Brass length consistency

[Mike D Texas]

I recently purchased some Peterson 260 Remington small rifle primer brass to try out.

When going through last night sorting to get ready to trim, I found a huge swing between the shortest and longest piece of brass.

In the picture the shortest measured 2.022" (left) and the longest measures 2.031" (right).

For kicks I grabbed 10 random pieces of Lapua out of a new box and they all measured within .005" of one another.

I though Peterson was supposed to be considered a premium brass?

All are within SAAMI minimum length but I was a bit disappointed in the large variance.

 

[Jud96]

I've never had that problem with Peterson brass. I wouldn't worry about it. Trimming brass isn't that big of a deal to me though

 

[Mike D Texas]

I agree I always size and trim new brass as part of my prep but I was just surprised at the inconsistency.

 

[fguffey]

I've never had that problem with Peterson brass. I wouldn't worry about it. Trimming brass isn't that big of a deal to me though

If case length was critical I would have a forming die for ever chamber. Raise the ram, run the man tool across the top of the trim die, bevel etc.

I would be be interested in the difference in length of the cases from the shoulder/datum to the case head. And then there is the weight and case head thickness.

F. Guffey

 

[Mike D Texas]

So given my scenario above, should I:

1. Trim all brass to the shortest length for uniformity?
2. Trim all brass to the middle length?
3. Don't trim at all until after measuring after first firing?
4. Nothing until it stretches to SAAMI max length? (The rifle has a factory chamber).

 

[fguffey]

So given my scenario above, should I:

All I can do when matching the case length is to trim all cases to the length of the shortest case. It seems the length is critical when the difference in length is a few .005"+/-. When I form cases I expect most of them to shorten .035". And then there is case neck length; I have a 30 Gibbs with a .217" length neck and a 300 Win Mag with a case neck length that is .270"+/-.

And then there is the RCBS-X die. RCBS recommends the case be shortened .020" before the reloaders starts. And then there is the suggestion that shortening the case .020" will eliminated trimming. I do not agree but when the case neck increases .020" it would be time to start over with new cases.

F. Guffey

 

[elf]

Virgin brass will shrink some after initial firing. Then, I trim all cases to within .005"

 

[fguffey]

Virgin brass will shrink some after initial firing. Then, I trim all cases to within .005"

If brass shrinks after firing or after sizing or when I am not watching it there is nothing I can do about it. I have never spent more than a few seconds thinking about it. I have trouble convincing reloaders they should measure before and again after; like before firing and again after firing and before sizing and again after sizing. If brass pops back and in doing so made a sound there is a remote chance I would be curious.

And then one day I read on a reloading forum that brass, after sizing recovers length, diameter etc. etc. for 5 days. And then I had one of those moments when I reflected back to my Ol Grandpa, he did not get excited about anything, one day he told me he would not walk across a street to watch an ant eat a bail of hay; and we had a good laugh.

F. Guffey