Bullet weight variance and accuracy

[chas442]

I would like to hear from anyone that may have determined how much of an influence a small variation in bullet weight affects accuracy.
I just finished sorting by weight 500 SMK 30 cal in 175 gr.
I did not count how many were actually in aech weight group but this is what I found.
1/3 of total were 174.9 gr
1/3 of total were 175.0 gr
about 1/6 of total were 175.1 gr
about 1/6 of total were 175.2 gr
a handful were 174.8 and 175.3
Some may think that I am just wasting my time. I only shoot 100 yards at this time and all these may be adequate for reasonable accuracy.
I have annealed, sorted brass by brand, weight, and dry capacity as well as sizing to the same dimension and trimming to the same length.
My shooting at 100 yards is just a starting point if I can get a real accurate load and I can do my part.
I have access to 200 and 300 yd ranges.
I am trying to take all variables out of the equation so that I can see the results of my own shooting ability.
Does 0.1 or 0.2 gr variance in a projectile that weighs 175 grains really make a difference at the distances I shoot? At what distance does it make a difference?
I usually group 1 inch at 100 yards from a Rock River LAR 8 with a 26" bull barrel.

 

[jmorris]

How you weigh them might be as large of a factor as anything.

By any chance did you take one bullet, maybe marked with a marker and weight it as #1, 50, 100, 150, etc. using it as a “standard”? If it was always the same weight, then I would trust your results.

Might be pretty hard to tell anything as close as 100 yards even if they were off by that much.

Maybe get a decent rest, so it actually takes you out as a variable and see how your load does, then reintroduce yourself and see if you can beat the “machine”.

 

[chas442]

I was using an RCBS powder pro digital scale. I have evry confidence in the scale. I did not have 1 bullet as a base line. I did periodically check a bullet out of each grouping to verify accuracy. I believe the scale has a +0.1 or -0.1 accuracy rating. I did find that a bullet weighed earlier was the same weight later in the weighing episodes. I did a calibration at every start of a every weighing session. Could not do 500 in one sitting.
I do plan on using a lead sled for load developement.

 

[jmorris]

Looks like you are well on you way of eliminating variables. Be sure to post your results.

 

[chas442]

Will do jmorris. It will be a while. A little too cold for an old wimp like me.

 

[jmorris]

I understand it only got to 64 here today

 

[quest4perfection]

I would like to hear from anyone that may have determined how much of an influence a small variation in bullet weight affects accuracy.
I just finished sorting by weight 500 SMK 30 cal in 175 gr.
I did not count how many were actually in aech weight group but this is what I found.
1/3 of total were 174.9 gr
1/3 of total were 175.0 gr
about 1/6 of total were 175.1 gr
about 1/6 of total were 175.2 gr
a handful were 174.8 and 175.3
Some may think that I am just wasting my time. I only shoot 100 yards at this time and all these may be adequate for reasonable accuracy.
I have annealed, sorted brass by brand, weight, and dry capacity as well as sizing to the same dimension and trimming to the same length.
My shooting at 100 yards is just a starting point if I can get a real accurate load and I can do my part.
I have access to 200 and 300 yd ranges.
I am trying to take all variables out of the equation so that I can see the results of my own shooting ability.
Does 0.1 or 0.2 gr variance in a projectile that weighs 175 grains really make a difference at the distances I shoot? At what distance does it make a difference?
I usually group 1 inch at 100 yards from a Rock River LAR 8 with a 26" bull barrel.

That's pretty typical with that bullet. If shooting for ultimate accuracy I would select with top half of average.

 

[chas442]

This the best group out of 10 groups of 5. Finally got a chance to get to the range. I was unable to use a lead sled. I have been waiting for the weather to break and it finally did.
Temps were in the high 50s.
All brass were prepped the same and dry volume checked. All projectiles used were 175.0 gr. SMK
Each powder charge was at exactly the same in each grouping.
This was shot thru a Rock River Arms LAR 24 in. varmenter.

 

[Walkalong]

The question isn't will it make a difference, the question is can you shoot the difference and how far out would it take to show up for us mere mortals.

 

[Slamfire]

The military 174 FMJBT varies plus or minus two grains.

The bullet shot well at 100 yards.



I do not have any 300 yard or 600 yard targets in my account, but even with this weight variance, these bullets will hold the ten ring out to 600 yards.

These are targets in which these bullets were used:

 

[Dwb1957]

A constristity gage is something that really helped my groups out.

 

[30Cal]

I know the answer, but if you want to see for yourself, take your outliers, load them up and shoot them all into one group.

Personally, I wouldn't weigh any box of match bullets with a major label on it.