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Topic: Which brass: Lapua, Peterson , or Starline? (Read 2118 times) previous topic - next topic

Re: Which brass: Lapua, Peterson , or Starline?

Reply #15
ALL THE WAY,
I know you have chose the small primer.  But I thought I would share my findings up to date with Starline large primer.  Have only gone thru part of the lot but so far weights & volumes have been close only requiring 3 subcategories for "my" preference of plus or minus 1/2 grain of H20 (approximately 1 1/2 grs case weight).  Only 13 culls out of 100 (better than the Federal I bought).

The thing I didn't like about the Starline LP is that my RCBS uniformer did not reach the bottom of the pocket as new and even on the once fired I see only the outside perimeter is just barely touched.  That carbide cutter seems to last forever and is the best primer pocket "cleaner" out there.
I don't read much about who or who doesn't read their primer pockets but I use the uniformer every loading.  Usually the pocket requires two or three "cuttings" before it starts to travel forward.  It maintains that condition for many firings and throughout the useful life of the case.  If ever the pocket requires additional "cutting" something usually is array like incipient head seperation or an overpressure load condition existed.
Hopefully I will see a smidge more of a "cut" on firing number three.
Good Luck with the Starline,
Randy
11X Grandfather
Part time Savagesmith

Re: Which brass: Lapua, Peterson , or Starline?

Reply #16
Randy - with regards to h2o capacity testing and case weighing.

Do you find good correlation between case weight being "heavy" and H20 volume decrease?

 If you've got data on 100 cases (or any type) where you have both the h20 volume and case weight recorded, i'd love to play with that raw data to see how tight this correlation actually is.

can you say more on when you're chosing to cull based on 1.5grs case weight variance.  with hornady and winchester, the ES of case weights  was 3.2gr  which means even the lightest cases were only 1.6gr lighter than average and heaviest only 1.6 heaver than avg.  not far outside your tolerance if i'm reading it right.

Re: Which brass: Lapua, Peterson , or Starline?

Reply #17
Randy - with regards to h2o capacity testing and case weighing.

Do you find good correlation between case weight being "heavy" and H20 volume decrease?

 If you've got data on 100 cases (or any type) where you have both the h20 volume and case weight recorded, i'd love to play with that raw data to see how tight this correlation actually is.

can you say more on when you're chosing to cull based on 1.5grs case weight variance.  with hornady and winchester, the ES of case weights  was 3.2gr  which means even the lightest cases were only 1.6gr lighter than average and heaviest only 1.6 heaver than avg.  not far outside your tolerance if i'm reading it right.
denellans,
Sorry I should have said plus or minus 1 1/2 grains.  And yes your p/m 1.6 is close to my 1.5.  A lot that close is a good one I would mark and shoot even the culls because they might just be fine as is.  Nosler weight sorts their high buck brass usually p/m 1 gr or so.  But I weigh them all anyway and etch the weight on the case.  Weight sorting and volume most times correlate but not always.  Thats why I do them both depending on the rifle they are intended for and if I am trying to figure out a problem.  Volume alone sometimes doesn't explain a problem within the cartridge/case and "shoot" sorting is the only way to cull them out.  I have seen the heaviest case in a lot have more volume than the lightest if that explains anything except that the internal shape may be way different.
I am "old" but still learning this stuff.  Been loading for 50 years but trying to make my hunting rifles better I keep experimenting and testing.
Later,
Randy
11X Grandfather
Part time Savagesmith

 

Re: Which brass: Lapua, Peterson , or Starline?

Reply #18
9 grains is a lot - what are/were you seeomg for absolute weight on those? i weighed a bunch of hornady and winchester which were 151.1gr and 155.5 gr respectively (avg)

I don't remember exact weights, but Prime was heavier than Hornady, Lapua heavier than Prime, and Peterson heavier than Lapua. I only have Peterson, Prime, and Hornady on hand right now. Once I get my A&D scale set up, I will weigh those and report back. I sold my Chargemaster today and ordered the Auto Trickler to go with the new scale.

Re: Which brass: Lapua, Peterson , or Starline?

Reply #19
Prime brass is made by Norma IIRC.
RPR 6.5 Creedmoor
Bergara 6 Creedmoor

Re: Which brass: Lapua, Peterson , or Starline?

Reply #20
Anybody using alpha brass ? There 308 brass is very consistent but have not tried 65 yet

Re: Which brass: Lapua, Peterson , or Starline?

Reply #21
so i re-did my weight experiment for hornady, win, and starline 6mm creed. 50 cases each. the hornady had an ES if 6.2 gr this time which over the 149.3 gr average is ~4.5% variance. 

compare that to something like powder charge of .1 gr variance over 43gr, which is ~0.2% variance.

i’m not much of a metallurgist, but since all brass was resized and trimmed to length just before weighing. if external dimensions are identical... either the interior volume is indeed smaller on some cases or the density of the brass is different (or both).

i shoot enough that many different hornady cases continually mix through my process in the washer mainly. i might have to start doing some brass weight sorting, 4.5% variance seems way out of line to me. winchester extreme variance was just 3.4 and starline was 2.9.

even just grouping into 4 groups per 100 would drastically improve the extreme variance in any given sub group... might even show up on target, who knows


Re: Which brass: Lapua, Peterson , or Starline?

Reply #22
I did an unscientific test of Alpha 6 creed brass.  Length and weights were very consistent.  Equal or better than Lapua.  One thing though, the primer pockets ( large ) had to be squared up some.  Never had to do that with Lapua brass.

Re: Which brass: Lapua, Peterson , or Starline?

Reply #23
Interestingly I notice Peterson brass is now sold through Grafs & Sons rather than direct.  I’m guessing they were getting enough orders it was beneficial to find someone to handle the retail end of things. 

Re: Which brass: Lapua, Peterson , or Starline?

Reply #24
so i re-did my weight experiment for hornady, win, and starline 6mm creed. 50 cases each. the hornady had an ES if 6.2 gr this time which over the 149.3 gr average is ~4.5% variance. 

compare that to something like powder charge of .1 gr variance over 43gr, which is ~0.2% variance.

i’m not much of a metallurgist, but since all brass was resized and trimmed to length just before weighing. if external dimensions are identical... either the interior volume is indeed smaller on some cases or the density of the brass is different (or both).

i shoot enough that many different hornady cases continually mix through my process in the washer mainly. i might have to start doing some brass weight sorting, 4.5% variance seems way out of line to me. winchester extreme variance was just 3.4 and starline was 2.9.

even just grouping into 4 groups per 100 would drastically improve the extreme variance in any given sub group... might even show up on target, who knows


My original thought too was weight should be directly proportional to volume when the outside case dimension was the same.
I measured a few case externally and found things like variations in extraction groove diameters, rim thickness and case wall variations.  I cut two non-complient samples lengthways with a hacksaw and measured the thickness at the flash hole which was different. 
Though not very scientific, it explained to me that the correlation can be swayed by several different factors.
It also told me that internal shape can be slightly different from case to case but still have the same volume.  That is where my conclusion was made that case/weight volume may be perfect but some cases possibly shoot different because  of internal shape.  But I'm not smart enough or good enough to prove it.
Thats why unless a case is totally unacceptable, every case gets a chance to prove itself at the range. And a few "heavies" have found themselves marked with a sharpie as a cold barrel round for hunting.  Same charge, probably a little less volume, but same point of impact as round 2 & 3 with nearly same MV.
Nuff said going outside to shoot.
Later,
Randy
11X Grandfather
Part time Savagesmith

Re: Which brass: Lapua, Peterson , or Starline?

Reply #25
Interestingly I notice Peterson brass is now sold through Grafs & Sons rather than direct.  I’m guessing they were getting enough orders it was beneficial to find someone to handle the retail end of things. 

I bought my first 200 from Peterson direct and another 200 from Grafs. It was cheaper from Grafs.