Author Topic: 30-06 and H-4350, pressure sign?  (Read 779 times)

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Offline Buckfever

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30-06 and H-4350, pressure sign?
« on: July 15, 2008, 03:13:15 PM »
I have worked up the following load.  30-06, 180grn.Hornady Interbond, H-4350 56.6 grn.
I worked this load up slowly from 53grn. with the Max. in the books as 59.0 grn.  The load is very accurate and shoots .75 at 100 yards.  My only concern is that the primers appear to be slightly compressed.  I use Federal   #210.  I have de-primed and reloaded and have not seen any change to the size of the primer pocket.  There is no sign of a tight bolt, everything works fine.  Am I looking for something that does not exist?  Can you really tell anything from a slightly compressed primer?    Buckfever

Offline deltecs

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Re: 30-06 and H-4350, pressure sign?
« Reply #1 on: July 15, 2008, 03:34:28 PM »
My 30-06 with 165 gr and H4350 at 58 gr shows what appears to be flattened primers, just noticable.  This is also the case with every factory load tried in this rifle.  The factory loaded primers appear identical with those shot with my hand loads.  So, I don't think it is necessarily a pressure sign.  The expansion of the brass with the friction against the chamber is what actually holds the case from excessive thrust on the bolt face.  However, just before the brass can expand to seal against the chamber walls, a loose chamber permits the case to edge back against the bolt face and this may be causing the flattened primers slightly.  Severly flattened primers are obvious signs of pressure, but do not make the mistake of thinking one is not over acceptable pressure limits, when not.  Another possibility is having the chamber contaminated with too much lube, like gun oil.  The chamber should be dry and totally clean, when a tight swab is twisted inside it.  Cases may not have all the lube removed from sizing.  This allows the case to slip or not grab the chamber walls like designed.  Hope this helps.  I've done all the above and haven't had any decrease in the slightly flattened primers, either with factory or hand loads.  Another way to check for high pressure in the case is to take a paper clip and bend on end at 90* just enough to fit down the neck.  Insert it into the case all the way to the bottom and slowly drag the bent end along the case wall.  This will indicate if any excessive case stretching occurs, as a hollow will form beyond the base about a 1/16" from the extractor groove.  Any differences in case wall thickness at this point are signs of excessive pressure. 
Greg lost his battle with cancer last week on April 2nd 2009. RIP Greg. We miss you.

Greg
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Offline Lone Star

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Re: 30-06 and H-4350, pressure sign?
« Reply #2 on: July 15, 2008, 04:29:06 PM »
Quote
...Another way to check for high pressure in the case is to take a paper clip and bend on end at 90* just enough to fit down the neck.  Insert it into the case all the way to the bottom and slowly drag the bent end along the case wall.  This will indicate if any excessive case stretching occurs, as a hollow will form beyond the base about a 1/16" from the extractor groove.  Any differences in case wall thickness at this point are signs of excessive pressure.

Sorry, this is incorrect.  A thin spot in the case wall is an indication of excess headspace, not excess pressure.  Even low-pressure loads can exhibit an incipient head separation, the .35 Remington is a common prime example as chambers are often cut deep along with cases that are too short head-to-shoulder.  Primer appearance is also a poor indication of safe pressures, see the Speer manual for an explanation with photos.


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Offline beemanbeme

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Re: 30-06 and H-4350, pressure sign?
« Reply #3 on: July 16, 2008, 06:35:31 AM »
I don't know what book you're using nor what kind of 30-06 you've got but if you're only getting slightly flattened primers w/o any engraving on the case head and easy extraction, I'd say you're probably good to go.  Let the case longevity tell you more about it.  If you can't get several reloadings from each case before you start splitting necks or your primer pockets loosen, then you're running kinda hot. 
You didn't say what velocity you were running so I assume you don't have a Chrony. None of the books I have show 59 grains as a max for H4350. My Hodgdon book shows a max of 56 grains but it is several years old. IMO fudging .6 grs over (according to my books) isn't gonna end up with smoking shards of steel embedded in your brains but it will be harder on your brass. And too, I dislike motoring my rifles at the top end.
If it were my rifle, I think I'd back down to about 55.5 (or thereabouts) and see if my accuracy was still there and start saving my pennies to get one of those hundred dollar chronies that would help you answer this question.  You see, I daresay you will lose little or no meaningful velocity between 55.5 and 56.5grs of H4350.  :D

Offline stimpylu32

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Re: 30-06 and H-4350, pressure sign?
« Reply #4 on: July 16, 2008, 07:50:37 AM »
Buckfever

The Hodgdons web site lists a starting load at 52g and a max of 57.5g , relise this load is for the Sierra 180g BTSP not the Hornady 180g Interbond , that being said you are well in the ( book ) safe range with your powder charge .

As for the primer that you explained , that would lead me to think more of a very slight headspace issue as a cause not a over pressure problem .

stimpy
Deceased June 17, 2015


:D If i can,t stop it with 6 it can,t be stopped