Last night I was trying to load some 147gr ELD-M and decided to measure a few lots that I had setting there. With this ammo drought I have just been buying anything I can get my hands one. I had 4 lots and some as much as .021 from lot to lot. Does that not sound like to much? I have no idea what the tolerance is but that sounds a little much to me. I tried checking some of my A-tips and they were much closer. Do most of you do a seating depth test for every lot of bullet you get?
Bullet length base to ogive lot to lot.
- Thread starter Andrew863
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I’ve done the same. With 178 Amax in years past I had a variation of .017 in a single box of 100 bullets.
For comparison a box of Berger’s and 168 SMK were under .003. Measured the same day with the same caliper/gauge
Lot to lot is generally going to vary. But Hornady are the worst I’ve used that vary in a single lot. I still use their 143/178/200/212 ELDX. But my target and fclass guns run Berger or Sierra
I'm in the process trying to understand why changing to a different lot of bullets increased group size.
This is on a 308 Win using a 175 hr SMK. The bullet base to ogive is different by about 0.010" from lot to lot. Within a lot the dimension is within 0.002".
I did a seating depth test with the newer lot of bullets ( in 3 thou steps ) and found that the group size went back down if I was 0.003" longer CBTO.
I'm thinking there must be more to it though since the bullet base to ogive was 10 thou different and the cartridge base to ogive ended up 3 thou different.
This is on a 308 Win using a 175 hr SMK. The bullet base to ogive is different by about 0.010" from lot to lot. Within a lot the dimension is within 0.002".
I did a seating depth test with the newer lot of bullets ( in 3 thou steps ) and found that the group size went back down if I was 0.003" longer CBTO.
I'm thinking there must be more to it though since the bullet base to ogive was 10 thou different and the cartridge base to ogive ended up 3 thou different.
Powder AND seating depth tests on a new lot#. Youre finding out why.
Thats why I dont buy little shit drops and buy one big lot thats worth my time and efforts in addition to the expense.
Can you go off of the velocity your original load was giving you? Or can the velocity end up a little different for an accurate/precise load?
Want to try an interesting experiment?
Measure the ID/Bore diameter of your comparator, crack a cold one, sit down and ponder the ramifications of the ID (probably) being significantly different (smaller) than the OD of the bullets you are measuring.
Then, give some thought to just how much a small change in bore diameter of the comparator causes a significant difference in where the comparator actually comes into contact with the profile of the bullet.
And here we (myself included) thought all along that we have been measuring Base to “OGIVE”…ha, ha, ha
Lol I have actually been down this road before. I ended making a custom modified case neck sized to where the bullet is snug but will still move to try and hold things concentric.Want to try an interesting experiment?
Measure the ID/Bore diameter of your comparator, crack a cold one, sit down and ponder the ramifications of the ID (probably) being significantly different (smaller) than the OD of the bullets you are measuring.
Then, give some thought to just how much a small change in bore diameter of the comparator causes a significant difference in where the comparator actually comes into contact with the profile of the bullet.
And here we (myself included) thought all along that we have been measuring Base to “OGIVE”…ha, ha, ha
OK. so you know then
For longer than I care to admit, I "thought" the comparator's bore was always "identical" to the bullet diameter. One manufacturer's set that I had was 5 or 6 thousandths undersized. From nominal bullet diameter to 6 thousandths under makes a huge difference as far as where the comparator gets tight on the bullet profile. The whole exercise caused me to wake up, smell the coffee and understand that CBTO or Bullet BTO is just a relative measurement. BUT........It's still a hell of a lot better than going off of COAL or Bullet OAL.
You’ll find lots of variation on Hornandy bullets
They like to disappear mid flight as well.
They like to disappear mid flight as well.
You know I have heard several people say this but have never had it happen. Is is over a certain velocity?
Along these lines of variance... while all commercial bullet lots vary in BTO measurements from lot to lot, which of the major manufacturer's vary the least in your experience?
Which ones did I miss?
Berger
Sierra
Nosler
Hornady
Barnes
DTACs
Not sure that many of us use Speer rifle bullets.
(cup and core, not lathe turned solids or customs)
Which ones did I miss?
Berger
Sierra
Nosler
Hornady
Barnes
DTACs
Not sure that many of us use Speer rifle bullets.
(cup and core, not lathe turned solids or customs)
I have started using SAC Comparators. Purportedly these have a much better “orifice ID geometry”.OK. so you know then
For longer than I care to admit, I "thought" the comparator's bore was always "identical" to the bullet diameter. One manufacturer's set that I had was 5 or 6 thousandths undersized. From nominal bullet diameter to 6 thousandths under makes a huge difference as far as where the comparator gets tight on the bullet profile. The whole exercise caused me to wake up, smell the coffee and understand that CBTO or Bullet BTO is just a relative measurement. BUT........It's still a hell of a lot better than going off of COAL or Bullet OAL.
I do find them more accurate but also tend to stick just a tad and need more precision in landing the case base correctly on the caliper. This is because they are closer to the bullet OD than the Hornady.
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