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Confused - Two different Sierra .308 175gr HPBT ?

nimoz

nimoz

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Minuteman
Nov 15, 2009
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North Kali
I have come across two distinctly different bullet shapes
- both from 2275c marked boxes, once in a 2275.
- all bullets in each box seems to be the same
- one is longer and slimmer
- one is distinctly fatter
Both way 175gr
A RCBS micrometer shows on as -0.010 and the other as 0.003, when having the same OAL of 2.807

I have searched and not found anything anywhere.

Assuming that they can't have the same bc - which one is the right one?
My bet would be the fatter one, as that has been the majority - but I have no idea.

Thoughts?
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

No, 2275 is 30 Cal 175gr SMK in 100 ct box
2275C is 30 Cal 175gr SMK in 500 ct box.
No different bullet.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Please explain your micrometer measurements a little better. What do you mean one measures -.010" and the other is .003?

If you're measuring the length of the bullets, you'll get a +/- .006 or .007 variance (.015" or so extremem spread on bullet length). This is common for SMK bullets, as the meplat isn't terribly uniform.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Are one type a little dull from age? Maybe if you throw them in the tumbler and get the light to reflect off of them the same they will look the same. Are one type a little dull from age?
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Please explain your micrometer measurements a little better. What do you mean one measures -.010" and the other is .003?

If you're measuring the length of the bullets, you'll get a +/- .006 or .007 variance (.015" or so extremem spread on bullet length). This is common for SMK bullets, as the meplat isn't terribly uniform. </div></div>

This is the RCBS micrometer tool:
RC88329_med.jpg


It measures to SAAMI length to the ogive.
So one bullet is 0.013 short then the other to this point, when equal in OAL.

I will see if I can get that on a photo.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Brand new bullets.
- Two friends shared a shipment for 500 bullets each and their contents was different; one shorter/fatter and the other slimmer/taller.

I also compared measurements:
Federal GMM 175gr - OAL: 2.797 Ogive: -0.010
My homeloads 175gr - OAL 2.807 Ogive: 0.003
Friends 175gr - OAL 2.807 Ogive -0.010
Conclusion: My bullets and Federal's are close in ogive shape, but my friends bullets are different.

My friend was using my press and my settings didn't work - his lengths didn't match mine.
Didn't make any sense until we could see that the bullets were different.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Please explain your micrometer measurements a little better. What do you mean one measures -.010" and the other is .003?

If you're measuring the length of the bullets, you'll get a +/- .006 or .007 variance (.015" or so extremem spread on bullet length). This is common for SMK bullets, as the meplat isn't terribly uniform. </div></div>

This is the RCBS micrometer tool:
RC88329_med.jpg


It measures to SAAMI length to the ogive.
So one bullet is 0.013 short then the other to this point, when equal in OAL.

I will see if I can get that on a photo.
</div></div>

I didn't know there was a SAAMI spec for base to ogive. Where do you see that on the SAAMI .308Win print? I know there is a minimum length spec for the chamber bolt face to the throat and lands but I don't see a spec for cartridge base to ogive. Can you point it out to me?
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Please explain your micrometer measurements a little better. What do you mean one measures -.010" and the other is .003?

If you're measuring the length of the bullets, you'll get a +/- .006 or .007 variance (.015" or so extremem spread on bullet length). This is common for SMK bullets, as the meplat isn't terribly uniform. </div></div>

This is the RCBS micrometer tool:
RC88329_med.jpg


It measures to SAAMI length to the ogive.
So one bullet is 0.013 short then the other to this point, when equal in OAL.

I will see if I can get that on a photo.
</div></div>

I didn't know there was a SAAMI spec for base to ogive. Where do you see that on the SAAMI .308Win print? I know there is a minimum length spec for the chamber bolt face to the throat and lands but I don't see a spec for cartridge base to ogive. Can you point it out to me?
</div></div>

My fault; the tool uses ANSI spec for shoulder - not SAAMI.
I assumed that the zero for lands measurements (what I call ogive) reflect the same standard - although I have no idea what they picked as zero, and that is not my point with this posting.
Question still stands: Why are bullets from the same manufacturer available in two different shapes, although marked the same.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

The answer, from what I can tell, is that you are using a tool that measures from base to ogive, and assuming that the OAL would be the same. The bullets should be pretty consistent from base to ogive, with quality seating die, but the tips give an inconsistent OAL measurement.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body">
I didn't know there was a SAAMI spec for base to ogive. Where do you see that on the SAAMI .308Win print? I know there is a minimum length spec for the chamber bolt face to the throat and lands but I don't see a spec for cartridge base to ogive. Can you point it out to me?
</div></div>

My fault; the tool uses ANSI spec for shoulder - not SAAMI.
I assumed that the zero for lands measurements (what I call ogive) reflect the same standard - although I have no idea what they picked as zero, and that is not my point with this posting.
Question still stands: Why are bullets from the same manufacturer available in two different shapes, although marked the same. </div></div>

I didn't know that there was an different ANSI spec for the .308 Winchester. Aren't the ANSI and SAAMI specs for a .308 Winchester round the same? If not can you direct me to the ANSI specs for a .308 Winchester round?
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body">

I didn't know that there was an different ANSI spec for the .308 Winchester. Aren't the ANSI and SAAMI specs for a .308 Winchester round the same? If not can you direct me to the ANSI specs for a .308 Winchester round?


</div></div>

I'm afraid not - You are asking the monkey with the wrench for the blueprint of the tool
smile.gif


Googling I found Z299.4-1992 - and that SAAMI is part of ANSI: http://www.saami.org/specifications_and_information/publications/download/206.pdf

Again, I don't question the specs - just a product.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Not sure if this is visible to the eye, but the right one is longer and narrower at the top.

photo%283%29.JPG
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

my understanding of the manufacturing process is that there are several machines belching out these thing ....and they all feed into one hopper......then on to inspection, and packaging, and then out the door.......

one of them boolits was made on a friday....i can tell
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Teggy1</div><div class="ubbcode-body">what is the actual measured diameter of both?</div></div>
Same .308 - my micrometer has them both equal just above the boat tail.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body">Not sure if this is visible to the eye, but the right one is longer and narrower at the top.

photo%283%29.JPG
</div></div>


Maybe they are from different batches. I got a few hundred 178 and 168 grain AMAXs that had different packaging then my old ones. They are the AMP versions and they are much more consistent in overall length and where the ogive is relative to the base, MUCH more consistent. Bullet weight seems to be a lot more consistent too compared with the older batch. I started out with the older AMAX bullets and now they are all coming in with AMP marks on the cases.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body">


Maybe they are from different batches. I got a few hundred 178 and 168 grain AMAXs that had different packaging then my old ones. They are the AMP versions and they are much more consistent in overall length and where the ogive is relative to the base, MUCH more consistent. Bullet weight seems to be a lot more consistent too compared with the older batch. I started out with the older AMAX bullets and now they are all coming in with AMP marks on the cases. </div></div>

Probably different batches, but I have gone through several boxes/batches and never seen this before.
- My friends buy two 500-boxes and one is different.
- Previously one bought a 100-pack to test and they were also different.
So with their frequency of finding the issue, I would expect that more would have noticed.

I never shot a mix of the bullets, so I have no idea if they behave differently. I would believe that they do, given that you can see the difference with your eye - but then I may not be consistent enough to tell
smile.gif


Anyway, someone else may spot it in the future and there is at
least something to google.

Cheers,
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body">
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body">


Maybe they are from different batches. I got a few hundred 178 and 168 grain AMAXs that had different packaging then my old ones. They are the AMP versions and they are much more consistent in overall length and where the ogive is relative to the base, MUCH more consistent. Bullet weight seems to be a lot more consistent too compared with the older batch. I started out with the older AMAX bullets and now they are all coming in with AMP marks on the cases. </div></div>

Probably different batches, but I have gone through several boxes/batches and never seen this before.
- My friends buy two 500-boxes and one is different.
- Previously one bought a 100-pack to test and they were also different.
So with their frequency of finding the issue, I would expect that more would have noticed.

I never shot a mix of the bullets, so I have no idea if they behave differently. I would believe that they do, given that you can see the difference with your eye - but then I may not be consistent enough to tell
smile.gif


Anyway, someone else may spot it in the future and there is at
least something to google.

Cheers, </div></div>

The difference I saw between the Hornady bulets may have been the old bullet manufacturing Hornaday used and their new AMP process, there are pretty measurable differences between the old and new processes. Like I posted above the new AMP processed bullets I scaled, measured OAL and ogive height on are all much more consistent then any of the old type manufacturing process. The new AMP stuff is very nearly perfect from bullet to bullet with about 1 in 10 being a little bit different. This is a LOT better than the Sierra 168 and 175 MatchKings I still use which seem to vary a lot bullet to bullet even within a single lot. The SMKs in 30 cal. I have been measuring seem to have alarming differences in weight and ogive height but somehow still seem to fly pretty consistently. But the jury is still out around here at my house on how well the new AMP Hornaday Match bullets fly.



 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nimoz</div><div class="ubbcode-body">Brand new bullets.
- Two friends shared a shipment for 500 bullets each and their contents was different; one shorter/fatter and the other slimmer/taller.

I also compared measurements:
Federal GMM 175gr - OAL: 2.797 Ogive: -0.010
My homeloads 175gr - OAL 2.807 Ogive: 0.003
Friends 175gr - OAL 2.807 Ogive -0.010
Conclusion: My bullets and Federal's are close in ogive shape, but my friends bullets are different.

My friend was using my press and my settings didn't work - his lengths didn't match mine.
Didn't make any sense until we could see that the bullets were different. </div></div>


Oh, I forgot to ask, did you put them on a scale? I don't have data for Sierra MK in 168 and 175 but Hornady AMAX 168 and 178 bullets externally look almost the same but the OAL is just a tiny bit shorter on the 168 grain slugs. ALso interesting is that the ogive heights on the AMAX 168 and 178 are identical.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Not to come in late on this but Sierra runs QA by lots. All of a certain bullet will fall into a specification for that bullet but consistancy with in the lot is a tighter specification than the overall catalog description. As stated earlier the "c" is a 500 round box, as opposed to using two different model #'s for the same bullet. 1477 and 9377 for 77 grain SMK or 1478 and 9378 for the 77 with canalure. I could be mistaken, but I don't think the 175 is available with a canalure.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body">

Oh, I forgot to ask, did you put them on a scale? I don't have data for Sierra MK in 168 and 175 but Hornady AMAX 168 and 178 bullets externally look almost the same but the OAL is just a tiny bit shorter on the 168 grain slugs. ALso interesting is that the ogive heights on the AMAX 168 and 178 are identical.

</div></div>
Same weight exactly
smile.gif

- Just compared a few.

I have solely loaded SMK 175, SMK 168 and Scener 155
- Did not save money or powder using SMK 168, so I'm not loading them anymore.

Both SMK 175 and Scenar 155 have served me well for long range - out to 1,200y, with the Scenars being less sensitive to wind - but that could be just my loads.

I have looked at AMAX, but they are as expensive as the SMK 175.
I would make a load for sub 500y, if I could find a bullet that is consistent and cheap - 15c/rnd?

I would probably look a lot harder if I were shooting a .338
grin.gif
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunsnjeeps</div><div class="ubbcode-body">Not to come in late on this but Sierra runs QA by lots. All of a certain bullet will fall into a specification for that bullet but consistancy with in the lot is a tighter specification than the overall catalog description. As stated earlier the "c" is a 500 round box, as opposed to using two different model #'s for the same bullet. 1477 and 9377 for 77 grain SMK or 1478 and 9378 for the 77 with canalure. I could be mistaken, but I don't think the 175 is available with a canalure. </div></div>

Thank you - I do see that they are uniform per box - no complaints there, just did not expect the big die-adjustment between boxes.
- Don't think they print lot number on their boxes?
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

I went to a new box of 500 175smks recently and the Ogive was taller on these bullets than the previous... I had to lower (push the bullet into the case more) the seating die down by .015-.020 to get the same OAL to Ogive as my other rounds
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Thanks, I'm not alone!
- Yes, that's my issue although I may not have described as clearly and concise
smile.gif


Let me know how they shoot for you.
- I don't expect them to be bad, but if they are different - they can't have equal bc?


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jason_B</div><div class="ubbcode-body">I went to a new box of 500 175smks recently and the Ogive was taller on these bullets than the previous... I had to lower (push the bullet into the case more) the seating die down by .015-.020 to get the same OAL to Ogive as my other rounds</div></div>
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

ive been ocd measurin 175 smk's for awhile because i buy blems by the pound from their outlet. i sort them into "like piles" to be loaded into seperate batches that more closely match each other so as to achieve consistent results from basically inconsistent blems. what i notice is that in general i end up with 3 piles. short fat ones, long skinny ones, and then just way out there ones. i measure oal,base to ogive, and weight. my guess is that my pile one and my pile 2 come off 2 different machines from their setups and that the way off ones are just f-ups.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: marduk185</div><div class="ubbcode-body">ive been ocd measurin 175 smk's for awhile because i buy blems by the pound from their outlet. i sort them into "like piles" to be loaded into seperate batches that more closely match each other so as to achieve consistent results from basically inconsistent blems. what i notice is that in general i end up with 3 piles. short fat ones, long skinny ones, and then just way out there ones. i measure oal,base to ogive, and weight. my guess is that my pile one and my pile 2 come off 2 different machines from their setups and that the way off ones are just f-ups.</div></div>

Thanks for sharing.
Two questions:
1. Do you see a difference in accuracy/speed and usable distance between the two skinny/fat piles?
2. Relative size of the piles?

Thanks,
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

The 2275 "C" is the centimeter version. It is meant to be fired in .762 centimeter rifles only. Also, they can only be used with centimeter metric scopes.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

awesome.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

nimoz, i havent shot enuf data stream to say. ive only so far been load developing the long skinny pile but they seem to be same size piles and the fup pile is smaller than the other two. real scientific i know...
i can say that what ive loaded have been super consistent shooters after this selection process.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

Time to start sorting by bearing surface length. I believe the ogive to tip is the least important measurement. I sort 80 grain SMK's and usually have a bearing surface spread of about .010-.015 in a 500 box, with most falling into 3 or 4 distinct groups. I also seat everything about .020 long remeasure and sort and seat a second time because the I've found seating depth to be fairly critical.
 
Re: Confused - Two different Sierra .308 175gr HPBT ?

I just made the observation that Lapua 155 Scenars also differ between batches.

My new loads with 0.020 length to the ogive are longer than my old batch that are 0.030 to the ogive.
- My new loads seem slightly better, but that doesn't matter as the next batch may be different again
frown.gif

 
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