Bullet weight tolerances

[OR-E-Gun Bill]

Is there some type of standard weight tolerance allowance that modern bullet makers have to adhere to? Say for instance, if you buy a box of 100 Hornady .243 caliber, 87 gr. V-Max bullets, what should you expect the weight of each bullet be? Within 0.2 gr. of 87 gr., plus or minus? What is considered acceptable?

 EDIT:
Searching various bullet manufacturing websites, a few the give their bullet weight tolerances:

BERGER:
Our bullet weight tolerances are listed below. The actual results are usually tighter than these tolerances allow:
........20 gr to 60 gr -- +or- 0.05 gr
....... 62 gr to 115 gr -- +or- 0.1 gr
....... 120 gr to 168 gr -- +or- 0.15 gr
........175 gr to 210 gr -- +or- 0.2 gr

Sierra:
Bullet Weight Control of +/- 0.3 grain



Bill

[tacklebury]

I am unsure if there is any standard industry wide, but I have found very good tolerances on Hornady projectiles in the +/- 0.1 gr average.  I have found more deviance on cast bullets typically and when loading these I weigh and catalog them into groups with +/- 0.1gr increments.  Then I put them into bags grouped with similar weight and load them in sets.  When I just want to make some plinker ammo, I will often use the left over random weights for this or wait till my next purchase and add them to the next weigh-in again.

[Grumulkin]

The tiny bit of weight difference listed is going to make VERY little difference down range.  Of much more importance in accuracy is even weight distribution across the diameter of the bullet; i.e., the bullet must be in balance.

[LanceR]

The tiny bit of weight difference listed is going to make VERY little difference down range. 

Correct. 

Years ago, before ballistic calculators were available, I shot a lot of 800-1000 yards competitions with .308 155 grain and 180-190 grain Sierra MatchKings and Lapua 185 grain bullets out of .308 Win. and .30-.338 Win. Mag rifles.  I used to spend a few long winter evenings weighing all the bullets for a season (4500-5000 of them) and segregating them by weight.   I did the same thing with my 600 yard 168s for service rifle competition.

Out of curiosity I ran the data for the drop and 10 MPH windage for a 0.3 grain weight change for a 180 grain Sierra MatchKing at 2600 FPS and the change in both is under 0.1" at 1000 yards.  In fact as I increased the weight to 3 full grains it finally changed the windage by 0.1" but the elevation drop remained the same.

I figure that the single biggest factor in effecting long range range accuracy of ammo is how consistent you can keep the velocity.  Even very consistent ammo will regularly exhibit a 20 FPS or higher velocity spread so I kept the weight the same and changed the velocity by 20 FPS.

180 grain Sierra MatchKing @ 2600 FPS elevation drop is -457.1", windage is 110.5".

180 grain Sierra MatchKing @ 2580 FPS elevation drop is -465.0", windage is 111.7".

Clearly the velocity spread of even good ammo has far more effect than 'standard" bullet weight differences.

With the availability of ballistic calculators I have found that worrying about the point of impact differences in weight groupings of good target bullets is kind of like pole vaulting over mouse turds.  You can do it if you want but it won't work better.

Drop dead consistency in case prep, neck tension and the weighing of powder would seem to be far more useful places to spend your energies.

BTW, I suspect the that the "industry standard" is what each manufacturer thinks customers expect from a given line and style of bullet.  Match and other fussy shooters expect better consistency than plinkers and are willing to pay for it.  So, I guess the standard is "good enough to get a repeat sale"

Lance

[tacklebury]

Good info.  A lot of the "guides" on getting into BPCR were suggesting grouping bullet weights, so it's a habit I got into. 

[LanceR]

"BPCR"?

Lance

[JustaShooter]

Out of curiosity I ran the data for the drop and 10 MPH windage for a 0.3 grain weight change for a 180 grain Sierra MatchKing at 2600 FPS and the change in both is under 0.1" at 1000 yards.  In fact as I increased the weight to 3 full grains it finally changed the windage by 0.1" but the elevation drop remained the same.

Makes sense - objects fall at the same rate regardless of mass / weight (remember Galileo dropping the different weight balls from the leaning tower of Pisa?).  The elevation drop is all about time of flight - as soon as the bullet leaves the barrel it starts to fall, and how far it falls before it hits the target depends on how long it took to get there, which is all about velocity.  So if the bullets leave the barrel at the same velocity, time of flight is the same and so is drop, regardless of weight.

Now, the same powder charge will launch bullets of different weight at different velocities, but the difference isn't going to be measurable - natural variations in other factors (like the primer and powder burn rate) is going to swamp the velocity difference.

Just a Shooter (and physics guy)

[tacklebury]

"BPCR"?

Lance

Black powder cartridge

[bobg]

  The biggest weight difference i have seen was with Speer 22 caliber 50 grain bullets. They varied 3 grains.
   Probably didn't make any difference but it did to me. Haven't shoot another Speer bullet in years.

[temmi]

I’m one of those geeks who weigh and sort all of my bullets.

For the standard Speer, Hornady and Nosler .338 Cal 200g bullet the weight variation is +/-.4, with the occasional outlier which could be up to 1g.

The same is true for Speer, Hornady and Nosler .308 150g bullets.

For Speer .458cal 400g flatpoint & Horn 350g bullets… the variation is a full +/- 2g… So much that I use .5 grain lots.

Much the same is true for the all Lead .452 200g and 250g bullets I have tries +/- 1.5g

Oddly enough the Speer & Horn .475 325g bullets are a tad better with +/- 1g


That help?