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  #41  
Old 01-12-2014, 06:18 AM
Tilleyman Tilleyman is offline
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Default Case forming update...

Just back from a range trip yesterday, where I was able to FINALLY get this all together after a 7 month wait for my new CZ527 American in 17 Hornet!

I'll split the report into two parts... an update on the 17 Hornet case forming info and a report on the performance of the CZ527 at the range.

So, firstly... case forming.

Here's an updated image showing the PRIVI (sold as Highland in Australia) case forming process:



I was able to scrounge several different types of 22 Hornet cases, to continue my investigation into the best alternative brass to the problematic Hornady factory brass. These included Winchester, Remington, Sako and PRIVI... all were neck annealed after reforming but before fireforming.

Winchester cases had poor results when reforming to 17 Hornet... despite annealing several necks split, and all were quite 'pot-bellied' from a smaller than SAAMI spec case head diameter leading to excessive expansion just above the web.
Remington cases were better, with no neck splits but some noticeable expansion above the web, but significantly less than Winchester.
Sako cases were very good, a small amount of expansion.
PRIVI cases were excellent, with barely discernible web expansion on fireforming. Once FLS the cases showed a very even dull sheen all round where the die had reworked the brass evenly.



I was also able to source 50 Hornady unprimed new cases (Lot #4130708), and was dismayed to find at least 30% had severely obstructed flash holes, which had to be drilled out and deburred. Out of a batch of 25, three also had primer recesses that were about .010" too shallow. All had the 'cupped' case head surface and most had correspondingly 'cupped' primer pocket faces with ragged edges along the radius into the primer cup.
NOT good for such expensive brass...



I mainly used the 20gr VMax (with 15 rounds of 20gr Berger FBHP) for fire forming and general load testing this time... once I have a batch of fireformed cases I will also test the 20gr Nosler Varmageddon.



Run out of the reformed PRIVI brass loaded with a 20gr VMax averaged around .009", after fireforming and FLS then reloaded with the same bullet run out averaged a very consistent .001". These reloads promise to be very accurate...

I have ordered some RWS Hornet cases to create some 'match spec' 17 Hornet brass... these cases are pretty much the reference standard with very consistent internal volumes. Will report back on this in due course...

So in summary...
I recommend the use of PRIVI 22 Hornet cases for your 17 Hornet case forming until Hornady sorts out their long-running quality control issues with the 17 Hornet cases. Keep loads away from maximum.
It's cheap, surprisingly good quality brass that matches the Hornady case head diameter and reforms perfectly!

Last edited by Tilleyman; 01-27-2014 at 09:24 AM. Reason: Summary revised after case sectioning discoveries...
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  #42  
Old 01-15-2014, 09:34 AM
Tilleyman Tilleyman is offline
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Default Case sectioning... some interesting discoveries!

Normally I like to be very 'data driven' when it comes to my load development, but the scarcity of info about the Hornady 17 Hornet made me assume (that dangerous word) that the internal structure of the PRIVI brass just had to be more solid if the case heads were not expanding as much as Winchester or Remington.

So I decided to section the cases I used in the previous post about 17 Hornet case forming from 22 Hornet parent brass...
Winchester
Remington
PRIVI
Sako
RWS
Hornady

The results were rather interesting

PRIVI brass actually has by far the lightest case head structure of all the cases sectioned... normally there is a generous radius from the flash hole to the case walls to allow stresses to flow smoothly. Standard engineering practice to not create a stress riser.

Sako cases had a strangely distorted lump around the flash hole, but then pinched down to quite a weak point in the head... therefore not recommended for the higher pressures encountered in the 17 Hornet.

RWS cases had thick sidewalls, a generous radius at the web and a substantial head thickness at the primer cup... very high quality brass indeed.

Both Remington and Winchester cases have this radius, but interestingly the new Hornady brass also had almost sharp corners like the PRIVI... on a new case designed for 50,000 psi. Would of course allow maximum internal case volume and corresponding powder loads, but to me a strange design decision given Hornady had a 'blank sheet of paper' for this cartridge.

I would say the reason both PRIVI and Hornady cases do not display the 'pot-bellied' excessive expansion of cases formed from Winchester and Remington is that the original case head diameter of both is larger at .2945" and therefore well supported by the chamber walls.

I marked 10 PRIVI and Hornady cases, and measured them at the same spot on the head (just in front of the extractor groove) both before and after firing and found no appreciable difference using a Mitutoyo Digimatic vernier caliper.

Granted I really should have been using a digital blade micrometer with +/- .0001" accuracy but the vernier should at least have picked up a head expansion trend if there was one.

Primer pockets on the PRIVI were fine after firing, no loose primers encountered.
RWS Brass had very small diameter flash holes, a decapping pin would just pass through vs PRIVI and Hornady.


Last edited by Tilleyman; 02-16-2014 at 08:01 PM. Reason: Re-photographed with primers removed, Sako and RWS added
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  #43  
Old 01-15-2014, 10:31 AM
XA-Coupe XA-Coupe is offline
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Excellent posts. I just got my 527 Varmint last week.

Very interested to see both the Privi and the Hornady cases visually appear to be thicker than the Winchester and Remington cases.

I have some Winchester cases that I was considering using .. I think I will hunt down some Privi or just wait until I get hold of some more hornady stuff.
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  #44  
Old 01-15-2014, 11:00 AM
Dean2 Dean2 is offline
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Tilleyman

Very good post and good picture. You are IMO correct that the web has something to do with case head expansion as well as expansion just ahead of the rim but the wall thickness is also a large contributing factor to a cases ability to handle pressure. Most military brass is heavier and thicker for exactly this reason. It reduces load volume but stands up to pressure excursions caused by poor headspace, lousy chamber fit etc.

I think we are seeing the same thing here. I have used the Privi brass for years to load 22 Hornet. It is one of my favourites. It holds the least powder of Rem, Win and Privi, but it lasts literally forever. I have never lost a Privi case and I don't anneal. I have cases with over 20 firings on them and that isn't supposed to be possible in a hornet. (Mind you to be fair I have some Winchester cases with over 15 firings on them). Privi is thicker and slightly larger in head and web size so it fits the chambers well without pot bellying.
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  #45  
Old 01-15-2014, 04:00 PM
mulepasture mulepasture is offline
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Very good post and the sectioned cases are very instructive..Privi design meets the challenges the physics present.
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  #46  
Old 01-16-2014, 02:58 AM
johno johno is offline
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A really good post mate, very imformative.

When do we see some range work? No doubt your getting the 40C plus tempreture also, so maybe the weekend

Johno
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  #47  
Old 01-16-2014, 10:07 AM
Tilleyman Tilleyman is offline
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Thanks guys, glad you found it interesting.

I've started forming RWS brass and will update with this info in due course...

And Johno... yeah was 44C here, too hot for any range trips!

Luckily I just finished writing up last week's range trip... see separate thread
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  #48  
Old 01-17-2014, 08:57 AM
Tilleyman Tilleyman is offline
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Default RWS brass reforming...

Just played about with reforming a few RWS Hornet cases to 17 Hornet...

As you would expect at A$1.70 each, the quality is superb... each one individually presented like tiny jewels in a display case.



Each case shows the tell tale blue neck annealing colours which extend down about 8mm and make the initial necking to .20 cal a piece of cake.

The flash holes were much smaller than any of the other cases, a decapping pin would only just pass through. RWS produces their own Small Rifle primers (#4033) which apparently have very tightly controlled brisance. Perhaps this plus the smaller diameter flash hole 'chokes' the intensity of the ignition similar to a Small Pistol primer but able to withstand much higher pressures.

Quality of the flash holes and primer pockets could not be faulted, everything neatly finished off and bevelled on the inside edge.



According to the RWS website:
Random samples are taken from each lot before production progresses.
These samples are assembled/filled to complete cartridges and subjected to extreme excess strains:
• at 10% excess pressure in especially prepared test barrels
with partly inadmissible head spaces of 0.2 mm and 0.4 mm.
These head spaces are to simulate worn weapons, which
exist on the market.
• At 30% excess pressure in test barrels produced to CIP specifications.


SAAMI maximum operating pressure for the 22 Hornet is 43,000 CUP, for the 17 Hornet is 50,000 psi/MAP... but it seems there is a degree of additional strength already built into the RWS Hornet brass.



The cases reformed very easily, but I noticed the brass is very yellow in colour and annealing colours displayed very brightly. It was also quite tough and 'stringy' when trimming to length vs the PRIVI which cut like butter.



There is really no additional fiddly prep work to do on these cases... just take them out of the box, neck to .20 cal, pass through the 17 Hornet FLS die, trim, neck anneal and you are ready to load.

If only they were a bit more affordable I'd happily use RWS instead of spending hours of extra prep on A$0.90 Hornady brass... only to end up with variable quality and questionable reliability concerning leakage at the primer pockets.

Last edited by Tilleyman; 02-16-2014 at 07:19 AM. Reason: RWS Hornet case image updated
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  #49  
Old 01-17-2014, 02:13 PM
hemiallen hemiallen is offline
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RWS looks like a good, albeit expensive option. Have you measured the diameter at the base where the bulge usually is? Hoping it is closer to the new 17HH brass is, ie closer to the chamber size of these guns. I believe the 17HH is 0.2950, while my WW is 0.292 to 0.293

Allen
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  #50  
Old 01-17-2014, 06:05 PM
Tilleyman Tilleyman is offline
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Allen
Yes, sorry it was the first thing I checked!
10 cases picked at random from 100 (all batch no 255967) measured a very consistent .2945" same median diameter as PRVI and Hornady.

My overall recommendation is that RWS is the best brass for the 17 Hornet given the very high quality, robust case walls, consistent primer pockets/flash holes and substantial head thickness. When combined with all the over pressure/excessive headspace 'torture tests' their brass is subjected to as part of internal Quality Control, RWS is pretty impressive!
The Mercedes Benz of Hornet brass, but you really do 'get what you pay for'

Hornady a distant second place until they can sort out the quality issues, but the case appears to be robust and designed to handle the full 50,000 psi SAAMI case pressure. Primer pocket issues notwithstanding...

PRVI
brass is good quality, cheap brass with the right case head diameter to prevent the 'pot bellying' evident on the smaller head diameter of Winchester and Remington. After sectioning the cases it's evident the head construction is a little lighter than RWS or Hornady but the wall thickness is robust.
I would recommend that PRVI 17 Hornet brass not be loaded right up to the raw edge of maximum, and it should give good service.

I do not recommend Winchester, Remington or Sako Hornet cases be used to reform to 17 Hornet due to smaller than SAAMI spec head diameter or the first two brands and the relatively weak inner head structure of the last brand.

As for me, I'm trying to find another 100 RWS cases at less eye-watering prices!
Saubier group buy opportunity?

Last edited by Tilleyman; 06-28-2014 at 08:06 AM. Reason: Corrected content and grammar...
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