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Increase in load pressure


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#31 Mr_Logic

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Posted 16 November 2009 - 10:08 pm

Ok so to do that I literally take a fired case, fill it with water, weigh that and that's what you're after?

#32 dicehorn

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Posted 16 November 2009 - 10:15 pm

Faced with the problems you are experiencing Mr L and noting you are getting a new batch of cases, I would seriously consider putting you hand in your pocket and getting a decent neck sizing die (RCBS or Redding) The problem with always using your full length die is that you are putting unneccessary pressure on your case each time when in reality once the case has been fire formed you really only need to reshape the neck which in turn means that your cases will last longer.

I am in the process of changing my R93 barrel for a new one and with the new barrel I shall be buying new cases acknowledging that even though the new barrel is still an R93, there will still be a chamber difference.

Bear in mind that case shoulders will also move forward especially in slack chambers - have you measured your shoulder datum length and compared it to a new case - you may be surprised how far it has crept forward and that going into a tight chamber........could be the reason

#33 Mr_Logic

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Posted 16 November 2009 - 10:44 pm

Excuse the relative newbie here, what's a shoulder datum when it's at home?!

#34 dicehorn

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Posted 16 November 2009 - 11:23 pm

Excuse the relative newbie here, what's a shoulder datum when it's at home?!


When its at home (yours preferably) :whistling: it's the length from the headstamp to the point where the shoulder starts to bend in towards the neck - to be accurate with this measurement you really need a shoulder gauge

http://www.midwayuk....leItemID=479704

Works on the same principles as a bullet comparator

#35 HUnter_zero

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Posted 17 November 2009 - 06:34 am

Ok so to do that I literally take a fired case, fill it with water, weigh that and that's what you're after?


Yes but keep in mind this is not really a fault finding exercise, more a theoretical exploration in to what happens with different powder weights. With the internal case capacity it means QL can calculate almost specific pressure traces which means the final data of chamber pressure and muzzle velocity is more accurate. I've had all sorts of problems reloading for my mates Howa .308, very tight chamber, very small throat etc. My standard .308 ammo will not even chamber in his rifle! He likes Winny silver tips, the fire formed cases come out with neck tension.

John

#36 Mr_Logic

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Posted 17 November 2009 - 06:11 pm

OK, when I get a mo I will do that and let you know.

#37 Mr_Logic

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Posted 19 November 2009 - 11:52 pm

Well new brass seems to have worked, 44gr of AA4350 (am saving H414 for heavier bullets) and the 80gr SBT and no pressure signs. Good group, too.

Now in Winchester brass.


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