Variations in bullet diameter?

[MarinePMI]

Has anyone run into this before? (Variation in bullet diameter)

I was just loading some Sierra 77gr TMK, and noticed when using my Wilson seater die, that most bullets slowly went down the hole due to air displacement.

However, I had 2 that literally dropped down the hole like a rock, and a handful rubbed on the walls of the hole and had to be physically pushed down to the case mouth. This seems to indicate to me a variation in diameter from the swaging and pointing process/plastic tip seating.

I don't weigh cases, and occasionally check ogive location when I see weird fliers (blems show this pretty often), but never thought, or really noticed, a variation in diameter until now.

So, I was just curious if others have seen this as well?

 

[Dogtown]

I've seen variations like this from bulk pulled bullets in the past.

Bullet variation from new bullets is almost exclusively found at the meplat and overall mass, not so much in the diameter. Quality control will usually catch major outliers.

 

[918v]

You’re not supposed to be dropping the bullets into the hole like that. You will wear out the seater bore.

I don’t think it’s a variance in bullet diameter but rather a variance in bullet roundness. A lot of these bullet boxes are kicked around and dropped during shipping and all that weight beats the bullets and squished them. You end up with oblong bullets. They still shoot well because they swell under pressure and fill the throat and get squished down again by the rifling .

 

[straightshooter1]

Has anyone run into this before? (Variation in bullet diameter)

I was just loading some Sierra 77gr TMK, and noticed when using my Wilson seater die, that most bullets slowly went down the hole due to air displacement.

However, I had 2 that literally dropped down the hole like a rock, and a handful rubbed on the walls of the hole and had to be physically pushed down to the case mouth. This seems to indicate to me a variation in diameter from the swaying and pointing process/plastic tip seating.

It's not clear as to what's going on there. What "hole" are you referring to . . . the case neck?

Are you saying you dropped these bullets down the very same hole (same case neck) or were there other cases you were dropping them down in?

I don't weigh cases, and occasionally check ogive location when I see weird fliers (blems show this pretty often), but never thought, or really noticed, a variation in diameter until now.

So, I was just curious if others have seen this as well?

I have not experienced this. For bullets to drop down through a particular case and others not could certainly suggest bullet's with different diameters. And that would be quite a significant difference. But, I have had this happen where bullets would drop down some cases and not other cases as there can certainly be differences in inside case neck diameters . . . especially if one is not turning necks.

 

[918v]

I think he removed the seater stem from the die body and was dropping the bullets into the hole, then sticking the seater stem on top and seating the bullets.

 

[bakerp30]

Go straight to your brass and check the difference in your neck tension, are you using different brand of brass ?? .... sounds like you were having a sizing issue and not a bullet issue.....
Are your bullets measuring a different diameter??

 

[straightshooter1]

I think he removed the seater stem from the die body and was dropping the bullets into the hole, then sticking the seater stem on top and seating the bullets.

OH, I think you're right. I've never actually used my Wilson seater die that way.

So, because bullets have very good tolerances for diameter, his issue suggests to me it might have something to do with either some variance in the way the case fits or maybe a small flaw on the surface of the bullet ( a dent or scratch???) allowing air to pass by easy where they will just drop through rather than slowly when air doesn't have a way to pass so easily.

 

[Supersubes]

Go straight to your brass and check the difference in your neck tension, are you using different brand of brass ?? .... sounds like you were having a sizing issue and not a bullet issue.....
Are your bullets measuring a different diameter??

The hole he’s talking about is in his wilson in-line seater die.

 

[Steel head]

Go straight to your brass and check the difference in your neck tension, are you using different brand of brass ?? .... sounds like you were having a sizing issue and not a bullet issue.....
Are your bullets measuring a different diameter??

I think yo need to Re read the OP’s post.

 

[MarinePMI]

RIF....

 

[MarinePMI]

 

[Milo 2.5]

Did you measure any bullets for a diameter change? Not the tool for the job, but a decent caliper will give you an idea. I am with an above poster, these tolerances are pretty tight.
For comparison, you can buy 6mm barrels in either .236 or .237" bore, I have heard that getting a .0008" between any of them would be rare, I have no way of measuring this myself, just trust the word of a prominent smith.
A .0005" change in bullet dia would be friggin huge and may cause issues in the grand scheme, not blow your gun up BS, but you will notice firing it, generate considerably more or less pressure.