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Old 03-04-2019, 09:43 AM
strud strud is offline
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Join Date: May 2018
Location: Central Tablelands NSW
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Default 17HH AR2207 QL discrepancy

Hi All,

Can't remember if I've posted here before, maybe regarding he 17HH case fiasco... I'm from Australia in the central tablelands and own a Sako 22-250 Hunter, Vanguard in 270WSM and now a nice little 17HH.

I have been reading all the 17HH posts on here for about a year now, after buying myself a CZ527 varmint in 17HH.

Up until recently I was using the Hornady 20gn Vmax factory ammo and then began working up some reloads using the fired cases.

I am using quickload to get a starting point and help me get to an accuracy node sooner than later, which has worked well for me in the past for the 22-250 and 270WSM I have.

The 20gn Vmax with 2205 has come in on the money with quickload, and I'm able to get to 3650 fps with 10.7gn on neck sized cases (14.7gn water capacity) 43.75mm COL and quite reasonable pressure levels.

The 25gn Vmax is another story.
I am using ar2207 with this bullet since ar2205 seems too fast for this.

The problem I'm having is that when compared with all my other simulations in QL, the velocity I'm getting on the chronograph is at least 200fps lower than QL predicts. No tweaking of the burnrate factor is getting me close without silly changes. I have used a number of 25gn 17cal bullets in the sims but all results come up about the same.
The prediction is for 3450fps with 11.6gn of 2207, 45.0mm COL, 14.7gn case capacity and about 41000psi.
Shooting this today gave me 3233, 3213 and 3241fps with chrony at 3m.

Other loads were also shot in the same session, with sensible numbers coming from the chrony.

Something worth mentioning is that my fired cases have about 0.6gn more capacity than new or FL sized cases. Not sure if this is excessive, but maybe my chamber is a little on the large size.

Thoughts or suggestions?
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CZ527 in 17HH
Weatherby Vanguard 270WSM
Sako L579 22-250
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  #2  
Old 03-04-2019, 03:31 PM
moorepower moorepower is offline
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Join Date: Mar 2011
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Looking at the Hodgdon data, using a compressed load of 11.1 grains they are getting 3187fps at 42,500psi with H 4198, which I think is the same powder. Can you get a CFE BLK from ADI? The ADI 2207/quickload estimate in the .17HH case looks to be off.
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  #3  
Old 03-04-2019, 06:53 PM
strud strud is offline
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Join Date: May 2018
Location: Central Tablelands NSW
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Thanks Moorepower

If I use 4198 in QL all else the same, the result is quite different. Pressure up to 43300 and vel down to 3300.

Data for 4198 looks quite different to that of ar2207 in QL, which is odd if these are meant t be the same powder.... will need to get to the bottom of that.

Regarding CFE blk, I have not tried to source this locally, will have a look about.
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CZ527 in 17HH
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Sako L579 22-250
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