Is there really THAT much difference in ogive??

bruddah

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I bought 300 175gr BTHP blems from Grafs awhile back. I assume they are Sierra Matchkings because the sectional density and ballistic coefficient match to a "T".

When setting up some loads to test out (varying charge weights), I adjusted the seater die so that the ogive was .010" off the lands. Set up my first loaded cartridge, and thought I was good to go. However, the second cartridge measured about .007"-.008" shorter than the first one I set up. This concerned me a little bit so I continued to measure every singe cartridge after that. to my dismay, they all seemed to vary in length. At first I thought the RCBS seater die was not doing a reliable job so I set up the Lee seater die and tried a few more. Same results.

Measurement to the lands with this particular bullet is 2.209". I set up the first cartridge to measure 2.200" to the ogive. The cartridges varied (regardless of seating die) average from 2.203" to 2.192" without me touching the seating adjustment.

This leads me to believe there is inconsistency from bullet to bullet as far as the shape goes. I know these were sold as blems, but should there be that much difference in measurement?

This also begs the question of whether or not the difference in length will affect my ability to do a proper OCW or even accuracy check.

Will a seating difference varying by around .010" from cartridge to cartridge affect my ability to shoot small groups, or is this too small of a variance to worry about?

I did separate them by OAL (to ogive) as I was loading and measuring so that I have at least three cartridges of the same powder charge and same length to the bearing surface.

Is this unacceptable, or am I being too picky?

Furthermore, I thought blems were just cosmetic in nature.

Thanks for any input.
 

JGorski

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From some of the bullets I've checked as far as ogive length I usually get within .001 from one bullet to another, .003"doesn't sound too awfully bad, maybe sort them according to ogive lengths if it would make you feel better.
 

pmclaine

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    I use a Hornady comparator and try my best to get consistent reads on a bunch of things.

    Ill dick with my size die to get perfect shoulder bump than when it comes to seating I fiddle with that process to attain nirvana.

    Thing is its never exact. Ive come to the conclusion that by definition of what I am doing I wont ever reach perfection. My brass has been fired. In the case of my semi autos it has been ripped from a chamber by an extractor claw and tossed 5-10 feet to my left. In the case of my Garand that gun does a sadist trick of tearing the case from the gun than it whacks the brass while spinning in mid air with the op rod to chuck it forward.

    Most of my brass has some sort of rim damage/bending and I think this is the reason for small variances in finished product. I take an average of 5-10 loaded rounds and if that average is on target I call it good. Perhaps I am failing because I use the Hornady anvil to measure against. I guess I could measure off the blade of my caliper and rotate the case so that any rim damage could not affect my measurement. Im not willing to do that though until I can shoot well enough that it will make a difference.

    Virgin brass or bolt gun brass maybe the tolerances should be tighter.
     

    pmclaine

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    Do you have the adjustable gas port on the M1?

    Negative. Its GI. Operates fine. Im on my 4th loading with some KA brass that gets shared between the M1 and a pair of 03's. If I can get 5 loadings (and I expect I will get more) that brass owes me nothing. Cant see the need for the adjustable gas port unless I want to use some heavy bullet commercial. My loads are 4064/Varget in the 46-47 range with a 168 HPBT.
     

    Bradu

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    I have had that kind of variance as the op on non blemished bullets on two different kind of match bullets out of the same box. I don't know how much of a difference it makes but I'm not worried about benchrest type accuracy.
     

    mdmp5

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    I bought 300 175gr BTHP blems from Grafs awhile back. I assume they are Sierra Matchkings because the sectional density and ballistic coefficient match to a "T".

    When setting up some loads to test out (varying charge weights), I adjusted the seater die so that the ogive was .010" off the lands. Set up my first loaded cartridge, and thought I was good to go. However, the second cartridge measured about .007"-.008" shorter than the first one I set up. This concerned me a little bit so I continued to measure every singe cartridge after that. to my dismay, they all seemed to vary in length. At first I thought the RCBS seater die was not doing a reliable job so I set up the Lee seater die and tried a few more. Same results.

    Measurement to the lands with this particular bullet is 2.209". I set up the first cartridge to measure 2.200" to the ogive. The cartridges varied (regardless of seating die) average from 2.203" to 2.192" without me touching the seating adjustment.

    This leads me to believe there is inconsistency from bullet to bullet as far as the shape goes. I know these were sold as blems, but should there be that much difference in measurement?

    This also begs the question of whether or not the difference in length will affect my ability to do a proper OCW or even accuracy check.

    Will a seating difference varying by around .010" from cartridge to cartridge affect my ability to shoot small groups, or is this too small of a variance to worry about?

    I did separate them by OAL (to ogive) as I was loading and measuring so that I have at least three cartridges of the same powder charge and same length to the bearing surface.

    Is this unacceptable, or am I being too picky?

    Furthermore, I thought blems were just cosmetic in nature.

    Thanks for any input.

    Here is my own input from experience. It is not the variations in ogives in bullets that cause the differences in seating. It is the fact that the seater doesn't seat from the ogive. It seats from above the ogive, as the point of the bullet goes into the sleeve. If it was seating from the ogive, then there would be consistent seating depth regardless of imperfections. Just because you set the seater for one length, it has no bearing on the seating depths of the next bullet.

    If you want exact seating depth based on the ogive for a bunch of rounds, you need to do this: seat the bullet long, measure, make the necessary adjustment, then seat again. It can be a pain in the ass, but I use a redding comp seater and an instant indicator mounted on a t7 turret press. I can do this operation pretty fast this way, and I get variations in seating less than .001 without a lot of effort. If you are super meticulous, you can get variance as low as your indicator dial will read.
     

    todd

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    Here is my own input from experience... If you want exact seating depth based on the ogive for a bunch of rounds, you need to do this: seat the bullet long, measure, make the necessary adjustment, then seat again... If you are super meticulous, you can get variance as low as your indicator dial will read.

    +1 Takes a little longer, but builds more consistent rounds
     

    Unknown

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    I bought some pulls a while back, and apparently the way the bullet is gripped to pull it out of the case crushes the lead enough that trying to get any consistency in the ogive length , and overall length for the bullets was impossible. I had to measure every bullet, and separate them by length to ogive, they reseat the bullets to get any consistency. I dont' care as much about overall length as long as the rounds fit into a magazine, but having inconsistent ogives gives inconsistent accuracy. Many bullets that I seated were off by as much as 40 thousandths...
     

    Unknown

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    The pulls (much different than seconds) didn't shoot that well because with the ogive being all over the place, my pressures and velocities were also all over the place. Since going through the batch (about 850 rounds) and reseating the various bullets to have the ogive at the same point, accuracy has improved, but it still isn't as consistent as "first quality" bullets.

    Everyone has to decide for themselves if the extra work is worth the savings.
     

    BuzzBoss915

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    Maybe I'm a snob, but blems and accuracy work are not compatible.

    I had a tour of Sierra when they were in Santa Fe Springs years ago. Typical machine shop.

    But, they discard a few in set up, and some are dropped in the wrong bin and others are swept off the floor. Some have dimensional problems, others might be off in weight, some might not have the final polish, stuff like that.

    If you want performance, buy premium bullets. Overall length is demonstrably meaningless and the manufacturers will tell you that it varies; using the closest tolerances in the Industry. So, go by your comparator. BB
     

    SWThomas

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    I just went through 3 boxes of SMK 175s and got those same variations. I just separated them into three groups. Each groups has bullets that are +\- 0.004 from each other.
     

    boone3380

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    How much powder is in the case. If the case is pretty full, you will get inconsistent seating depths.
     

    nuclear_shooter

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    There is no advantage in measuring bullets, based on over all length. BB

    I'm not saying you're wrong, but I'd like to know more about this. Why is there no advantage? Wouldn't there be slight variations in BC? Probably doesn't matter much I guess.
     

    1slow01z71

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    I'm not saying you're wrong, but I'd like to know more about this. Why is there no advantage? Wouldn't there be slight variations in BC? Probably doesn't matter much I guess.

    Especially hollow points the bullet length varies so the COL is not necessarily indicative of where the ogive actually is from the case head. This is where the hornady comparator set comes in handy if youre really trying to control the exact jump to the lands. I too have noticed some difference in length to ogive for my 300WM loads, as much as .008 which could be problematic since Im only loading .01 off the lands. Ive been measuring my ogive length then adjusting with my forster micrometer seater. A turret head press with an instant indicator would be awesome but Im not convinced that a few thousands one way or the other makes whole lot of difference. Especially with a bullet that likes to jump. With more testing, if I do find it makes a noticeable difference in accuracy I will buy a T7 and instant indicator for my precision loading needs.
     

    bruddah

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    How much powder is in the case. If the case is pretty full, you will get inconsistent seating depths.
    Not the reason for inconsistency in this case. These different reading were from low charges up to the higher ones. I've seen where the bullet seat further out as you compress a charge. This however was not one of those phenomenon.

    There is no advantage in measuring bullets, based on over all length. BB
    Not sure if you're addressing me or not, but I was measuring to the ogive not the tip.
     

    bruddah

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    Blems are all over the place! You get what you pay for.
    I thought blems were purely cosmetic in nature, and did not affect performance?

    Here is my own input from experience. It is not the variations in ogives in bullets that cause the differences in seating. It is the fact that the seater doesn't seat from the ogive. It seats from above the ogive, as the point of the bullet goes into the sleeve. If it was seating from the ogive, then there would be consistent seating depth regardless of imperfections. Just because you set the seater for one length, it has no bearing on the seating depths of the next bullet.

    If you want exact seating depth based on the ogive for a bunch of rounds, you need to do this: seat the bullet long, measure, make the necessary adjustment, then seat again. It can be a pain in the ass, but I use a redding comp seater and an instant indicator mounted on a t7 turret press. I can do this operation pretty fast this way, and I get variations in seating less than .001 without a lot of effort. If you are super meticulous, you can get variance as low as your indicator dial will read.
    That makes sense. I'm still surprised the profile of the bullet would not be more consistent elsewhere along the curvature of the bullet (excluding the tip of course).
    I may just have to go back and re-seat the longer ones. I did separate by length to ogive though during the process. I have at least three of the same measurement in each powder charge so that my results will be as valid as possible.

    Maybe I'm a snob, but blems and accuracy work are not compatible.

    I had a tour of Sierra when they were in Santa Fe Springs years ago. Typical machine shop.

    But, they discard a few in set up, and some are dropped in the wrong bin and others are swept off the floor. Some have dimensional problems, others might be off in weight, some might not have the final polish, stuff like that.

    If you want performance, buy premium bullets. Overall length is demonstrably meaningless and the manufacturers will tell you that it varies; using the closest tolerances in the Industry. So, go by your comparator. BB
    Again, I was under the impression that blems were purely cosmetic in nature and in now way shape or form affected performance.

    If the blems were as good as the premiums, they would cost more. Blems are for plinking.
    See above.
     

    alexdawg

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    FYI. I was not purchasing blems. And since I am relatively new to reloading I asked them about the differences.

    My email to Sierra:

    I recently purchased 2 boxes of 100 each 175 gr Matchking BTHP in 308 from Midway USA. Product code 2275. I was surprised to find that these boxes had different OAL and ogive lengths. I had already worked up loads with yet another length bullet to get a cartridge OAL of 2.810 and ogive length of 2.124, which is what my gun likes. The 2 boxes that I am referring to cant get me to those worked up cartridge lengths.

    What exactly is the spec on these bullets?

    Box one. OAL 1.236 average ogive .505 average

    Box two. OAL 1.253 ogive .520

    My worked up loads were done with these: OAL 1.243 average ogive .550 average.


    I purchased 3 boxes at Cabelas yesterday that match closely my worked up loads.



    Their response:


    Honestly, the numbers I can give you will come from one specific lot number and obviously, you are seeing two different lots. More than likely, these were made by two different people on two different machines using different dies. It doesn’t mean that the quality is bad on one or the other; it just means there will be slight variations from box to box. Within the box, it would have been +/- 0.3 grain in weight and +/- 0.0003” in diameter at the pressure ring and as I know this doesn’t reflect the length, I have seen it not matter at all, as long as I’m not adjusting my seating die for every round to get the same COAL. It would be worth your while to at least try them in your firearm, you may be pleasantly surprised.
     

    BuzzBoss915

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    "the impression that blems were purely cosmetic in nature"

    I would love to believe that, but understanding the way QUALITY CONTROL works, and that some of these bullets are rejected somewhere along the process, not just because they may be tarnished. There can be dimensional problems and it's possible the weight is out of spec. It's also possible that you are buying mixed lot numbers, in fact, very likely.

    All this does not mean they won't shoot to where they are pointed. It's all about duplicating a bullet as near as possible X number of times. I want perfection but I will settle for the best they can do. Not, their fuck ups. BB
     

    bruddah

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    FYI. I was not purchasing blems. And since I am relatively new to reloading I asked them about the differences.

    My email to Sierra:

    I recently purchased 2 boxes of 100 each 175 gr Matchking BTHP in 308 from Midway USA. Product code 2275. I was surprised to find that these boxes had different OAL and ogive lengths. I had already worked up loads with yet another length bullet to get a cartridge OAL of 2.810 and ogive length of 2.124, which is what my gun likes. The 2 boxes that I am referring to cant get me to those worked up cartridge lengths.

    What exactly is the spec on these bullets?

    Box one. OAL 1.236 average ogive .505 average

    Box two. OAL 1.253 ogive .520

    My worked up loads were done with these: OAL 1.243 average ogive .550 average.


    I purchased 3 boxes at Cabelas yesterday that match closely my worked up loads.



    Their response:


    Honestly, the numbers I can give you will come from one specific lot number and obviously, you are seeing two different lots. More than likely, these were made by two different people on two different machines using different dies. It doesn’t mean that the quality is bad on one or the other; it just means there will be slight variations from box to box. Within the box, it would have been +/- 0.3 grain in weight and +/- 0.0003” in diameter at the pressure ring and as I know this doesn’t reflect the length, I have seen it not matter at all, as long as I’m not adjusting my seating die for every round to get the same COAL. It would be worth your while to at least try them in your firearm, you may be pleasantly surprised.
    Good to know. Thanks for sharing. I will definitely be interested in how they group.


    "the impression that blems were purely cosmetic in nature"

    I would love to believe that, but understanding the way QUALITY CONTROL works, and that some of these bullets are rejected somewhere along the process, not just because they may be tarnished. There can be dimensional problems and it's possible the weight is out of spec. It's also possible that you are buying mixed lot numbers, in fact, very likely.

    All this does not mean they won't shoot to where they are pointed. It's all about duplicating a bullet as near as possible X number of times. I want perfection but I will settle for the best they can do. Not, their fuck ups. BB
    Learn something new every day. Thanks for the info.
     

    Gary Smith

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    I have made the Camp Perry pilgrimage many times and when I lived in Az. I would stop @ Sierra on the way
    back and frequently bought 5 gallon buckets of blems/2nds that were used by the junior shooters to gain
    experience . These bullets were never as consistent as the 1st Tier and we knew that.
    This was before the 22 became de rigueur and everyone shot the 30's.
     

    bruddah

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    Ok, next I will load up some first rate SMK 175 gr bullets and see if I get the same variation.

    I don't recall getting this much variation on the 77 gr SMKs I loaded up for my SPR class earlier this year... They were premium and not blems.

    Maybe my days of buying blems are over. I'm still curious to see how they shoot. Hopefully I am pleasantly surprised.
     

    opeagle

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    A buddy and I compared his three year old 175 SMK's to my year old box. Both loads OAL were within .002 but the older box ogive measurement was consistently .005-.006 longer.