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Old October 11, 2018, 07:05 AM   #26
Picher
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As to the claim that the last shot fired out of a magazine is a flyer, consider that cartridges in the magazine provide upward pressure on the forward part of the bolt, contributing to alignment with the bore. Changes in bolt position can cause variations in firing pin impacts with relation to the cartridge rim, hence affecting accuracy.

Examine the relative firing pin impacts of the last shot verses other shots. If there's a difference, consider modifying the firing pin, especially to impact a bit below the roll of the rim, regardless of the last shot fired. Since there's no priming compound at that point, the firing pin strikes will be deeper and more uniform if the top of the firing pin strike is just below that fold.

I learned that trick when accurizing 10-22s and modified my CZ firing pin, as described, and it made a difference in accuracy.
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Old October 15, 2018, 06:54 AM   #27
Mobuck
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I opened another full carton (2010 production)of Hornady 17 grain V-max yesterday and from the first box had 1 hangfire and numerous split neck/shoulder cases. I also discovered two different colors of the plastic tips which produced different POI within the same box. Six of the 10 boxes in the sealed carton pack contained the varied color tips.
Lack of accuracy and POI shift was so serious that I just stopped shooting the 17 until I dig out some different ammo.
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Old October 16, 2018, 08:43 AM   #28
Picher
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Mobuck: Did the unfired ammo have split neck/shoulder or fired cases?

My neighbor has a Savage .17 HMR that splits almost all cases. I suggested she return it to the dealer and it be sent to the factory for a new barrel with a verified chamber/headspace.
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Old October 16, 2018, 08:02 PM   #29
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Splits only after firing. Happens in all three rifles we have (77/17, RAR 17, and CZ Scout switch barrel). Doesn't happen with fresh CCI or Winchester ammo.
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