Still learning this cartridge and it's idiosyncrasies so today I did a little investigating and an inconclusive test with these two brands of brass..

Took one piece each and plugged the primer pockets with an upside down primer and then used my new Hodgdon LeveRevolution powder as the media to try and measure case volume.

After five drops and leveling off full cases the Hornady averaged 148.5gr and the Starline avg. was 147.4gr The cases themselves weighed; Hornady 110.7gr., Starline 109.3gr..

So with this short test it looks like the deviation between the two brands is not that great. Being only 0.3gr difference. With the Starline have a slightly larger capacity.

I still haven’t attempted to weight and sort cases. Perhaps if I was competing, but at my age the noise from my body makes it difficult to asses the noise these techniques eliminate.

Only reason I weighed these cases was to determine weight differential between the case capacities. I have been told there is a noticeable difference in capacity between the two brands.

I guess 0.3gr is significant as I as many do use that to increment ladder charges.

(04-29-2024, 11:08 PM)KMW1954 Wrote: [ -> ]Still learning this cartridge and it's idiosyncrasies so today I did a little investigating and an inconclusive test with these two brands of brass..

Took one piece each and plugged the primer pockets with an upside down primer and then used my new Hodgdon LeveRevolution powder as the media to try and measure case volume.

After five drops and leveling off full cases the Hornady averaged 148.5gr and the Starline avg. was 147.4gr The cases themselves weighed; Hornady 110.7gr., Starline 109.3gr..

So with this short test it looks like the deviation between the two brands is not that great. Being only 0.3gr difference. With the Starline have a slightly larger capacity.

So was this new unfired brass? Or once fired brass? Comparing the capacity of new brass is kind of pointless as the shoulder could be +/- .010 or more and the OAL can be =/- .005 or more. It needs to be "uniformed" to a chamber and then trimmed to the same OAL and chamfered the same to get a useful comparison between brands.  Im not sure I understand your last sentence, "So with this short test it looks like the deviation between the two brands is not that great. Being only 0.3gr difference. With the Starline have a slightly larger capacity"
 The common capacity measure I'm familiar with, (as it is what Quickload uses),is overflow grains of water in once fired brass with the fired primer still in place. To do this accurately you fill a case with water using an eye dropper until the last drop makes it overflow, then look at the meniscus and match that meniscus when filling the cases on the scale.

Both cases are once fired and resized. A fired primer was then seated inverted to use as a plug. Was then filled with powder to overflow and then leveled off. So in this case the metric is grains of powder weight rather than using a fluid capacity.

I have tried doing fluid measure and just wasn't comfortable with the results.

Last sentence, "Starline has a slightly larger capacity." That being the Starline had a powder weight .3gr consistently greater than the Hornady brass of the same powder..

Interesting, thanks for doing this. It's a good starting point. Sounds like, in my terms, powder capacity of the starline is 0.3 grs bigger, which about the 1% charge delta for this cartridge case. Lever is pretty fine so that's a good reference to start with. Doesn't mean that each case will be ~30 fps different, have to see now what an equal powder charge in hdy and starline (1x of course) means for a typical bullet. I would figure that the ST then would be a slower MV but it should be checked to see.

Right now I'm using all Hdy 6Arc (but Starline in 6.5 Gr) but have some starline, just seems so far that the hdy is doing ok for me... or else I'm not noticing an issue. Consistency in case size is the most important thing. Biggest changes I've been handling so far is to fcd the AR rounds and use the fed 205M's for the bolt action (cci450 in AR). Those things are helping. I think!

In some Hdy 6.5 CM brass I have, I noticed that one batch (maybe from blank cartridges) weighs more than another bunch I have (I think these came from factory loads). Blank cartridges were 150-152 grs with some small outliers, and factory load cartridges were 144-145 grs with outliers. I set the 140-class brass aside and a couple test rounds with just the 152's seemed much more consistent (MV) for some 120 loads I'm looking at.

This 6Arc Hdy however, I don't notice a delta. But I could be missing it.
So the starline is just waiting on the shelf for its turn.

Thanks grayfox. I believe I am going to repeat this little test only this time using AA2460 as it is a very fine ball powder that is very consistent in size and actually jambs up my powder trickler. While I am at it I may also compare a 6BR Lapua case I have sitting on the bench.

Ive noticed the extra capacity with the starline brass as well. The starline seems to be a slightly harder alloy also. At this point the starline brass might be slightly better in terms of durability and capacity.