBullets]

I can only praise Bart's bullets. I beleive they will make you shoot better groups from the time you order them. I wish he made a 6mm 105 bullet. Bibs make a fine bullet too.

Hi Guys! First post here! I am working on a 6MM 105 grain Boattail. I'm in the testing phase right now. If all goes well they should be available soon.

Thanks
Bart
Bart's Custom Bullets

 

[heath]

Cool. I had heard rumor about these. Hopefully they will do good and be available soon.

 

[kyreloader]

I can only praise Bart's bullets. I beleive they will make you shoot better groups from the time you order them. I wish he made a 6mm 105 bullet. Bibs make a fine bullet too.

Hi Guys! First post here! I am working on a 6MM 105 grain Boattail. I'm in the testing phase right now. If all goes well they should be available soon.

Thanks
Bart
Bart's Custom Bullets

Can you give us any details about these bullets??