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Discussion Starter · #1 ·
Well, obviously a .38 spl will be shorter than a .357 Mag.

Do the small variations in case length affect OAL within the same caliber?

I measured a batch of reloads and found a range of 0.008". I measured the bullets and found a variation of only 0.002". Then I measured some empty cases and found a variation of 0.008".

It doesn't make sense to me though since the bullet seater should set the bullet regardless of case length. I'm using a factory crimp die so the seating die isn't set to crimp - at least I THINK I have it backed out far enough.
 

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What "might" be happening is something a bit different. If the bullet seater is indexing on a specific diameter on the ogive of the bullet as opposed to the nose of the bullet you will find variations of that much or more in both lead and jacketed bullets. Especially with jacketed bullets you will find the OAL varying a good bit from this even with bullets from the same box.

GB
 

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Discussion Starter · #3 ·
Huh?

I'm thinking real hard on this one. See if I understand you right.

The seater indexing on the ogive of the bullet . . . Ok, so I'm loading with RNFP. What you are saying is that the seater may be shaped to fit a RN? This would cause the seater to contact the bullet somewhere around the perimeter of the ogive, instead of right at the center/tip/nose?

It still doesn't make sense to me that once the die is adjusted, it will crank out varying OAL even with the same bullet and same type of cases.

Bottom line that I gather is 0.008" isn't enough to get concerned with unless it causes feed problems.
 

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I may not quite have what he is saying but if it's hitting somewhere besides dead on the flat nose, various deformations of the bullet could cause the differences because it has a different point of contact on each different bullet. Something like that, maybe.
 

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That is correct. Unless the seater is indexing or hitting the nose of the bullet only then it is coming in contact with some point along the curvature of the bullet at a specific diameter. The placement of this diameter is going to vary from bullet to bullet by some small amount. Usually less than 0.010" but not always even in the same box of bullets whether cast lead, swaged lead or jacketed. All will vary some in the nose shape.

You can buy a seater or make it yourself for use with full wadcutter bullets which will then seat or index off the flat on the nose of the bullet. This will minimize the variation from round to round but it is possible nothing will totally remove it.

You are correct that for CAS and for most uses this small difference will have no measureable effect on accuracy.

GB
 
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