Much written on the topic, a lot of it noise, some by folks who actually tested. I have the norma brass 8x firings, JGS reamer, Harrels 4d to size, 105 hybrids, RL16, ~ 3,095-3,100. There is a thread on my testing. My reamer specs were based on Donovan's evaluation and tests, which included "seasoning" brass at least once prior to max loads.
Here are some comments by Donovan back then (I copied and pasted some as the threads are very long):
4 major aspects: (my own input, suggestions, and opinions)
1st <> Case Capacity variation:
The "case capacity" of the Norma Dasher will be less then most users current Lapua made Dashers. With first looks at capacities yielding 0.7 to 1.0-grains less capacity with the Norma Dasher then most Lapua made Dasher's.
Bare this in mind when planning powder charges to be used, and when comparing velocity and pressure to the Lapua made Dasher cases.
2nd <> Case OAL and Neck Length:
The new Norma Dasher cases are some +0.040" longer in neck length. While this is a plus to many scenario's it needs to be kept in mind and addressed to many aspects. For proper fit to the chamber primarily but also to capacity measurements, die fits, neck trimming, neck tension, neck turning, etc., etc...
3rd <> Rim Thickness:
The case head rim of the extractor groove is some +0.010" thicker then Lapua 6BR and Norma 6BR brass.
The added thickness will aid to integrity of the case head and primer pocket. But it comes with a price, and that is many of the commonly used shell-holders may not work with the new Norma Dasher cases and some of rifles actions may have issues that will have to be addressed to extract the fired cases properly.
4th <> Base/webbing diameter:
The base/webbing diameter of the new cases are smaller then many using Lapua made Dasher cases. While they are only 0.001 to 0.0015" smaller, this can be a lot in terms of "case stretch" to the base/webbing area of cases when fired. Any extra stretch in that area will effect case head integrity including the primer pockets and flash-hole. I strongly suggest to bare this in mind when spec'ing new chambers and dies to be used with this new Norma Dasher brass. Tighter specifications in this area will compliment the new brass' integrity.
Donovan
Couple more points I will make, that are of my own opinion and experience:
1 - the base/web diameters of the new Norma Dasher brass are very equal to there existing Norma 6BR brass, and are just slightly larger then any Norma 6BR cases that I have measured.
For that reason I can understand and respect why they may have made the new Norma Dasher brass closer to it in base/web specifications then the Lapua 6BR specs.
2 - based from my own experience, I do not believe the new Norma Dasher brass will compliment larger chambers and/or resizing dies very well (but the jury is still out on this aspect).
I have found over the years and no matter what brand of case, the closer the case can be resized back to factory specs in the base/web area will compliment integrity, longevity, and accuracy potential.
For example; my current 6Dasher brass I fire-form from Lapua 6BR's that measure 0.4685 to .469" on the web/base when new. My current F/L sizing die (a custom) resizes the Lapua made Dasher cases back down to .4688 to .469" at the base/web every time. From which if I don't over pressure the brass I get fantastic brass life and prolonged accuracy potential from them (have some with +60 firings).
At the same time, I have seen Lapua made Dasher cases that were resized with larger spec'ed F/L dies that gave up to best accuracy potential and/or pocket life much sooner, early on in the cycle counts.
With this all said, is why I recommend to keep base/web diameters in mind when spec'ing new chambers and dies for this new Norma Dasher brass.
3 - while "thicker rims" may be a hindrance to shell-holder selection and to some action's fit, I myself perceive the increase in rim-thickness as a positive to case head integrity. Simply because "the more meat, the more strength" sort to speak. The jury is still out on this aspect as well, but I will gear up for the change and look at it as a positive, since if I can get even 1 more cycle of case life from the increase in rim thickness, the cost of few fairly inexpensive shell-holders would be a wash.
Donovan
My 2-cents on annealing Shiraz/Norma cases:
Have 6-firings on some Shiraz/Norma cases, that is to my experience are softer then the Lapua made Dasher's with equal firings considerably. I guess if you plan to anneal every cycle regardless then maybe its the thing to do, but myself I haven't seen or felt the need to yet at all from them.
I also made up Dasher's from both Lapua & Norma 6BR brass to run equal comparisons to the Shiraz/Norma's. The necks on both the Norma and Shiraz/Norma are staying equal as best I can judge them. The pockets on the Shiraz/Norma's have stayed a little tighter then the Norma-BR, and are running fairly equal to the Lapua's so far.
Donovan
Rich -
What I have seen is they start out slower and then they catch up pretty close. Takes a couple firings to get them to adhere and stretch to full capacity potential. There different and they react different.
Edited in later: No doubt do to the metallurgy indifference, they adhere/stretch differently. After the 1st-firing the average capacity on my Shiraz/Norma's was 40.62, verses Lapua at 41.54, verses NormaBR at 40.68.
Then after the 4th-firing they averaged 41.12 compared to the Lapua at 41.68, and NormaBR at 41.16.
** (all capacities measured with H380 <> averages from 3 cases of each)
Both the Norma and Shiraz/Norma remain softer on a whole, that continue to adhere/stretch for a couple firings before settling in, or so has been my experience.
Yes... see you next month !.!.!
Donovan
George
The comparison cases I went easy on the first fire-forming cycle with only 29.7 of RL15 w/ 105-VLD's.
On there 2nd firing loaded them with 32.14 of RL15 / 3015-fps
On there 3rd cycle loaded them with 32.74 of RL15 / 3052-fps
Those were in a 31" Benchmark barrel. The 6th firing was with a 31" Bartlien that averaged 30-fps slower, but is typical of the two barrels (one is faster then the other).
Good Luck
Donovan
CaptainMal -
I hit a few brand new Shiraz/Norma with full charges equal to formed Lapua's upper node loads (+3000-fps). In my opinion, that was to much and the Shiraz/Norma's need to be fire-formed there first time with a mild charge. And even for the 2nd firing should not be a upper node load yet - IME
Made 3 sets to comparison test with. A set from Shiraz/Norma, a set from Lapua6BR, and a set from Norma6BR. Started them all by fire-forming them with the same charge (27.7<>RL15), and shooting them with the same identical loads to each cycle there after, progressively hotter. No doubt do to the metallurgy indifference, they adhere/stretch differently. After the 1st-firing the average capacity on the Shiraz/Norma's was 40.62, verses Lapua at 41.54, verses NormaBR at 40.68. After the 4th-firing they averaged 41.12 compared to the Lapua at 41.68, and NormaBR at 41.16.
** (all capacities measured with H380 <> averages from 3 cases of each)
Both the Norma and Shiraz/Norma remain softer on a whole, that continue to adhere/stretch for a couple firings before settling in, in comparison to the Lapua's.
From these volume variances and the base/web variances occurring, until they settle in it is to my own opinion and how I myself will pursue with them, the charges should be varied as well, linearly to the volumes indifference, until they have settled in.
In closing, there different and act different and react different then Lapua made 6Dasher's, which stands to good reason. What happens with and works in Lapua made 6Dasher's should not be expected to be the same with Shiraz/Norma's. Charge levels, velocity potential, base/web expansion, neck tension, etc., should not be looked as direct cross over to or from the Lapua made Dasher's -- IME&O
Donovan
A little more input from me:
No cases, of any brand, or any caliber should be hit with full bore, upper node loads when there new if one desires consistent volumes, consistent wall stretch, and case longevity - IME
The Shiraz/Norma have appeared to me in cycle stretch specifications and volume growth to act and react very similar to the Norma6BR mother-case made 6Dasher's, but with 2 big advantages: 1) stronger primer pockets, 2) longer neck advantages.
The Shiraz/Norma have appeared to me to have great accuracy potential, velocity potential, and primer-pockets in comparison to Lapua6BR mother-case made 6Dasher's, but need to be prepped and loaded to there own set of demands, which are different demands then the Lapua6BR made.
Donovan
