Bullet ogive variation in lots.

D

dieselgeek

Do you even Shoot Bro?
Full Member
Minuteman
Dec 1, 2010
1,423
5
Dallas, Texas
#1
Today I was loading up 100 rounds of 178 amax when one box ran out, so I started to grab another box. I measured the first round I loaded and noticed it to be a good amount longer OAL then the last round from the last box. I had 5 set aside from the 1st box so I measured from the Ogive on them and noticed this.

Lot number 211-0064
Ogive..698-700


Lot number 212-0094
Ogive .707-710


Anyone else notice that big of a difference from lot to lot? Forgive me if this is common, I'm fairly new to reloading.
 
#2
Re: Bullet ogive variation in lots.

I am fairly new to reloading too, but i noticed a large variation within the same box of 7mm 175 smk. I was pretty surprised in the inconsistency, but they did shoot well ~ .3"-.5" 5 round groups @ 100 yards
 
#3
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dieselgeek</div><div class="ubbcode-body">Today I was loading up 100 rounds of 178 amax when one box ran out, so I started to grab another box. I measured the first round I loaded and noticed it to be a good amount longer OAL then the last round from the last box. I had 5 set aside from the 1st box so I measured from the Ogive on them and noticed this.

Lot number 211-0064
Ogive..698-700


Lot number 212-0094
Ogive .707-710


Anyone else notice that big of a difference from lot to lot? Forgive me if this is common, I'm fairly new to reloading. </div></div>

It is not that uncommon to see this much variation in bullet base to ogive measurement. Hornady A-MAX bullets are more consistent than Sierra SMKs at least in .308 but you can load a 175g SMK faster due to bullet shape. The A-MAX 168g when loaded right are the equal of a 175g SMK to 1,000 yards and it seems like most stock Remington actions with 24" barrels prefer the 168g A-MAX over the 175g SMKs. Try not to get too tied up in the numbers and working instead based on the way a load works in the field.
 
#4
Re: Bullet ogive variation in lots.

Hmm, never really noticed since I am loading each round measured case head to ogive so I always have the same distance to the lands. This makes the overall length vary but I dont care unless it is pressing the mag length.
 
#5
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KYpatriot</div><div class="ubbcode-body">Hmm, never really noticed since I am loading each round measured case head to ogive so I always have the same distance to the lands. This makes the overall length vary but I dont care unless it is pressing the mag length. </div></div>

Right, that's what I was doing, but when I grabbed a different box, and seated the bullet on the same die, it was longer. So I had to adjust my die to get the same OAL from the ogive.
 
#6
Re: Bullet ogive variation in lots.

Ok, gotcha. I use a micrometer die, and I find that even within the same box I am occasionally adjusting .003 or .004. The variation you are seeing, as much as .012, does seem kind of excessive. I guess as long as you don't have a really compressed load you can compensate for it but it does seem like a lot.
 
#7
Re: Bullet ogive variation in lots.

I've seen as much as .010" difference in base to tip measurements in several lots of 208 amaxes. The base to ogive variation is usually a little bit less but still around .008" or less...

In my limited testing I haven't found a significant difference once an optimal load was properly developed. Will it make a difference? Yes it can. Can you tune a load that will minimize the effects? The answer is also yes.

If you really want to get a handle on it, sort your bullets by base to ogive length.... It's been done and is still done today...I did for a little while to see how significant it was and for my shooting it was not significant enough that I could tell with an optimal load.
 
#8
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KYpatriot</div><div class="ubbcode-body">Ok, gotcha. I use a micrometer die, and I find that even within the same box I am occasionally adjusting .003 or .004. The variation you are seeing, as much as .012, does seem kind of excessive. I guess as long as you don't have a really compressed load you can compensate for it but it does seem like a lot. </div></div>


Same here, I have a Forster CoAx and the Forster Microseater die. The bullets from the same lot, were enough to not worry about. I'll see how these shoot, and then try sorting if it does not seem right.


Thanks

DG.
 
#9
Re: Bullet ogive variation in lots.

The difference is the actual bearing surface length... To really sort it properly you would need two comparators. One to sit on the boat tail and the other on the ogive. That will give you your bearing surface length or at least a better representation of it. That is probably where your variation is coming from... .003-.004" variation I wouldn't even sweat it uses you were shooting benchrest.. Or chasing down a long range record of some sort.... But to each their own.. I've been down that path before... I won't say it doesn't matter, but I'm learning to say."I can get by without that added step..."
smile.gif


Again, not arguing whether or not its worth it, only you can decide that. Can the difference be shot..... Only you can decide that as well ..
 
#10
Re: Bullet ogive variation in lots.

I normally found this problem with 175 SMK.


If you prefer more consistency projectile, I would recommend to go with Berger Bullet.
 
#11
Re: Bullet ogive variation in lots.

Hate to say it... But I've seen the same variation with bergers too...I don't know if its caliber specific though... Some may be better than others but I doubt it....
 
#12
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Frogman77</div><div class="ubbcode-body">The difference is the actual bearing surface length... To really sort it properly you would need two comparators. One to sit on the boat tail and the other on the ogive. That will give you your bearing surface length or at least a better representation of it. That is probably where your variation is coming from... .003-.004" variation I wouldn't even sweat it uses you were shooting benchrest.. Or chasing down a long range record of some sort.... But to each their own.. I've been down that path before... I won't say it doesn't matter, but I'm learning to say."I can get by without that added step..."
smile.gif


Again, not arguing whether or not its worth it, only you can decide that. Can the difference be shot..... Only you can decide that as well ..</div></div>


Thanks, I was just trying to make sure I'm not goofing something. I'm going to keep trying the same OAL and try to buy as many as I can from the same lot.

Def not a bench rest shooter, but everyone likes to see a tight group right!
 
#13
Re: Bullet ogive variation in lots.

dieselgeek,

Yes, perfectly normal, especially depending on how you measure this. If you're measuring the ogive itself, you shouldn't be seeing so much difference, but the OAL of the bullets themselves, or the Loaded OAL of finsihed ammo, this is perfectly normal.

Need to make something very clear here, too; you shouldn't "adjust" to make this all uniform on your finished ammo. Someone mentioned using their micrometer seating die to go back and uniform these, and that's a mistake. In doing so, you're now creating differences in the critical ogive to rifling relationship. The actual OAL will vary by several thou, and doesn't make a bit of difference so long as the tips aren't hanging up on the front of the magazine. Start using a bullet comparator like the Sinclair or the Davidson (my choice) and you'll see exactly what I'm talking about here.
 
#14
Re: Bullet ogive variation in lots.

I had a bigger varience than .010 with Nosler Custom Comp. bullets. So far the closest bullet to seating to the same OAL is the Lapua's. The 139 gr. 6.5s are great. I want to try some 30 cals. BILL
 
#16
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">dieselgeek,

Yes, perfectly normal, especially depending on how you measure this. If you're measuring the ogive itself, you shouldn't be seeing so much difference, but the OAL of the bullets themselves, or the Loaded OAL of finsihed ammo, this is perfectly normal.

Need to make something very clear here, too; you shouldn't "adjust" to make this all uniform on your finished ammo. Someone mentioned using their micrometer seating die to go back and uniform these, and that's a mistake. In doing so, you're now creating differences in the critical ogive to rifling relationship. The actual OAL will vary by several thou, and doesn't make a bit of difference so long as the tips aren't hanging up on the front of the magazine. Start using a bullet comparator like the Sinclair or the Davidson (my choice) and you'll see exactly what I'm talking about here. </div></div>

KT is correct - maybe I wasn't clear - I use a micrometer seating die to make sure all my ammo is uniform when measured using a comparator. You are correct, the overall length to the bullet tip will vary, the length to the ogive will not - obviously this is the purpose of a micrometer seating die.
 
#17
Re: Bullet ogive variation in lots.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KYpatriot</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">dieselgeek,

Yes, perfectly normal, especially depending on how you measure this. If you're measuring the ogive itself, you shouldn't be seeing so much difference, but the OAL of the bullets themselves, or the Loaded OAL of finsihed ammo, this is perfectly normal.

Need to make something very clear here, too; you shouldn't "adjust" to make this all uniform on your finished ammo. Someone mentioned using their micrometer seating die to go back and uniform these, and that's a mistake. In doing so, you're now creating differences in the critical ogive to rifling relationship. The actual OAL will vary by several thou, and doesn't make a bit of difference so long as the tips aren't hanging up on the front of the magazine. Start using a bullet comparator like the Sinclair or the Davidson (my choice) and you'll see exactly what I'm talking about here. </div></div>

KT is correct - maybe I wasn't clear - I use a micrometer seating die to make sure all my ammo is uniform when measured using a comparator. You are correct, the overall length to the bullet tip will vary, the length to the ogive will not - obviously this is the purpose of a micrometer seating die. </div></div>

I agree.... However I've gone back and forth on which is actually more accurate and consistant in regards to keeping the ogive in proper distance from the rifling i.e. measuring the oal using a bullet comparator or just trusting the micrometer die with the appropriate seater stem for that type bullet.... Ive done both and currently I simply set a jump or jam with a test bullet and seat my bullets accordingly without adjusting even if the measurements on coal using a bullet comparator are varying. So far the results are still accurate... Again I still believe a properly developed load will minimize the effects of bullet variations .
 
#20
Re: Bullet ogive variation in lots.


A large part of the velocity variation people see who have good chronographs is due to bullet bearing surface variations and variations in bullet base to ogive. These variations can make significant changes in case volume which affect pressure and velocity. I think the a good way to get into the single digit SD zone is to sort bullets by weight and bearing length. Of course AFAIK it only matters if you are shooting at long range or benchrest.
 
#21
Re: Bullet ogive variation in lots.

One other thing. You can get varying OALs no matter how they are measured with heavily compressed loads (which put a premium on consistent neck tension) or if the bullet "sticks" in the die, for which you need to polish the seater stem.

I had a Forster seater stem that was giving me fits, and putting a shiny ring on the ogive of the bullet. The bullets were actually sticking in the stem a little which was causing variation in COAL, all were coming out longer than they were supposed to be based on the micrometer setting. Looking at the inside of the seater stem any tool marks were basically imperceptible, nevertheless I wrapped some 0000 fine steel wool in the shape of a bullet on a .223 bore brush and chucked it in a hand drill and polished the sucker. Lo and behold it worked, and I can now make adjustments using the micrometer die down to .001
 
#22
Re: Bullet ogive variation in lots.

Thanks for all the info guys. I have a Forster seater as well, I have noticed it will "suck" onto a bullet. I threw it in the ultrasonic cleaner.


It seems pretty rare that the case head to ogive measurement comes out different now. It seems the first one is always the one that does it. I'll just have to keep an eye on it.
 
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