Question on bullet weight consistency

[JayR]

I have just gone through and weighed and sorted about half a box of 139g SST's, they weighed from 138.2 to 141.1g. Does that seem like large spread? When I have weighed barnes and noslers, I thought I remembered less than a grain difference, I was thinking clser to .5 grain. How much would a 2 grain difference affect consistency?

 

[Buffalobob]

You have at least a 1% variation. However the 139 SST is not a long range bullet so it probably is not going to affect much for the ranges you will be shooting.

 

[J E Custom]

I have just gone through and weighed and sorted about half a box of 139g SST's, they weighed from 138.2 to 141.1g. Does that seem like large spread? When I have weighed barnes and noslers, I thought I remembered less than a grain difference, I was thinking clser to .5 grain. How much would a 2 grain difference affect consistency?

At one time or another most all bullets will weigh slightly different from each other so for
precision shooting at long distances weight sorting bullets is a good idea.

If they have more than 1/2 a grain spread I use them for close range or fouling shots.

For 1000 yard matches I sorted enough to make the match with them all weighting the same.

A 3 grain spread is unacceptable as far as I am concerned even for fire forming.

There are better bullets than that and I would discontinue using them and find a better quality
bullet for all shooting.

J E CUSTOM

 

[rscott5028]

I may be all wet. (again) but...

As I see it, a 139g bullet with a .284 dia and a .486 BC must have a SD=0.2462 and a form factor=.5066.

If the form factor remains constant and you vary the weight from 138.2 to 141.1, then the BC would vary from .483 to .493.

If all of those assumptions and calculations were true, then the 138g bullet fired @ 2900 fps will drop ~325" at 1k vs ~320" for the 141g bullet.

Hence, a 5" vertical spread from change in mass alone.

Other factors such as MV and form factor may not remain constant. So, that whole line of reasoning may be flawed.

-- richard

 

[WV Sendero]

I agree with what others have said. Close range it won't matter much but for long range your spread should be closer. I would shoot those up and find a better bullet.