Bullet weight variation and accuracy?

[wolfe28]

What is an acceptable amount of variation in projectile weight when trying to work up the most accurate load for a particular gun?

I am currently working up loads for my 22 Hornet, using winchester brass (new, unfired), winchester small rifle primers, Lil-Gun powder and Hornady 40 Grain v-max projectiles. Max load (per Hogdon's website) is 13 grains of Lil-gun for both 35 and 45 grain projectiles. I started at 11.9 and have worked up in 0.2 grain increments to 12.7 so far. 100 yard rested groups went from about 9 inches with the 11.9 grain charge to about 2.5 with the 12.7 grain charge.

So back to the original question. If I weigh the projectiles I'm using, there is going to be some variation, but what is acceptable, and what isn't? Variation of 1-2 grains in projectile weight for this loading means a variation of 2.5 to 5 percent, which, I'm thinking, will throw off my accuracy and not allow me to get a fairly tight group (I'll be very happy with something under 1 inch at 100 yards). Or, am I letting my scientific analretentiveness get the better of me?

 

[taliv]

i'd have to say i'm extremely skeptical that you'd find a 1-2 grain variation in the weight of any given box of 22 cal hornady bullets.

i grab a handful of my sierra match bullets (69 and 80g) from each new box and weigh them and i can't remember ever having seen even a .1-.2 deviation.

now, that doesn't mean they're necessarily good enough for benchrest, that the jackets are the same weight/thickness, or that they'd pass the spin test. but it's good enough for high power and varmint thwacking

 

[R.W.Dale]

that's why I gave up on buying hornady bullets some time ago. My last box of 168gr "Natonal match" Varied in weight by almost 4 grs from high to low.

The people at Sierra don't call themselves "The Bulletsmiths" without reason.

And then there is the box of spire points that when seating COL varies by as much as .080:banghead:

 

[mc223]

Large variations in projectile weights will have an effect on accuracy. But in 22 Hornet, my findings on accuracy have leaned toward primers. Try different primers with the same powder charge.

 

[JackOfAllTradesMasterAtNone]

+ or - 2% bullet weight is all that I'll allow for rifles. But I don't have anything smaller than .243. For the big pistol bullets with aerodynamics just a touch better than a brick, I'll stretch to +/- 4%

I have been happy with Hornady rifle bullets. Not so with their pistol bullets concerning accuracy.

In my rifles, I can get terrific accuracy with Sierra bullets, but not the velocity I want. I can get near the same accuracy with Speer, and I'm able to push them a bit harder. One of my rifles shoots near match grade with Hornady's at a velocity that's pushing the outer envelope. I'm happy with them.

Finding the right bullet for your rifle may be the challenge. But don't swear off one brand or the other until you've found the one your rifle barrel likes.

Once I've got a rifle load nearing 2" groups at 100yds, no matter the caliber, I work the load .1gn at a time until it's obvious that there's no change in accuracy. Then I experament with bullet seating depth with a charge reduced by .1gn. I also balance the accuracy by the firearm I'm shooting, and the velocity attained. (A chronograph is an invaluable tool for the reloader.)

-Steve